Mikrotik ipsec error no suitable proposal found

Fri Mar 29, 2019 11:31 am

Two days ago I configured 4 x GRE / IPSec tunnels on my CCR running 6.42.12. I use this exact same configuration elsewhere successfully on a CCR running 6.42.6. All 4 tunnels were up and stable and BGP neighbours connected and exchanging routes as expected.

Yesterday morning I noticed that the one tunnel is down. Log indicate ph2 cannot establish and the log is flooded with “ipsec failed to pre-process ph2 packet”. The policy for the tunnel was marked in red (I recall this was usually an indication that the policy was invalid).

Anyways I went through the process of clearing all SAs, enabling and disabling the peer, the policy, the associated addresses etc. multiple times without the ph2 re-establishing. Resetting the tunnel from the far end also had no effect. I deleted the peer and policy and recreated with the exact same result. I double checked all configs making 100% sure there were no overlapping subnets but I could not find any issue. None of the other 3 tunnels showed the same behavior.

At some stage I left the policy disabled for quite a while (guessing > 30 mins). After enabling it, to my surprise, the ph2 established. I was just wondering if this is perhaps know behavior that was introduced somewhere between 6.42.6 and 6.42.12? Or any other thoughts?

It still seems stable ever since.

Re: IPSec failed to pre-process ph2 packet

Fri Mar 29, 2019 2:35 pm

I’ve been seeing this (apparent data corruption in IPSec packets when changing configuration) on my home ac2.

It’s fixed in 6.43 or 6.44 — can’t remember exactly — but it was mentioned in change logs.

Re: IPSec failed to pre-process ph2 packet

Tue Apr 02, 2019 10:19 am

Re: IPSec failed to pre-process ph2 packet

Mon Apr 08, 2019 2:00 pm

Does anyone here perhaps have any specific information on why the ph2 policies would out of the blue go into an invalid state? This happens randomly and I cannot reproduce on demand so trying to roll forward version by version is going take forever.

Like I mentioned before, disabling the policy for an extended amount of time and then enabling it seems to resolve the problem. The problem is not on the device at the far end as I have other routers terminating tunnels with the same configuration on the same device that never show this behavior.

Re: IPSec failed to pre-process ph2 packet

Sat Apr 13, 2019 7:48 pm

As removing and re-creating the peers and policies didn’t help while «letting everything cool down for a while» did, I’d suspect some connection tracking issue somewhere, possibly in the network between the two devices, where an existing connection had to time out and disappear from the connection tracking tables in order to allow the peers to establish communication again. However, respond new phase 1 (Identity Protection) followed by no suitable proposal found suggest something more complex, like multiple local side peers being configured, with different Phase 1 proposals (aka peer profiles), and the wrong one to be hit by the incoming packet.

If you want a more detailed response, follow the hint in my automatic signature, configurations from both ends are necessary.

The phase 2 issue existed only for IKEv2 and it only happened once in many renegotiations while both ends showed everything to be just fine except that the data did not get through because the encryption keys differed between the ends. So I think your case is completely unrelated to that issue (and I don’t remember in which version it has been fixed a year ago or so although it was me who has reported it).

Re: IPSec failed to pre-process ph2 packet

Tue Apr 16, 2019 9:23 am

Thank you for your response.

I have another Mikrotik router in another location that terminates GRE/IPSec tunnels on the exact same device on the far end (VyOS running StrongSwan) and I have never seen this behavior. As a test I downgraded the ROS version of the «problematic» router to 6.42.6. 3 days in the issue occurred again — one policy marked as invalid. Without any intervention, 6 hours later it recovered. I think you are correct that it might be due to connection tracking somewhere. The strange thing is that the far end indicates ph1 and ph2 up. Resetting the tunnels from the far side has not effect. The only thing that I can thing of that is different is that the connection over which the policies change to invalid states, is via a PPPoE internet connection. In other locations where this configurations successfully used, the internet connections are direct fibre connections. What are your thoughts on this? One thing I have not tried yet is actually disabling and re-enabling the PPPoE client session to see if that makes a difference (previously I just tried to remove the relevant UDP 500 and ESP connections from connection tracking). Btw, connection tracking on my Mikrotik routers are configured as «auto».

One other thing that you have mentioned are the proposals. Even though all the IPSec tunnels on the router in question are configured to use the same proposal (add enc-algorithms=aes-128-cbc lifetime=1h name=vpn-core) there is another policy (the default one) used for inbound L2TP over IPSec connections from remote users (find default=yes ] enc-algorithms=aes-256-cbc pfs-group=modp2048) . If this policy is somehow used, then I can understand that there will be an issue but I cannot see how that would happen?

Again, you views would be greatly appreciated.

Re: IPSec failed to pre-process ph2 packet

Wed Apr 17, 2019 10:33 am

When I checked this morning, one policy marked as invalid once more.

Enabling and disabling the PPPOE had not effect.

Changing the crypto to the same settings as the ones used in the default policy had not effect.

The device on the far side indicated both ph1 and ph2 up. Bizarrely even though the policy on the Mikrotik is marked as invalid and clearly indicated as not established, the GRE interface is in a running state and the BGP neighbor connected. So this seems to me that even tough the policy is marked as invalid in the UI as well as the terminal, somewhere, somehow a valid policy is still installed. When I enable and disable the peer, the ph1 reestablished immediately but ph2 does not reestablish and obviously the BGP neighbor now looses comms as the GRE is not in a running state. No matter what I do, I cannot force the policy into a valid state again — after x hours, it just magically recovers. Diagnostic logs indicate: ipsec,debug no policy found for id:11473.

I quite urgently need to get this resolved — again, any assistance would be greatly appreciated.

Below the invalid policy with traffic flowing correctly as if the tunnel is working 100% (prior to resetting the peer):

Re: IPSec failed to pre-process ph2 packet

Wed Apr 17, 2019 11:44 am

What makes my brain slide a bit is that you use the IP address attached to the GRE interface also as a local address to send the GRE transport packets from. Could you, just for testing, create an /interface bridge without any member ports and attach to it the IP address which is used as local-address of /interface gre (and thus the src-address of the /ip ipsec policy ) and use a different address for the GRE interface itself (I don’t mind which one of the two will remain the current one and for which purpose you’ll use a new one)? I have no idea how this would be done at VyOS side but it should be possible as well.

Also, I’m nor sure why you’ve assigned a /32 address to one GRE tunnel and a /30 address to another one.

As you seem not to mind publishing your public IP addresses, can you post the log which says «no policy found»? There should be more information in the log than just this.

Please show me also the output of /ip ipsec policy print and /ip ipsec installed-sa print when it runs but the policy is marked as inactive. The encryption and authentication keys shown in the installed-sa printouts are temporary ones so no need to edit them out, it is enough to wait up to 30 minutes before posting them.

Re: IPSec failed to pre-process ph2 packet

Wed Apr 17, 2019 12:53 pm

Once more thank you for the reply. Below the output of the peer and sa status. I have also attached the log, obfuscated the IPs as per the config provided and marked non-relevant IPs as x.x.x.x.

Re: IPSec failed to pre-process ph2 packet

Wed Apr 17, 2019 1:39 pm

First of all, all occurrences of ipsec policy not found in the log you’ve sent are preceded by a message ipsec searching for policy for selector: 169.254.200.49 ip-proto:47 169.254.200.50 ip-proto:47 which doesn’t match the parameters of the /ip ipsec policy you’ve shown in the quotation from your config in post #6 ( dst-address=169.254.200.66/32 src-address=169.254.200.65/32 ). Post #9 shows the policy matching the log, not the configuration. Is this because you’ve split the IPs as I’ve asked you before?

Second, showing just parts of the configuration and status outputs breaks the purpose, my intention was to check the existing policies (including dynamically created ones) for shadowing each other, which you’ve ruined by showing just the single policy and SA. So please post the complete printout as requested — as text, not as screenshot. You can always direct the output of a print to a file by adding file=some-name , download the file and edit it before posting to hide the IPs, but such editing has to preserve consistency — the same IP address must be substituted by the same replacement string in the whole file, and the traffic selector addresses of the policies ( src-address and dst-address ) must remain completely unchanged to show the eventual shadowing of policies by preceding ones.

Re: IPSec failed to pre-process ph2 packet

Wed Apr 17, 2019 4:35 pm

Hi, on your first question — no, as you can see in post #7, (dst-address=169.254.200.66/32 src-address=169.254.200.65/32) is another policy used by another tunnel. This tunnel also shows the same sporadic behaviour. The config for it was supplied in this thread as use the problematic tunnel as an example when the policies go into an invalid state — I cannot predict when this happens and I supplied the information that was available to me at the time.

I have subsequently moved the source address of the GRE tunnel to a bridge interface as per your suggestion.

My apologies that the configs were not supplied to your satisfaction. I have added it below as per your request. I have also substituted all the public addresses consistently.

Re: IPSec failed to pre-process ph2 packet

Wed Apr 17, 2019 6:36 pm

My personal opinion is that has nothing to do with configuration. None of your other policies can shadow the one mysteriously going inactive, even if we’d admit that the order of the policies wouldn’t matter. It normally does but when you add a new policy this used to fail in older ROS releases, e.g. on the 6.43.8 where I’ve just tested it.

So it is either a bug or, if the other Routerboard/CHR /x86 on which you’ve never seen the issue to happen is the same model like the problematic one, there can be a hardware (RAM) issue on the problematic one.

So you may try the following steps and hope that one of them works around the bug (the last one may «fix» rather than «workaround» it although none of the changelog items listed below is guaranteed to be related):

separate the addresses used to send for the GRE transport (to be matched by the IPsec policy) from the addresses attached to the GRE interface, at least on Mikrotik side, the way I’ve suggested above; doing so will allow you to remove the protocol=gre from the traffic selector of the /ip ipsec policy
set the sa-src-address of the policy to 0.0.0.0 . It may make things better (the policy won’t jump inactive) or worse (it won’t ever come up), the idea is just to force a different branch of the algorithm, not something precisely targeted to a known issue
set the level to unique instead of the current require — same motivation like above
upgrade to 6.43.12 (the last available one before 6.44 — to keep the structure of IPsec configuration you are used to)

The following items in the changelog may be related:

6.42.7: *) ipsec — improved invalid policy handling when a valid policy is uninstalled;
6.43:
- *) ike2 — fixed initiator first policy selection;
- *) ipsec — improved invalid policy handling when a valid policy is uninstalled;
- *) ipsec — improved reliability on generated policy addition when IKEv1 or IKEv2 used;

The «improved invalid policy handling when a valid policy is uninstalled» is mentioned also in 6.44 changelog, so it seems to be a complex issue.

Источник

IPsec

Internet Protocol Security (IPsec) is a set of protocols defined by the Internet Engineering Task Force (IETF) to secure packet exchange over unprotected IP/IPv6 networks such as the Internet.

IPsec protocol suite can be divided into the following groups:

Internet Key Exchange (IKE) protocols. Dynamically generates and distributes cryptographic keys for AH and ESP.
Authentication Header (AH) RFC 4302
Encapsulating Security Payload (ESP) RFC 4303

Internet Key Exchange Protocol (IKE)

The Internet Key Exchange (IKE) is a protocol that provides authenticated keying material for the Internet Security Association and Key Management Protocol (ISAKMP) framework. There are other key exchange schemes that work with ISAKMP, but IKE is the most widely used one. Together they provide means for authentication of hosts and automatic management of security associations (SA).

Most of the time IKE daemon is doing nothing. There are two possible situations when it is activated:

There is some traffic caught by a policy rule which needs to become encrypted or authenticated, but the policy doesn’t have any SAs. The policy notifies the IKE daemon about that, and the IKE daemon initiates a connection to a remote host. IKE daemon responds to remote connection. In both cases, peers establish a connection and execute 2 phases:

Phase 1 — The peers agree upon algorithms they will use in the following IKE messages and authenticate. The keying material used to derive keys for all SAs and to protect following ISAKMP exchanges between hosts is generated also. This phase should match the following settings:
- authentication method
- DH group
- encryption algorithm
- exchange mode
- hash algorithm
- NAT-T
- DPD and lifetime (optional)

Phase 2 — The peers establish one or more SAs that will be used by IPsec to encrypt data. All SAs established by the IKE daemon will have lifetime values (either limiting time, after which SA will become invalid, or the amount of data that can be encrypted by this SA, or both). This phase should match the following settings:
- IPsec protocol
- mode (tunnel or transport)
- authentication method
- PFS (DH) group
- lifetime

There are two lifetime values — soft and hard. When SA reaches its soft lifetime threshold, the IKE daemon receives a notice and starts another phase 2 exchange to replace this SA with a fresh one. If SA reaches a hard lifetime, it is discarded.

Phase 1 is not re-keyed if DPD is disabled when the lifetime expires, only phase 2 is re-keyed. To force phase 1 re-key, enable DPD.

PSK authentication was known to be vulnerable against Offline attacks in «aggressive» mode, however recent discoveries indicate that offline attack is possible also in the case of «main» and «ike2» exchange modes. A general recommendation is to avoid using the PSK authentication method.

IKE can optionally provide a Perfect Forward Secrecy (PFS), which is a property of key exchanges, that, in turn, means for IKE that compromising the long term phase 1 key will not allow to easily gain access to all IPsec data that is protected by SAs established through this phase 1. It means an additional keying material is generated for each phase 2.

The generation of keying material is computationally very expensive. Exempli Gratia, the use of the modp8192 group can take several seconds even on a very fast computer. It usually takes place once per phase 1 exchange, which happens only once between any host pair and then is kept for a long time. PFS adds this expensive operation also to each phase 2 exchange.

Diffie-Hellman Groups

Diffie-Hellman (DH) key exchange protocol allows two parties without any initial shared secret to create one securely. The following Modular Exponential (MODP) and Elliptic Curve (EC2N) Diffie-Hellman (also known as «Oakley») Groups are supported:

Diffie-Hellman Group	Name	Reference
Group 1	768 bits MODP group	RFC 2409
Group 2	1024 bits MODP group	RFC 2409
Group 3	EC2N group on GP(2^155)	RFC 2409
Group 4	EC2N group on GP(2^185)	RFC 2409
Group 5	1536 bits MODP group	RFC 3526
Group 14	2048 bits MODP group	RFC 3526
Group 15	3072 bits MODP group	RFC 3526
Group 16	4096 bits MODP group	RFC 3526
Group 17	6144 bits MODP group	RFC 3526
Group 18	8192 bits MODP group	RFC 3526
Group 19	256 bits random ECP group	RFC 5903
Group 20	384 bits random ECP group	RFC 5903
Group 21	521 bits random ECP group	RFC 5903

IKE Traffic

To avoid problems with IKE packets hit some SPD rule and require to encrypt it with not yet established SA (that this packet perhaps is trying to establish), locally originated packets with UDP source port 500 are not processed with SPD. The same way packets with UDP destination port 500 that are to be delivered locally are not processed in incoming policy checks.

Setup Procedure

To get IPsec to work with automatic keying using IKE-ISAKMP you will have to configure policy, peer, and proposal (optional) entries.

IPsec is very sensitive to time changes. If both ends of the IPsec tunnel are not synchronizing time equally(for example, different NTP servers not updating time with the same timestamp), tunnels will break and will have to be established again.

EAP Authentication methods

PAP
CHAP
MS-CHAP
MS-CHAPv2
EAP-MSCHAPv2
EAP-GTC
EAP-MD5
EAP-TLS

EAP-TLS on Windows is called «Smart Card or other certificates».

Authentication Header (AH)

AH is a protocol that provides authentication of either all or part of the contents of a datagram through the addition of a header that is calculated based on the values in the datagram. What parts of the datagram are used for the calculation, and the placement of the header depends on whether tunnel or transport mode is used.

The presence of the AH header allows to verify the integrity of the message but doesn’t encrypt it. Thus, AH provides authentication but not privacy. Another protocol (ESP) is considered superior, it provides data privacy and also its own authentication method.

RouterOS supports the following authentication algorithms for AH:

Transport mode

In transport mode, the AH header is inserted after the IP header. IP data and header is used to calculate authentication value. IP fields that might change during transit, like TTL and hop count, are set to zero values before authentication.

Tunnel mode

In tunnel mode, the original IP packet is encapsulated within a new IP packet. All of the original IP packets are authenticated.

Encapsulating Security Payload (ESP)

Encapsulating Security Payload (ESP) uses shared key encryption to provide data privacy. ESP also supports its own authentication scheme like that used in AH.

ESP packages its fields in a very different way than AH. Instead of having just a header, it divides its fields into three components:

ESP Header — Comes before the encrypted data and its placement depends on whether ESP is used in transport mode or tunnel mode.
ESP Trailer — This section is placed after the encrypted data. It contains padding that is used to align the encrypted data.
ESP Authentication Data — This field contains an Integrity Check Value (ICV), computed in a manner similar to how the AH protocol works, for when ESP’s optional authentication feature is used.

Transport mode

In transport mode, the ESP header is inserted after the original IP header. ESP trailer and authentication value are added to the end of the packet. In this mode only the IP payload is encrypted and authenticated, the IP header is not secured.

Tunnel mode

In tunnel mode, an original IP packet is encapsulated within a new IP packet thus securing IP payload and IP header.

Encryption algorithms

RouterOS ESP supports various encryption and authentication algorithms.

MD5
SHA1
SHA2 (256-bit, 512-bit)

AES — 128-bit, 192-bit, and 256-bit key AES-CBC, AES-CTR, and AES-GCM algorithms;
Blowfish — added since v4.5
Twofish — added since v4.5
Camellia — 128-bit, 192-bit, and 256-bit key Camellia encryption algorithm added since v4.5
DES — 56-bit DES-CBC encryption algorithm;
3DES — 168-bit DES encryption algorithm;

Hardware acceleration

Hardware acceleration allows doing a faster encryption process by using a built-in encryption engine inside the CPU.

List of devices with hardware acceleration is available here

Outer Auth	Inner Auth
EAP-GTC
EAP-MD5
EAP-MSCHAPv2
EAP-PEAPv0

CPU	DES and 3DES				AES-CBC				AES-CTR				AES-GCM
CPU	MD5	SHA1	SHA256	SHA512	MD5	SHA1	SHA256	SHA512	MD5	SHA1	SHA256	SHA512	MD5	SHA1	SHA256	SHA512
88F7040	no	yes	yes	yes	no	yes	yes	yes	no	yes	yes	yes	no	no	no	no
AL21400	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes
AL32400	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes
AL52400	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes
AL73400	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes
IPQ-4018 / IPQ-4019	no	yes	yes	no	no	yes*	yes*	no	no	yes*	yes*	no	no	no	no	no
IPQ-8064	no	yes	yes	no	no	yes*	yes*	no	no	yes*	yes*	no	no	no	no	no
MT7621A	yes****	yes****	yes****	no	yes	yes	yes	no	no	no	no	no	no	no	no	no
P1023NSN5CFB	no	no	no	no	yes**	yes**	yes**	yes**	no	no	no	no	no	no	no	no
P202ASSE2KFB	yes	yes	yes	no	yes	yes	yes	yes	no	no	no	no	no	no	no	no
PPC460GT	no	no	no	no	yes***	yes***	yes***	yes***	yes***	yes***	yes***	yes***	no	no	no	no
TLR4 (TILE)	yes	yes	yes	no	yes	yes	yes	no	yes	yes	yes	no	no	no	no	no
x86 (AES-NI)	no	no	no	no	yes***	yes***	yes***	yes***	yes***	yes***	yes***	yes***	yes***	yes***	yes***	yes***

* supported only 128 bit and 256 bit key sizes

** only manufactured since 2016, serial numbers that begin with number 5 and 7

*** AES-CBC and AES-CTR only encryption is accelerated, hashing done in software

**** DES is not supported, only 3DES and AES-CBC

IPsec throughput results of various encryption and hash algorithm combinations are published on the MikroTik products page.

Policies

The policy table is used to determine whether security settings should be applied to a packet.

Properties

Property	Description
action (discard \| encrypt \| none; Default: encrypt)	Specifies what to do with the packet matched by the policy. none — pass the packet unchanged. discard — drop the packet. encrypt — apply transformations specified in this policy and it’s SA.
comment (string; Default: )	Short description of the policy.
disabled (yes \| no; Default: no)	Whether a policy is used to match packets.
dst-address (IP/IPv6 prefix; Default: 0.0.0.0/32)	Destination address to be matched in packets. Applicable when tunnel mode (tunnel=yes) or template (template=yes) is used.
dst-port (integer:0..65535 \| any; Default: any)	Destination port to be matched in packets. If set to any all ports will be matched.
group (string; Default: default)	Name of the policy group to which this template is assigned.
ipsec-protocols (ah \| esp; Default: esp)	Specifies what combination of Authentication Header and Encapsulating Security Payload protocols you want to apply to matched traffic.
level (require \| unique \| use; Default: require)	Specifies what to do if some of the SAs for this policy cannot be found: use — skip this transform, do not drop the packet, and do not acquire SA from IKE daemon; require — drop the packet and acquire SA; unique — drop the packet and acquire a unique SA that is only used with this particular policy. It is used in setups where multiple clients can sit behind one public IP address (clients behind NAT).
peer (string; Default: )	Name of the peer on which the policy applies.
proposal (string; Default: default)	Name of the proposal template that will be sent by IKE daemon to establish SAs for this policy.
protocol (all \| egp \| ggp\| icmp \| igmp \| . ; Default: all)	IP packet protocol to match.
src-address (ip/ipv6 prefix; Default: 0.0.0.0/32)	Source address to be matched in packets. Applicable when tunnel mode (tunnel=yes) or template (template=yes) is used.
src-port (any \| integer:0..65535; Default: any)	Source port to be matched in packets. If set to any all ports will be matched.
template (yes \| no; Default: no)	Creates a template and assigns it to a specified policy group.

Following parameters are used by template:

group — name of the policy group to which this template is assigned;
src-address, dst-address — Requested subnet must match in both directions(for example 0.0.0.0/0 to allow all);
protocol — protocol to match, if set to all, then any protocol is accepted;
proposal — SA parameters used for this template;
level — useful when unique is required in setups with multiple clients behind NAT.

tunnel (yes | no; Default: no) Specifies whether to use tunnel mode.

Read-only properties

Property	Description
active (yes \| no)	Whether this policy is currently in use.
default (yes \| no)	Whether this is a default system entry.
dynamic (yes \| no)	Whether this is a dynamically added or generated entry.
invalid (yes \| no)	Whether this policy is invalid — the possible cause is a duplicate policy with the same src-address and dst-address.
ph2-count (integer)	A number of active phase 2 sessions associated with the policy.
ph2-state (expired \| no-phase2 \| established)	Indication of the progress of key establishing.
sa-dst-address (ip/ipv6 address; Default: ::)	SA destination IP/IPv6 address (remote peer).
sa-src-address (ip/ipv6 address; Default: ::)	SA source IP/IPv6 address (local peer).

Policy order is important starting from v6.40. Now it works similarly to firewall filters where policies are executed from top to bottom (priority parameter is removed).

All packets are IPIP encapsulated in tunnel mode, and their new IP header’s src-address and dst-address are set to sa-src-address and sa-dst-address values of this policy. If you do not use tunnel mode (id est you use transport mode), then only packets whose source and destination addresses are the same as sa-src-address and sa-dst-address can be processed by this policy. Transport mode can only work with packets that originate at and are destined for IPsec peers (hosts that established security associations). To encrypt traffic between networks (or a network and a host) you have to use tunnel mode.

Statistics

This menu shows various IPsec statistics and errors.

Read-only properties

Property	Description
in-errors (integer)	All inbound errors that are not matched by other counters.
in-buffer-errors (integer)	No free buffer.
in-header-errors (integer)	Header error.
in-no-states (integer)	No state is found i.e. either inbound SPI, address, or IPsec protocol at SA is wrong.
in-state-protocol-errors (integer)	Transformation protocol-specific error, for example, SA key is wrong or hardware accelerator is unable to handle the number of packets.
in-state-mode-errors (integer)	Transformation mode-specific error.
in-state-sequence-errors (integer)	A sequence number is out of a window.
in-state-expired (integer)	The state is expired.
in-state-mismatches (integer)	The state has a mismatched option, for example, the UDP encapsulation type is mismatched.
in-state-invalid (integer)	The state is invalid.
in-template-mismatches (integer)	No matching template for states, e.g. inbound SAs are correct but the SP rule is wrong. A possible cause is a mismatched sa-source or sa-destination address.
in-no-policies (integer)	No policy is found for states, e.g. inbound SAs are correct but no SP is found.
in-policy-blocked (integer)	Policy discards.
in-policy-errors (integer)	Policy errors.
out-errors (integer)	All outbound errors that are not matched by other counters.
out-bundle-errors (integer)	Bundle generation error.
out-bundle-check-errors (integer)	Bundle check error.
out-no-states (integer)	No state is found.
out-state-protocol-errors (integer)	Transformation protocol specific error.
out-state-mode-errors (integer)	Transformation mode-specific error.
out-state-sequence-errors (integer)	Sequence errors, for example, sequence number overflow.
out-state-expired (integer)	The state is expired.
out-policy-blocked (integer)	Policy discards.
out-policy-dead (integer)	The policy is dead.
out-policy-errors (integer)	Policy error.

Proposals

Proposal information that will be sent by IKE daemons to establish SAs for certain policies.

Properties

Property	Description
auth-algorithms (md5\|null\|sha1\|sha256\|sha512; Default: sha1)	Allowed algorithms for authorization. SHA (Secure Hash Algorithm) is stronger but slower. MD5 uses a 128-bit key, sha1-160bit key.
comment (string; Default: )
disabled (yes \| no; Default: no)	Whether an item is disabled.
enc-algorithms (null\|des\|3des\|aes-128-cbc\|aes-128-cbc\|aes-128gcm\|aes-192-cbc\|aes-192-ctr\|aes-192-gcm\|aes-256-cbc\|aes-256-ctr\|aes-256-gcm\|blowfish\|camellia-128\|camellia-192\|camellia-256\|twofish; Default: aes-256-cbc,aes-192-cbc,aes-128-cbc)	Allowed algorithms and key lengths to use for SAs.
lifetime (time; Default: 30m)	How long to use SA before throwing it out.
name (string; Default: )
pfs-group (ec2n155 \| ec2n185 \| ecp256 \| ecp384 \| ecp521 \| modp768 \| modp1024 \| modp1536 \| modp2048 \| modp3072 \| modp4096 \| modp6144 \| modp8192 \| none; Default: modp1024)	The diffie-Helman group used for Perfect Forward Secrecy.

Read-only properties

Property	Description
default (yes \| no)	Whether this is a default system entry.

Groups

In this menu, it is possible to create additional policy groups used by policy templates.

Properties

Property	Description
name (string; Default: )
comment (string; Default: )

Peers

Peer configuration settings are used to establish connections between IKE daemons. This connection then will be used to negotiate keys and algorithms for SAs. Exchange mode is the only unique identifier between the peers, meaning that there can be multiple peer configurations with the same remote-address as long as a different exchange-mode is used.

Properties

Property	Description
address (IP/IPv6 Prefix; Default: 0.0.0.0/0)	If the remote peer’s address matches this prefix, then the peer configuration is used in authentication and establishment of Phase 1. If several peer’s addresses match several configuration entries, the most specific one (i.e. the one with the largest netmask) will be used.
comment (string; Default: )	Short description of the peer.
disabled (yes \| no; Default: no)	Whether peer is used to matching remote peer’s prefix.
exchange-mode (aggressive \| base \| main \| ike2; Default: main)	Different ISAKMP phase 1 exchange modes according to RFC 2408. the main mode relaxes rfc2409 section 5.4, to allow pre-shared-key authentication in the main mode. ike2 mode enables Ikev2 RFC 7296. Parameters that are ignored by IKEv2 proposal-check, compatibility-options, lifebytes, dpd-maximum-failures, nat-traversal.
local-address (IP/IPv6 Address; Default: )	Routers local address on which Phase 1 should be bounded to.
name (string; Default: )
passive (yes \| no; Default: no)	When a passive mode is enabled will wait for a remote peer to initiate an IKE connection. The enabled passive mode also indicates that the peer is xauth responder, and disabled passive mode — xauth initiator. When a passive mode is a disabled peer will try to establish not only phase1 but also phase2 automatically, if policies are configured or created during the phase1.
port (integer:0..65535; Default: 500)	Communication port used (when a router is an initiator) to connect to remote peer in cases if remote peer uses the non-default port.
profile (string; Default: default)	Name of the profile template that will be used during IKE negotiation.
send-initial-contact (yes \| no; Default: yes)	Specifies whether to send «initial contact» IKE packet or wait for remote side, this packet should trigger the removal of old peer SAs for current source address. Usually, in road warrior setups clients are initiators and this parameter should be set to no. Initial contact is not sent if modecfg or xauth is enabled for ikev1.

Read-only properties

Property	Description
dynamic (yes \| no)	Whether this is a dynamically added entry by a different service (e.g L2TP).
responder (yes \| no)	Whether this peer will act as a responder only (listen to incoming requests) and not initiate a connection.

Identities

Identities are configuration parameters that are specific to the remote peer. The main purpose of identity is to handle authentication and verify the peer’s integrity.

Properties

Property	Description
auth-method (digital-signature \| eap \| eap-radius \| pre-shared-key \| pre-shared-key-xauth \| rsa-key \| rsa-signature-hybrid; Default: pre-shared-key)	Authentication method: digital-signature — authenticate using a pair of RSA certificates; eap — IKEv2 EAP authentication for initiator (peer with a netmask of /32). Must be used together with eap-methods; eap-radius — IKEv2 EAP RADIUS passthrough authentication for the responder (RFC 3579). A server certificate in this case is required. If a server certificate is not specified then only clients supporting EAP-only (RFC 5998) will be able to connect. Note that the EAP method should be compatible with EAP-only; pre-shared-key — authenticate by a password (pre-shared secret) string shared between the peers (not recommended since an offline attack on the pre-shared key is possible); rsa-key — authenticate using an RSA key imported in keys menu. Only supported in IKEv1; pre-shared-key-xauth — authenticate by a password (pre-shared secret) string shared between the peers + XAuth username and password. Only supported in IKEv1; rsa-signature-hybrid — responder certificate authentication with initiator XAuth. Only supported in IKEv1.
certificate (string; Default: )	Name of a certificate listed in System/Certificates (signing packets; the certificate must have the private key). Applicable if digital signature authentication method (auth-method=digital-signature) or EAP (auth-method=eap) is used.
comment (string; Default: )	Short description of the identity.
disabled (yes \| no; Default: no)	Whether identity is used to match remote peers.
eap-methods (eap-mschapv2 \| eap-peap \| eap-tls \| eap-ttls; Default: eap-tls)	All EAP methods requires whole certificate chain including intermediate and root CA certificates to be present in System/Certificates menu. Also, the username and password (if required by the authentication server) must be specified. Multiple EAP methods may be specified and will be used in a specified order. Currently supported EAP methods: eap-mschapv2; eap-peap — also known as PEAPv0/EAP-MSCHAPv2; eap-tls — requires additional client certificate specified under certificate parameter; eap-ttls.
generate-policy (no \| port-override \| port-strict; Default: no)	Allow this peer to establish SA for non-existing policies. Such policies are created dynamically for the lifetime of SA. Automatic policies allows, for example, to create IPsec secured L2TP tunnels, or any other setup where remote peer’s IP address is not known at the configuration time. no — do not generate policies; port-override — generate policies and force policy to use any port (old behavior); port-strict — use ports from peer’s proposal, which should match peer’s policy.
key (string; Default: )	Name of the private key from keys menu. Applicable if RSA key authentication method (auth-method=rsa-key) is used.
match-by (remote-id \| certificate; Default: remote-id)	Defines the logic used for peer’s identity validation. remote-id — will verify the peer’s ID according to remote-id setting. certificate will verify the peer’s certificate with what is specified under remote-certificate setting.
mode-config (none \| request-only \| string; Default: none*)	Name of the configuration parameters from mode-config menu. When parameter is set mode-config is enabled.
my-id (auto \| address \| fqdn \| user-fqdn \| key-id; Default: auto)	On initiator, this controls what ID_i is sent to the responder. On responder, this controls what ID_r is sent to the initiator. In IKEv2, responder also expects this ID in received ID_r from initiator. auto — tries to use correct ID automatically: IP for pre-shared key, SAN (DN if not present) for certificate based connections; address — IP address is used as ID; dn — The binary Distinguished Encoding Rules (DER) encoding of an ASN.1 X.500 Distinguished Name; fqdn — fully qualified domain name; key-id — use the specified key ID for the identity; user fqdn — specifies a fully-qualified username string, for example, «user@domain.com».
notrack-chain (string; Default: )	Adds IP/Firewall/Raw rules matching IPsec policy to a specified chain. Use together with generate-policy.
password (string; Default: )	XAuth or EAP password. Applicable if pre-shared key with XAuth authentication method (auth-method=pre-shared-key-xauth) or EAP (auth-method=eap) is used.
peer (string; Default: )	Name of the peer on which the identity applies.
policy-template-group (none \| string; Default: default)	If generate-policy is enabled, traffic selectors are checked against templates from the same group. If none of the templates match, Phase 2 SA will not be established.
remote-certificate (string; Default: )	Name of a certificate (listed in System/Certificates) for authenticating the remote side (validating packets; no private key required). If a remote-certificate is not specified then the received certificate from a remote peer is used and checked against CA in the certificate menu. Proper CA must be imported in a certificate store. If remote-certificate and match-by=certificate is specified, only the specific client certificate will be matched. Applicable if digital signature authentication method (auth-method=digital-signature) is used.
remote-id (auto \| fqdn \| user-fqdn \| key-id \| ignore; Default: auto)	This parameter controls what ID value to expect from the remote peer. Note that all types except for ignoring will verify remote peer’s ID with a received certificate. In case when the peer sends the certificate name as its ID, it is checked against the certificate, else the ID is checked against Subject Alt. Name. auto — accept all ID’s; fqdn — fully qualified domain name. Only supported in IKEv2; user fqdn — a fully-qualified username string, for example, «user@domain.com». Only supported in IKEv2; key-id — specific key ID for the identity. Only supported in IKEv2; ignore — do not verify received ID with certificate (dangerous).
remote-key (string; Default: )	Name of the public key from keys menu. Applicable if RSA key authentication method (auth-method=rsa-key) is used.
secret (string; Default: )	Secret string. If it starts with ‘0x’, it is parsed as a hexadecimal value. Applicable if pre-shared key authentication method (auth-method=pre-shared-key and auth-method=pre-shared-key-xauth) is used.
username (string; Default: )	XAuth or EAP username. Applicable if pre-shared key with XAuth authentication method (auth-method=pre-shared-key-xauth) or EAP (auth-method=eap) is used.

Read only properties

Property	Description
dynamic (yes \| no)	Whether this is a dynamically added entry by a different service (e.g L2TP).

Profiles

Profiles define a set of parameters that will be used for IKE negotiation during Phase 1. These parameters may be common with other peer configurations.

Properties

Property	Description
dh-group (modp768 \| modp1024 \| ec2n155 \| ec2n185 \| modp1536 \| modp2048 \| modp3072 \| modp4096 \| modp6144 \| modp8192 \| ecp256 \| ecp384 \| ecp521; Default: modp1024,modp2048)	Diffie-Hellman group (cipher strength)
dpd-interval (time \| disable-dpd; Default: 2m)	Dead peer detection interval. If set to disable-dpd, dead peer detection will not be used.
dpd-maximum-failures (integer: 1..100; Default: 5)	Maximum count of failures until peer is considered to be dead. Applicable if DPD is enabled.
enc-algorithm (3des \| aes-128 \| aes-192 \| aes-256 \| blowfish \| camellia-128 \| camellia-192 \| camellia-256 \| des; Default: aes-128)	List of encryption algorithms that will be used by the peer.
hash-algorithm (md5 \| sha1 \| sha256 \| sha512; Default: sha1)	Hashing algorithm. SHA (Secure Hash Algorithm) is stronger, but slower. MD5 uses 128-bit key, sha1-160bit key.
lifebytes (Integer: 0..4294967295; Default: )	Phase 1 lifebytes is used only as administrative value which is added to proposal. Used in cases if remote peer requires specific lifebytes value to establish phase 1.
lifetime (time; Default: 1d)	Phase 1 lifetime: specifies how long the SA will be valid.
name (string; Default: )
nat-traversal (yes \| no; Default: yes)	Use Linux NAT-T mechanism to solve IPsec incompatibility with NAT routers between IPsec peers. This can only be used with ESP protocol (AH is not supported by design, as it signs the complete packet, including the IP header, which is changed by NAT, rendering AH signature invalid). The method encapsulates IPsec ESP traffic into UDP streams in order to overcome some minor issues that made ESP incompatible with NAT.
proposal-check (claim \| exact \| obey \| strict; Default: obey)	Phase 2 lifetime check logic: claim — take shortest of proposed and configured lifetimes and notify initiator about it exact — require lifetimes to be the same obey — accept whatever is sent by an initiator strict — if the proposed lifetime is longer than the default then reject the proposal otherwise accept a proposed lifetime

Active Peers

This menu provides various statistics about remote peers that currently have established phase 1 connection.

Read only properties

Property	Description
dynamic-address (ip/ipv6 address)	Dynamically assigned an IP address by mode config
last-seen (time)	Duration since the last message received by this peer.
local-address (ip/ipv6 address)	Local address on the router used by this peer.
natt-peer (yes \| no)	Whether NAT-T is used for this peer.
ph2-total (integer)	The total amount of active IPsec security associations.
remote-address (ip/ipv6 address)	The remote peer’s ip/ipv6 address.
responder (yes \| no)	Whether the connection is initiated by a remote peer.
rx-bytes (integer)	The total amount of bytes received from this peer.
rx-packets (integer)	The total amount of packets received from this peer.
side (initiator \| responder)	Shows which side initiated the Phase1 negotiation.
state (string)	State of phase 1 negotiation with the peer. For example, when phase1 and phase 2 are negotiated it will show state «established».
tx-bytes (integer)	The total amount of bytes transmitted to this peer.
tx-packets (integer)	The total amount of packets transmitted to this peer.
uptime (time)	How long peers are in an established state.

Commands

Property	Description
kill-connections ()	Manually disconnects all remote peers.

Mode configs

ISAKMP and IKEv2 configuration attributes are configured in this menu.

Properties

Property	Description
address (none \| string; Default: )	Single IP address for the initiator instead of specifying a whole address pool.
address-pool (none \| string; Default: )	Name of the address pool from which the responder will try to assign address if mode-config is enabled.
address-prefix-length (integer [1..32]; Default: )	Prefix length (netmask) of the assigned address from the pool.
comment (string; Default: )
name (string; Default: )
responder (yes \| no; Default: no)	Specifies whether the configuration will work as an initiator (client) or responder (server). The initiator will request for mode-config parameters from the responder.
split-include (list of IP prefix; Default: )	List of subnets in CIDR format, which to tunnel. Subnets will be sent to the peer using the CISCO UNITY extension, a remote peer will create specific dynamic policies.
src-address-list (address list; Default: )	Specifying an address list will generate dynamic source NAT rules. This parameter is only available with responder=no. A roadWarrior client with NAT
static-dns (list of IP; Default: )	Manually specified DNS server’s IP address to be sent to the client.
system-dns (yes \| no; Default: )	When this option is enabled DNS addresses will be taken from /ip dns .

Read-only properties

Property	Description
default (yes \| no)	Whether this is a default system entry.

Not all IKE implementations support multiple split networks provided by the split-include option.

If RouterOS client is initiator, it will always send CISCO UNITY extension, and RouterOS supports only split-include from this extension.

It is not possible to use system-dns and static-dns at the same time.

Installed SAs

This menu provides information about installed security associations including the keys.

Read-only properties

Property	Description
AH (yes \| no)	Whether AH protocol is used by this SA.
ESP (yes \| no)	Whether ESP protocol is used by this SA.
add-lifetime (time/time)	Added lifetime for the SA in format soft/hard: soft — time period after which IKE will try to establish new SA; hard — time period after which SA is deleted.
addtime (time)	Date and time when this SA was added.
auth-algorithm (md5 \| null \| sha1 \| . )	Currently used authentication algorithm.
auth-key (string)	Used authentication key.
current-bytes (64-bit integer)	A number of bytes seen by this SA.
dst-address (IP)	The destination address of this SA.
enc-algorithm (des \| 3des \| aes-cbc \| . )	Currently used encryption algorithm.
enc-key (string)	Used encryption key.
enc-key-size (number)	Used encryption key length.
expires-in (yes \| no)	Time left until rekeying.
hw-aead (yes \| no)	Whether this SA is hardware accelerated.
replay (integer)	Size of replay window in bytes.
spi (string)	Security Parameter Index identification tag
src-address (IP)	The source address of this SA.
state (string)	Shows the current state of the SA («mature», «dying» etc)

Commands

Property	Description
flush ()	Manually removes all installed security associations.

This menu lists all imported public and private keys, that can be used for peer authentication. Menu has several commands to work with keys.

Properties

Property	Description
name (string; Default: )

Read-only properties

Property	Description
key-size (1024 \| 2048 \| 4096)	Size of this key.
private-key (yes \| no)	Whether this is a private key.
rsa (yes \| no)	Whether this is an RSA key.

Commands

Property	Description
export-pub-key (file-name; key)	Export public key to file from one of existing private keys.
generate-key (key-size; name)	Generate a private key. Takes two parameters, name of the newly generated key and key size 1024,2048 and 4096.
import (file-name; name)	Import key from file.

Settings

Property	Description
accounting (yes \| no; Default: )	Whether to send RADIUS accounting requests to a RADIUS server. Applicable if EAP Radius (auth-method=eap-radius) or pre-shared key with XAuth authentication method (auth-method=pre-shared-key-xauth) is used.
interim-update (time; Default: )	The interval between each consecutive RADIUS accounting Interim update. Accounting must be enabled.
xauth-use-radius (yes \| no; Default: )	Whether to use Radius client for XAuth users or not.

Application Guides

RoadWarrior client with NAT

Consider setup as illustrated below. RouterOS acts as a RoadWarrior client connected to Office allowing access to its internal resources.

A tunnel is established, a local mode-config IP address is received and a set of dynamic policies are generated.

Currently, only packets with a source address of 192.168.77.254/32 will match the IPsec policies. For a local network to be able to reach remote subnets, it is necessary to change the source address of local hosts to the dynamically assigned mode config IP address. It is possible to generate source NAT rules dynamically. This can be done by creating a new address list that contains all local networks that the NAT rule should be applied. In our case, it is 192.168.88.0/24.

By specifying the address list under the mode-config initiator configuration, a set of source NAT rules will be dynamically generated.

When the IPsec tunnel is established, we can see the dynamically created source NAT rules for each network. Now every host in 192.168.88.0/24 is able to access Office’s internal resources.

Allow only IPsec encapsulated traffic

There are some scenarios where for security reasons you would like to drop access from/to specific networks if incoming/outgoing packets are not encrypted. For example, if we have L2TP/IPsec setup we would want to drop nonencrypted L2TP connection attempts.

There are several ways how to achieve this:

Using IPsec policy matcher in firewall;
Using generic IPsec policy with action set to drop and lower priority (can be used in Road Warrior setups where dynamic policies are generated);
By setting DSCP or priority in mangle and matching the same values in firewall after decapsulation.

IPsec policy matcher

Let’s set up an IPsec policy matcher to accept all packets that matched any of the IPsec policies and drop the rest:

IPsec policy matcher takes two parameters direction, policy . We used incoming direction and IPsec policy. IPsec policy option allows us to inspect packets after decapsulation, so for example, if we want to allow only GRE encapsulated packet from a specific source address and drop the rest we could set up the following rules:

For L2TP rule set would be:

Using generic IPsec policy

The trick of this method is to add a default policy with an action drop. Let’s assume we are running an L2TP/IPsec server on a public 1.1.1.1 address and we want to drop all nonencrypted L2TP:

Now router will drop any L2TP unencrypted incoming traffic, but after a successful L2TP/IPsec connection dynamic policy is created with higher priority than it is on default static rule, and packets matching that dynamic rule can be forwarded.

Policy order is important! For this to work, make sure the static drop policy is below the dynamic policies. Move it below the policy template if necessary.

Manually specifying local-address parameter under Peer configuration

Using different routing table

IPsec, as any other service in RouterOS, uses the main routing table regardless of what local-address parameter is used for Peer configuration. It is necessary to apply routing marks to both IKE and IPSec traffic.

Consider the following example. There are two default routes — one in the main routing table and another in the routing table «backup». It is necessary to use the backup link for the IPsec site to site tunnel.

IPsec peer and policy configurations are created using the backup link’s source address, as well as the NAT bypass rule for IPsec tunnel traffic.

Currently, we see «phase1 negotiation failed due to time up» errors in the log. It is because IPsec tries to reach the remote peer using the main routing table with an incorrect source address. It is necessary to mark UDP/500, UDP/4500, and ipsec-esp packets using Mangle:

Using the same routing table with multiple IP addresses

Consider the following example. There are multiple IP addresses from the same subnet on the public interface. Masquerade rule is configured on out-interface. It is necessary to use one of the IP addresses explicitly.

IPsec peer and policy configuration is created using one of the public IP addresses.

Currently, the phase 1 connection uses a different source address than we specified, and «phase1 negotiation failed due to time up» errors are shown in the logs. This is because masquerade is changing the source address of the connection to match the pref-src address of the connected route. The solution is to exclude connections from the public IP address from being masqueraded.

Application examples

Site to Site IPsec (IKEv1) tunnel

Consider setup as illustrated below. Two remote office routers are connected to the internet and office workstations are behind NAT. Each office has its own local subnet, 10.1.202.0/24 for Office1 and 10.1.101.0/24 for Office2. Both remote offices need secure tunnels to local networks behind routers.

Site 1 configuration

Start off by creating a new Phase 1 profile and Phase 2 proposal entries using stronger or weaker encryption parameters that suit your needs. It is advised to create separate entries for each menu so that they are unique for each peer in case it is necessary to adjust any of the settings in the future. These parameters must match between the sites or else the connection will not establish.

Continue by configuring a peer . Specify the address of the remote router. This address should be reachable through UDP/500 and UDP/4500 ports, so make sure appropriate actions are taken regarding the router’s firewall. Specify the name for this peer as well as the newly created profile .

The next step is to create an identity . For a basic pre-shared key secured tunnel, there is nothing much to set except for a strong secret and the peer to which this identity applies.

If security matters, consider using IKEv2 and a different auth-method .

Lastly, create a policy that controls the networks/hosts between whom traffic should be encrypted.

Site 2 configuration

Office 2 configuration is almost identical to Office 1 with proper IP address configuration. Start off by creating a new Phase 1 profile and Phase 2 proposal entries:

Next is the peer and identity:

When it is done, create a policy :

At this point, the tunnel should be established and two IPsec Security Associations should be created on both routers:

NAT and Fasttrack Bypass

At this point if you try to send traffic over the IPsec tunnel, it will not work, packets will be lost. This is because both routers have NAT rules (masquerade) that are changing source addresses before a packet is encrypted. A router is unable to encrypt the packet because the source address does not match the address specified in the policy configuration. For more information see the IPsec packet flow example.

To fix this we need to set up IP/Firewall/NAT bypass rule.

Office 1 router:

Office 2 router:

If you previously tried to establish an IP connection before the NAT bypass rule was added, you have to clear the connection table from the existing connection or restart both routers.

It is very important that the bypass rule is placed at the top of all other NAT rules.

Another issue is if you have IP/Fasttrack enabled, the packet bypasses IPsec policies. So we need to add accept rule before FastTrack.

However, this can add a significant load to the router’s CPU if there is a fair amount of tunnels and significant traffic on each tunnel.

The solution is to use IP/Firewall/Raw to bypass connection tracking, that way eliminating the need for filter rules listed above and reducing the load on CPU by approximately 30%.

Site to Site GRE tunnel over IPsec (IKEv2) using DNS

This example explains how it is possible to establish a secure and encrypted GRE tunnel between two RouterOS devices when one or both sites do not have a static IP address. Before making this configuration possible, it is necessary to have a DNS name assigned to one of the devices which will act as a responder (server). For simplicity, we will use RouterOS built-in DDNS service IP/Cloud .

Site 1 (server) configuration

This is the side that will listen to incoming connections and act as a responder. We will use mode config to provide an IP address for the second site, but first, create a loopback (blank) bridge and assign an IP address to it that will be used later for GRE tunnel establishment.

Continuing with the IPsec configuration, start off by creating a new Phase 1 profile and Phase 2 proposal entries using stronger or weaker encryption parameters that suit your needs. Note that this configuration example will listen to all incoming IKEv2 requests, meaning the profile configuration will be shared between all other configurations (e.g. RoadWarrior).

Next, create a new mode config entry with responder=yes . This will provide an IP configuration for the other site as well as the host (loopback address) for policy generation.

It is advised to create a new policy group to separate this configuration from any existing or future IPsec configuration.

Now it is time to set up a new policy template that will match the remote peers new dynamic address and the loopback address.

The next step is to create a peer configuration that will listen to all IKEv2 requests. If you already have such an entry, you can skip this step.

Lastly, set up an identity that will match our remote peer by pre-shared-key authentication with a specific secret .

The server side is now configured and listening to all IKEv2 requests. Please make sure the firewall is not blocking UDP/4500 port.

The last step is to create the GRE interface itself. This can also be done later when an IPsec connection is established from the client-side.

Configure IP address and route to remote network through GRE interface.

Site 2 (client) configuration

Similarly to server configuration, start off by creating a new Phase 1 profile and Phase 2 proposal configurations. Since this site will be the initiator, we can use a more specific profile configuration to control which exact encryption parameters are used, just make sure they overlap with what is configured on the server-side.

Next, create a new mode config entry with responder=no . This will make sure the peer requests IP and split-network configuration from the server.

It is also advised to create a new policy group to separate this configuration from any existing or future IPsec configuration.

Create a new policy template on the client-side as well.

Move on to peer configuration. Now we can specify the DNS name for the server under the address parameter. Obviously, you can use an IP address as well.

Lastly, create an identity for our newly created peers.

If everything was done properly, there should be a new dynamic policy present.

A secure tunnel is now established between both sites which will encrypt all traffic between 192.168.99.2 192.168.99.1 addresses. We can use these addresses to create a GRE tunnel.

Configure IP address and route to remote network through GRE interface.

Road Warrior setup using IKEv2 with RSA authentication

This example explains how to establish a secure IPsec connection between a device connected to the Internet (road warrior client) and a device running RouterOS acting as a server.

RouterOS server configuration

Before configuring IPsec, it is required to set up certificates. It is possible to use a separate Certificate Authority for certificate management, however in this example, self-signed certificates are generated in RouterOS System/Certificates menu. Some certificate requirements should be met to connect various devices to the server:

Common name should contain IP or DNS name of the server;
SAN (subject alternative name) should have IP or DNS of the server;
EKU (extended key usage) tls-server and tls-client are required.

Considering all requirements above, generate CA and server certificates:

Now that valid certificates are created on the router, add a new Phase 1 profile and Phase 2 proposal entries with pfs-group=none:

Mode config is used for address distribution from IP/Pools:

Since that the policy template must be adjusted to allow only specific network policies , it is advised to create a separate policy group and template.

Create a new IPsec peer entry that will listen to all incoming IKEv2 requests.

Identity configuration

The identity menu allows to match specific remote peers and assign different configurations for each one of them. First, create a default identity, that will accept all peers, but will verify the peer’s identity with its certificate.

If the peer’s ID (ID_i) is not matching with the certificate it sends, the identity lookup will fail. See remote-id in the identities section.

For example, we want to assign a different mode config for user «A», who uses certificate «rw-client1» to authenticate itself to the server. First of all, make sure a new mode config is created and ready to be applied for the specific user.

It is possible to apply this configuration for user «A» by using the match-by=certificate parameter and specifying his certificate with remote-certificate .

(Optional) Split tunnel configuration

Split tunneling is a method that allows road warrior clients to only access a specific secured network and at the same time send the rest of the traffic based on their internal routing table (as opposed to sending all traffic over the tunnel). To configure split tunneling, changes to mode config parameters are needed.

For example, we will allow our road warrior clients to only access the 10.5.8.0/24 network.

It is also possible to send a specific DNS server for the client to use. By default, system-dns=yes is used, which sends DNS servers that are configured on the router itself in IP/DNS . We can force the client to use a different DNS server by using the static-dns parameter.

While it is possible to adjust the IPsec policy template to only allow road warrior clients to generate policies to network configured by split-include parameter, this can cause compatibility issues with different vendor implementations (see known limitations ). Instead of adjusting the policy template, allow access to a secured network in IP/Firewall/Filter and drop everything else.

Split networking is not a security measure. The client (initiator) can still request a different Phase 2 traffic selector.

Generating client certificates

To generate a new certificate for the client and sign it with a previously created CA.

PKCS12 format is accepted by most client implementations, so when exporting the certificate, make sure PKCS12 is specified.

A file named cert_export_rw-client1.p12 is now located in the routers System/File section. This file should be securely transported to the client’s device.

Typically PKCS12 bundle contains also a CA certificate, but some vendors may not install this CA, so a self-signed CA certificate must be exported separately using PEM format.

A file named cert_export_ca.crt is now located in the routers System/File section. This file should also be securely transported to the client’s device.

PEM is another certificate format for use in client software that does not support PKCS12. The principle is pretty much the same.

Three files are now located in the routers Files section: cert_export_ca.crt , cert_export_rw-client1.crt and cert_export_rw-client1.key which should be securely transported to the client device.

Known limitations

Here is a list of known limitations by popular client software IKEv2 implementations.

Windows will always ignore networks received by split-include and request policy with destination 0.0.0.0/0 (TSr). When IPsec-SA is generated, Windows requests DHCP option 249 to which RouterOS will respond with configured split-include networks automatically.

Both Apple macOS and iOS will only accept the first split-include network.

Both Apple macOS and iOS will use the DNS servers from system-dns and static-dns parameters only when 0.0.0.0/0 split-include is used.

While some implementations can make use of different PFS group for phase 2, it is advised to use pfs-group=none under proposals to avoid any compatibility issues.

RouterOS client configuration

Import a PKCS12 format certificate in RouterOS.

There should now be the self-signed CA certificate and the client certificate in the Certificate menu. Find out the name of the client certificate.

cert_export_RouterOS_client.p12_0 is the client certificate.

It is advised to create a separate Phase 1 profile and Phase 2 proposal configurations to not interfere with any existing IPsec configuration.

While it is possible to use the default policy template for policy generation, it is better to create a new policy group and template to separate this configuration from any other IPsec configuration.

Create a new mode config entry with responder=no that will request configuration parameters from the server.

Lastly, create peer and identity configurations.

Verify that the connection is successfully established.

Enabling dynamic source NAT rule generation

If we look at the generated dynamic policies, we see that only traffic with a specific (received by mode config) source address will be sent through the tunnel. But a router in most cases will need to route a specific device or network through the tunnel. In such case, we can use source NAT to change the source address of packets to match the mode config address. Since the mode config address is dynamic, it is impossible to create a static source NAT rule. In RouterOS, it is possible to generate dynamic source NAT rules for mode config clients.

For example, we have a local network 192.168.88.0/24 behind the router and we want all traffic from this network to be sent over the tunnel. First of all, we have to make a new IP/Firewall/Address list which consists of our local network

When it is done, we can assign the newly created IP/Firewall/Address list to the mode config configuration.

Verify correct source NAT rule is dynamically generated when the tunnel is established.

Make sure the dynamic mode config address is not a part of a local network.

Windows client configuration

Open PKCS12 format certificate file on the Windows computer. Install the certificate by following the instructions. Make sure you select the Local Machine store location. You can now proceed to Network and Internet settings -> VPN and add a new configuration. Fill in the Connection name, Server name, or address parameters. Select IKEv2 under VPN type. When it is done, it is necessary to select «Use machine certificates». This can be done in Network and Sharing Center by clicking the Properties menu for the VPN connection. The setting is located under the Security tab.

Currently, Windows 10 is compatible with the following Phase 1 ( profiles ) and Phase 2 ( proposals ) proposal sets:

Phase 1
Hash Algorithm	Encryption Algorithm	DH Group
SHA1	3DES	modp1024
SHA256	3DES	modp1024
SHA1	AES-128-CBC	modp1024
SHA256	AES-128-CBC	modp1024
SHA1	AES-192-CBC	modp1024
SHA256	AES-192-CBC	modp1024
SHA1	AES-256-CBC	modp1024
SHA256	AES-256-CBC	modp1024
SHA1	AES-128-GCM	modp1024
SHA256	AES-128-GCM	modp1024
SHA1	AES-256-GCM	modp1024
SHA256	AES-256-GCM	modp1024

Phase 2
Hash Algorithm	Encryption Algorithm	PFS Group
SHA1	AES-256-CBC	none
SHA1	AES-128-CBC	none
SHA1	3DES	none
SHA1	DES	none
SHA1	none	none

macOS client configuration

Open the PKCS12 format certificate file on the macOS computer and install the certificate in the «System» keychain. It is necessary to mark the CA certificate as trusted manually since it is self-signed. Locate the certificate macOS Keychain Access app under the System tab and mark it as Always Trust.

You can now proceed to System Preferences -> Network and add a new configuration by clicking the + button. Select Interface: VPN, VPN Type: IKEv2 and name your connection. Remote ID must be set equal to common-name or subjAltName of server’s certificate. Local ID can be left blank. Under Authentication Settings select None and choose the client certificate. You can now test the connectivity.

Currently, macOS is compatible with the following Phase 1 ( profiles) and Phase 2 ( proposals) proposal sets:

Phase 1
Hash Algorithm	Encryption Algorithm	DH Group
SHA256	AES-256-CBC	modp2048
SHA256	AES-256-CBC	ecp256
SHA256	AES-256-CBC	modp1536
SHA1	AES-128-CBC	modp1024
SHA1	3DES	modp1024

Phase 2
Hash Algorithm	Encryption Algorithm	PFS Group
SHA256	AES-256-CBC	none
SHA1	AES-128-CBC	none
SHA1	3DES	none

iOS client configuration

Typically PKCS12 bundle contains also a CA certificate, but iOS does not install this CA, so a self-signed CA certificate must be installed separately using PEM format. Open these files on the iOS device and install both certificates by following the instructions. It is necessary to mark the self-signed CA certificate as trusted on the iOS device. This can be done in Settings -> General -> About -> Certificate Trust Settings menu. When it is done, check whether both certificates are marked as «verified» under the Settings -> General -> Profiles menu.

You can now proceed to Settings -> General -> VPN menu and add a new configuration. Remote ID must be set equal to common-name or subjAltName of server’s certificate. Local ID can be left blank.

Currently, iOS is compatible with the following Phase 1 ( profiles) and Phase 2 ( proposals) proposal sets:

Phase 1
Hash Algorithm	Encryption Algorithm	DH Group
SHA256	AES-256-CBC	modp2048
SHA256	AES-256-CBC	ecp256
SHA256	AES-256-CBC	modp1536
SHA1	AES-128-CBC	modp1024
SHA1	3DES	modp1024

Phase 2
Hash Algorithm	Encryption Algorithm	PFS Group
SHA256	AES-256-CBC	none
SHA1	AES-128-CBC	none
SHA1	3DES	none

If you are connected to the VPN over WiFi, the iOS device can go into sleep mode and disconnect from the network.

Android (strongSwan) client configuration

Currently, there is no IKEv2 native support in Android, however, it is possible to use strongSwan from Google Play Store which brings IKEv2 to Android. StrongSwan accepts PKCS12 format certificates, so before setting up the VPN connection in strongSwan, make sure you download the PKCS12 bundle to your Android device. When it is done, create a new VPN profile in strongSwan, type in the server IP, and choose «IKEv2 Certificate» as VPN Type. When selecting a User certificate, press Install and follow the certificate extract procedure by specifying the PKCS12 bundle. Save the profile and test the connection by pressing on the VPN profile.

It is possible to specify custom encryption settings in strongSwan by ticking the «Show advanced settings» checkbox. Currently, strongSwan by default is compatible with the following Phase 1 ( profiles) and Phase 2 ( proposals) proposal sets:

Phase 1
Hash Algorithm	Encryption Algorithm	DH Group
SHA*	AES-*-CBC	modp2048
SHA*	AES-*-CBC	ecp256
SHA*	AES-*-CBC	ecp384
SHA*	AES-*-CBC	ecp521
SHA*	AES-*-CBC	modp3072
SHA*	AES-*-CBC	modp4096
SHA*	AES-*-CBC	modp6144
SHA*	AES-*-CBC	modp8192
SHA*	AES-*-GCM	modp2048
SHA*	AES-*-GCM	ecp256
SHA*	AES-*-GCM	ecp384
SHA*	AES-*-GCM	ecp521
SHA*	AES-*-GCM	modp3072
SHA*	AES-*-GCM	modp4096
SHA*	AES-*-GCM	modp6144
SHA*	AES-*-GCM	modp8192

Phase 2
Hash Algorithm	Encryption Algorithm	PFS Group
none	AES-256-GCM	none
none	AES-128-GCM	none
SHA256	AES-256-CBC	none
SHA512	AES-256-CBC	none
SHA1	AES-256-CBC	none
SHA256	AES-192-CBC	none
SHA512	AES-192-CBC	none
SHA1	AES-192-CBC	none
SHA256	AES-128-CBC	none
SHA512	AES-128-CBC	none
SHA1	AES-128-CBC	none

Linux (strongSwan) client configuration

Download the PKCS12 certificate bundle and move it to /etc/ipsec.d/private directory.

Add exported passphrase for the private key to /etc/ipsec.secrets file where «strongSwan_client.p12» is the file name and «1234567890» is the passphrase.

Add a new connection to /etc/ipsec.conf file

You can now restart (or start) the ipsec daemon and initialize the connection

Road Warrior setup using IKEv2 with EAP-MSCHAPv2 authentication handled by User Manager (RouterOS v7)

This example explains how to establish a secure IPsec connection between a device connected to the Internet (road warrior client) and a device running RouterOS acting as an IKEv2 server and User Manager. It is possible to run User Manager on a separate device in network, however in this example both User Manager and IKEv2 server will be configured on the same device (Office).