Port triggering HOWTO

RouterOS Forwarding Protocols
1

Please can someone help with port triggering?

I need to forward certain port to one of the clients who requested it.
The port is always the same but the IP address of the client is not always the same.

Thanks

2

why not just give the client a IP address that does not change. Its possible to do with script, and pick ip from mac address, but why make so much mess?

3

Thanks for your reply, and of course I could give clients fixed addresses and set port forwarding to every client (naturally with different ports), but…

All I need (or think I need) is simple port triggering:

http://en.wikipedia.org/wiki/Port_triggering
Port triggering is a way to automate port forwarding in which outbound traffic on predetermined ports (‘triggering ports’) causes inbound traffic to specific incoming ports to be dynamically forwarded to the initiating host, while the outbound ports are in use. This allows computers behind a NAT-enabled router on a local network to provide services that would normally require the computer to have a fixed address on the local network. Port triggering triggers can open an incoming port when a client on the local network makes an outgoing connection on a predetermined port or range of ports.

Since cheap 15$+ routers can do it, i believe that Mikrotik can.

Maybe there is something simpler than scripts? There must be something in NAT. Anyone?

4

its possible to try with upnp. I don’t know if it will work for you. but if you are going to manualy setup dst nat, you need to know the internal ip. Like I say. its POSSIBLE to do this by a script, but its a hassle.

I don’t know of anny 15$ nat box’s that is capable of automaticly update nat rules if a host change its ip.

5

I’m afraid that UPNP will just do normal port forwarding.

I don’t know of anny 15$ nat box’s that is capable of automaticly update nat rules if a host change its ip.

Here it is (sorry it’s almost 17$): http://www.ebay.com/ctg/TP-Link-TL-WR740N-150-Mbps-4-Port-10-100-Wireless-N-Router-/80048797
User manual page 51 and 52: http://www.tp-link.us/Resources/document/TL-WR740N_V4_UG.pdf

Is it possible that nobody didn’t need this before?

6

Hello again, i’ve done some torching my eth-gateway interface and noticed that what I want is happening by itself.
I see connections to that specific port I want to trigger, but port scanning reports that port closed (which is great).

Is it possible that this firewall rule is responsible:

chain=input connection-state=established action=accept

If so, than I’ve other problem, how to stop “rouge” clients to establishing unwanted connections?

BTW, Happy Easter to all.