Ok, finally it was quite easy. Install brctl and etherape, then:
brctl addbr br0 brctl stp br0 off brctl addif br0 eth0 brctl addif br0 eth1 echo 1 > /proc/sys/net/ipv4/ip_forward ifconfig eth0 up ifconfig eth1 up ifconfig br0 up service network restart ifconfig br0 XX.YY.ZZ.AA
That is a temporal configuration. If you reboot you have to re-do it. Here is a way to make it persistent: http://www.tldp.org/HOWTO/Ethernet-Bridge-netfilter-HOWTO.html#toc3.3
Finally, (installing if you are in a Windows Box, Xming and Putty and) connecting as root to XX.YY.ZZ.AA with X11 redirection, execute etherape and you will have you remote traffic control.
To make it easier, I will recommend to add the filter: ip and not ((src net XX.YY.ZZ.AA) or dst net XX.YY.ZZ.AA) To avoid the X11 traffic between the server and your box.