NAT to two different servers on the same port via hostname with Mikrotik RB2011

Question

I have a Mikrotik RB2011 router, running RouterOS which connects to the internet via a static IP. In my lan I have two different servers, one that is on IP 192.168.89.11 and another on 192.168.89.12

My DNS (on cloudflare) resolves both myfirstserver.com and mysecondserver.com to my router's static IP.

Now, what I want to do is to somehow separate the traffic so all traffic for myfirstserver.com goes to 192.168.89.11 and traffic for mysecondserver.com goes to 192.168.89.12 (and both on port 80. I know I could just change ports but if these are servers publicly available, no user would set a different port than 80)

What I have tried so far, is to somehow mark the packets through mangle and then use that mark on NAT to do the proper dst-nat forward.

I try marking packets through either content or Layer 7 protocol regex (they work properly if the action is log. I can see them being logged correctly).

The thing is that after I mark them, it seems that NAT just ignores them and forwards the connection to the server that accepts the non-marked packets.

I think I have mixed up the order of filtering and the chains somehow.

Would someone be able to provide some pointers/assistance on how to accomplish this?

Thanks!

EDIT: My question is very specific, about marking packets in RouterOS on a Mikrotik router and checking the mark in NAT. it is not about whether i need a reverse proxy or whatever. Thanks

EDIT 2: @Cha0s asked my /ip firewall export so here it is:

/ip firewall layer7-protocol
add name=haf1a regexp=haf1a

/ip firewall address-list
add address=192.168.89.0/24 list=local
add address=192.168.88.0/24 list=local
add address=www.xxx.yyy.zzz list=local
add address=192.168.87.0/24 list=local

/ip firewall filter
add chain=input comment="default configuration" protocol=icmp
add chain=input comment="default configuration" connection-state=established
add chain=input comment="default configuration" connection-state=related
add action=drop chain=virus comment="Drop 80 DoS attack" src-address-list=spammer
add action=add-src-to-address-list address-list=spammer address-list-timeout=1d chain=input connection-limit=10,32 dst-address-list=!local dst-port=53 protocol=udp
add action=drop chain=input dst-port=53 protocol=udp src-address-list=!local
add action=add-src-to-address-list address-list=spammer address-list-timeout=1d chain=input connection-limit=30,32 protocol=tcp
/ip firewall mangle
add action=change-mss chain=forward new-mss=1422 out-interface=all-ppp protocol=tcp tcp-flags=syn tcp-mss=1423-65535

/ip firewall nat
add action=masquerade chain=srcnat comment="default configuration" out-interface=ether1-gateway
add action=masquerade chain=srcnat out-interface=pppoe-out1
add action=dst-nat chain=dstnat comment="No HAF mark" dst-address=www.xxx.yyy.zzz dst-port=80 packet-mark=!haf1 port="" protocol=tcp src-port="" to-addresses=192.168.89.41 to-ports=80
add action=dst-nat chain=dstnat comment="HAF mark" dst-address=www.xxx.yyy.zzz dst-port=80 packet-mark=haf1 port="" protocol=tcp src-port="" to-addresses=192.168.89.31 to-ports=80

where www.xxx.yyy.zzz is my external ip (static) and 192.168.89.31 and 192.168.89.41 my two servers inside my local network

My goal is to redirect any connections with haf1a in them (eg haf1a.lala.com) to the relevant server (192.168.89.31)

Solution

Thanks for the export.

It turns out that either this configuration is not supported by MikroTik or there is a bug.

According to the Packet Flow Diagram, if I understand it correctly, dst-nat should be able to detect the packet/connection marks since mangle prerouting is before dst-nat. But after some tests of my own I got stuck the same as you did.

While mangle/filter can match the marked packets (or even without marking, but by directly using the L7 filter on the rules) on nat it simply does not match any packets.

There are also various relevant threads on the MikroTik forums, which none seem to have found a solution.

http://forum.mikrotik.com/viewtopic.php?f=2&t=83129

http://forum.mikrotik.com/viewtopic.php?f=2&t=73856

http://forum.mikrotik.com/viewtopic.php?f=13&t=62152

One guy mentions a solution by using the WebProxy of MikroTik, which I personally wouldn't use since it will change the source IP address to the IP of MikroTik and thus the webservers will log all requests with the same IP instead of the real visitors' IPs.

I can think of two other solutions but are not that straightforward.

Solution 1: If you are using version 5.x of MikroTik there is an ISO image that will patch MikroTik and add a minimal debian distro on top (or bellow) it. Which then you can use to install HAproxy or any other reverse proxy you like to accomplish what you need properly (HAproxy or any other reverse proxy is the correct way to do this as others have already mentioned)

Solution 2: Another approach is to create a metarouter (if you run MikroTik on a routerboard, you have enough free RAM and you don't use nstreme) and load an openwrt image on it. On which you can then install a reverse proxy of your liking to accomplish the task.

Most likely not a solution: Of course you could also send a support ticket to MikroTik to confirm or (most likely) deny that there is a bug on NAT with L7 packet marking. But I wouldn't expect much from their support. Most of the time will not help you at all. Their default strategy is that everyone is stupid and the problem is always on the users' configuration and not on MikroTik itself...

It would be nice to be able to handle this task on the router itself. It's suitable for constrained environments where putting yet another machine to do the reverse proxy is not an option. Though I wouldn't use this method (even if it worked) on a production environment. Layer 7 filter is quite slow and heavy for the router.

Update: I just saw that you are using RB2011, so the ISO/debian solution won't work for you (it's only for x86). If you are not using nstreme (I guess not) then your only bet is by using a metarouter with openwrt to do the reverse proxy stuff for you.

Comments

[FooBee]

Setup a HTTP reverse proxy on the router or forward the traffic to one that one delivers the traffic to the real servers (this could even be one of the real servers).

[pataroulis]

thank you but this is not what I need as I want all ports to be seamlessly NATed to the respective servers. Not just http traffic

[FooBee]

It's not going to work then. HTTP has a method to differentiate traffic meant for different servers, but many protocols have not and there is no way to trick around that.

[pataroulis]

I edited the question to make it Mikrotik-specific. I just need an answer on how I can mark packets when they enter the router so I can be able to check them on NAT

[Cha0s]

Please post the results of /ip firewall export here so we can understand your setup. Your described method (L7 regex + NAT rules) sounds right. But if the NAT rules don't match the packets properly there probably is an error in your configuration.

[Cha0s]

Also you don't need to mark any packets. You simply create the L7 regex rules and then the NAT rules that will dst-nat the matched packets to the configured IPs/Ports.

[pataroulis]

I edited the question to make it Mikrotik-specific. I just need an answer on how I can mark packets when they enter the router so I can be able to check them on NAT

[pataroulis]

Oh my! thanks for going to such depth for an answer. Really appreciate you didn't go the "Can't work, now mark my answer correct" approach. Will try one step at a time with the metarouter. Didn't even know I can do such a thing. Thanks again!

[Cha0s]

Glad I could help :)