I know iptables
+ xtables
can do it in more recent versions using the TEE target supplied by the xtables-addon package for iptables. However, the kernel in CentOS 5.9 is 2.6.18 and this version is not sufficient for any version of xtables-addons (2.6.19 is sufficient, however, I can't upgrade the kernel/OS on this box of mine).
So, is there some other tool that can do it? I need to mirror UDP packets to a different host on the same network.