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Any ability to rate limit connections?


I'm trying to determine whether Cisco has any equivalent (in any platform) to some of the existing firewall rules within our iptables infrastructure. Specifically these ones:

-A FORWARD -i eth0 -p tcp -m tcp --dport 3389 -m state --state NEW -m recent --set --name DEFAULT --rsource

-A FORWARD -i eth0 -p tcp -m tcp --dport 3389 -m state --state NEW -m recent --update --seconds 180 --hitcount 4 --name DEFAULT --rsource -j LOGDROP

-A FORWARD -p tcp -m state --state NEW -m tcp --dport 3389 -j ACCEPT


What this does, is allow port forwards on port 3389/rdp. However, if a single IP opens too many connections within a timeframe, it starts dropping new ones.

This is a critical requirements for certain security scenarios, such as preventing RDP brute forcing. A similar principle can be applied to 22/ssh.

I've had a look around, rate limiting searches generally land me on QoS based discussions. I've seen people ask similar questions and get referred to CBAC. Whilst I can see similarly worded functions there such as limiting "half open" connections, I don't see anything there that limits the actual number of connection attempts you can make.

Any assistance appreciated.

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Cisco Employee

Any ability to rate limit connections?

Both IOS and ASA firewall have embryonic and per-client max statments.

I would not call this feature rate limiting exactly though :-)

Now since both of those features are stateful they will rely on amount of (half?) open connections in their connection table rather than (if I remember my iptables) allowing up to 4 hits on this service withing 180 seconds with SYN flag set.

So no direct mapping but it gives you the added benefit of not allowing more than one connection from a given host, for example.