RE: Rules For MailServer

["Rob Sterenborg" <rob@sterenborg.info>]

> Yes, using RBLSMTPD there are zen,spamcop & another 2
> RBL sites i have been configured. even though the lots
> of unwanted connection is established...

Yes, well, you can rate-limit smtp connections, but since you probably can't
know where legitimate email comes from, you'll also be limiting legitimate
connections. However, maybe Qmail can rate-limit smtp connections too in a
nicer way (I don't know Qmail, but I know that Postfix has a "stress" config
these days).

You can try using the limit match:
$ipt -A INPUT -i eth1 -m state --state NEW -p tcp --dport 25 \
  -m limit --limit 1/second -j ACCEPT
$ipt -A INPUT -i eth1 -m state --state NEW -p tcp --dport 25 \
  -j REJECT

Or using the connlimit match:
$ipt -A INPUT -i eth1 -m state --state NEW -p tcp --dport 25 \
  -m connlimit --connlimit-above 2 -j REJECT

They do different things, but one of them may be useful for you.
See "man iptables".


Grts,
Rob

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