Clarification please on connection-limit

GlueGuy · Wed Apr 25, 2007 5:11 pm

We have LAN2 on our MT set up for guest access. We want to limit the total number of connections for all the clients on LAN2. It's not clear to me whether this rule limits "per client" or globally on the LAN2 interface:

;;; Drop invalid connections
chain=forward in-interface=LAN2 connection-state=invalid action=drop
;;; Allow established connections
chain=forward in-interface=LAN2 connection-state=established action=accept
;;; Allow only 40 connections
chain=forward in-interface=LAN2 protocol=tcp connection-limit=40,24 connection-state=new action=reject

Can someone let me know if this will do what we want; specifically to limit total connections on LAN2 to 40?

sroa · Thu Apr 26, 2007 8:22 pm

change connection-state=new with tcp-flags=syn and move all the rule before the one that accepts valid connections.

GlueGuy · Fri Apr 27, 2007 8:43 am

Not sure what you mean there.

Are you saying to make it like this?:

;;; Drop invalid connections
chain=forward in-interface=LAN2 connection-state=invalid action=drop
;;; Allow only 40 connections
chain=forward in-interface=LAN2 protocol=tcp tcp-flags=syn connection-limit=40,24 action=reject reject-with=tcp-reset
;;; Allow established connections
chain=forward in-interface=LAN2 connection-state=established action=accept

Why put the reject before allowing established connections? Would it not work essentially the same way if after that rule? Or did I misunderstand what you were saying?

sroa · Fri Apr 27, 2007 5:19 pm

If you put the rule to Allow established connections before, all the packets or connections that match (good connections) will exit the filter section and will not continue with the next rule that limits to 40.

You could try changing to 3 or 4 connections instead of 40 and then see the counters in Winbox to see if it limit to the number of connections that you want.

GlueGuy · Fri Apr 27, 2007 6:07 pm

I thought the rule:

;;; Allow established connections
chain=forward in-interface=LAN2 connection-state=established action=accept

would only pass connections that are already "established".

so... new connections (ones that are being established (e.g. new connections), would not match this rule?

And following along with that same thought, we would want to also allow "related" connections prior to the reject rule?

Clarification please on connection-limit

Clarification please on connection-limit

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