MikroTik Fasttrack with IPsec

Fasttrack is a new feature introduced in RouterOS v6.29 that allows you to forward packages in a way that they are not handled by the Linux Kernel which greatly improves the throughput of your router as well as lowering the CPU load.

Fasttrack allows all packages that have the state Established or Related to bypass the Kernel and be directly forwarded to the target. So, once a connection is marked as established or related, it won’t go through any firewalling or processing and will directly forwarded to the target. Of course – a connection gains the state of established or related once it went through the firewall so it will still be secure.

But there’s a known issue that Fasttrack will not work with IPsec connections, it will result in a rather wonky experience or very unstable IPsec connection. So if you have IPsec connections in your MikroTik but want to take the advantages of Fasttrack, here’s the resolution for you!

Firstly, we want to mark all IPsec connections:

/ip firewall mangle add action=mark-connection chain=forward comment="mark ipsec connections" ipsec-policy=out,ipsec new-connection-mark=ipsec
/ip firewall mangle add action=mark-connection chain=forward comment="mark ipsec connections" ipsec-policy=in,ipsec new-connection-mark=ipsec

Secondly, we want to create a new Fasttrack rule but excluding all IPsec connections that we have marked with the two mangle rules above:

/ip firewall filter add chain=forward action=fasttrack-connection connection-state=established,related connection-mark=!ipsec
/ip firewall filter add chain=forward action=accept connection-state=established,related

Don’t forget to delete your old Fasttrack rule if any.

I’ve been using this rule in my live IPsec site-to-site tunnel and the result is just simply amazing!

Let me know if you have any question or comment by posting down below. Cheers!

MikroTik Site-to-Site IPsec Tunnel

Easy Guide on how to setup MikroTik Site-to-Site IPsec Tunnel

If one of MikroTik’s WAN IP address is dynamic, set up that router as the initiator (i.e. dial-out)

If you are working from WAN, don’t forget to enable Safe Mode.

Let’s go to Winbox -> IP -> IPsec -> Proposals, and this is the IPsec proposal I usually use:

It compatible with DrayTek Routers as well, see the picture below:

IPsec Policy

Let’s go to IP -> IPsec -> on Policies, click on + and on the Action tab, fill in the following:

<tick> Tunnel if it’s not ticked.

SA Src. Address: <WAN IP Address of this MikroTik> (this can be blanked, if this MikroTik has dynamic WAN IP address)
SA Dst. Address: <WAN IP Address of the other MikroTik>
Proposal: Select the proposal we created before (i.e. proposal-younameit)

Then click on General tab, and fill with the following:

Src. Address: <Internal LAN IP of this MikroTik
Dst. Address: <Internal LAN IP of the other side>
<untick> Template if it’s ticked.

IPsec Peers

Now let’s go to peers tab to setup the other phase:

If the initiator has dynamic WAN IP, set Generate Policy = port strict on the responder side. Port strict will generate policies and use ports from peer’s proposal, which should match peer’s policy. This is also useful when remote peer’s IP address is unknown at the configuration time, basically allowing the peer to establish SA for non-existing policies.

Setup the same (just reverse the SRC/DST) on the other side of tunnel, if your tunnel works, you will see on IPsec -> Installed SAs.

Last but not least, we need to setup a Firewall NAT rule that allows LAN IP in our MikroTik goes through the tunnel:

On the Action tab, set Action: accept.

Click Apply then OK and put this rule above the masquerade srcnat rule.

I hope this guide works for you, but if you have any question or comment please don’t hesitate to write down below, and I would happy to respond.