====== Port Mirroring with iptables ====== This article provides the steps for configuring Port Mirroring with suitable commands. Port Mirroring is used to send a copy of packet to destination which was received on the interface depending on the configuration. ===== 1. Commands to mirror ===== We need both inbound and outbound traffic, so using the commands, iptables -t mangle -I PREROUTING -j TEE –gateway 10.20.0.129 **“PREROUTING”** is before routing decision happens iptables -t mangle -I POSTROUTING -j TEE –gateway 10.20.0.129 **“POSTROUTING”** is after routing decision ===== 2. Ping Windows using tcpdump ===== After the rules are applied, ping “Windows XP client” from “Ubuntu” using tcpdump tcpdump -i any -n ===== 3. Viewing the iptables ===== To view the iptables from command line, use the commands. iptables -t mangle -S or iptables -t mangle -L ===== 4. Removing the iptables ===== To remove the rules for iptables, use the following commands. iptables -t mangle -D PREROUTING -j TEE –gateway 10.20.0.129 iptables -t mangle -D POSTROUTING -j TEE –gateway 10.20.0.129