Restrict IP Connections on Ports 80 and 25 with Iptables

ow do I restrict the number of connections used by a single IP address to my server for port 80 and 25 using iptables? You need to use the connlimit modules which allows you to restrict the number of parallel TCP connections to a server per client IP address (or address block). This is useful to protect your server or vps box against flooding, spamming or content scraping.

Syntax

The syntax is as follows:

/sbin/iptables -A INPUT -p tcp --syn --dport $port -m connlimit --connlimit-above N -j REJECT --reject-with tcp-reset
# save the changes see iptables-save man page, the following is redhat and friends specific command
service iptables save


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