Hi, Following the directions for setting up bridged networking in the red hat virtualization guide and libvirt wiki, I set the following kernel parameters to 0 on a RHEL 5.5 server. net.bridge.bridge-nf-call-ip6tables net.bridge.bridge-nf-call-iptables net.bridge.bridge-nf-call-arptables Unfortunately, doing this broke the port forwarding I'd set up for VMs on my NAT networks, e.g. iptables -I FORWARD -d 192.168.122.2 -i eth0 -p tcp -m tcp --dport 80 -m state --state NEW -j ACCEPT iptables -t nat -I PREROUTING -i eth0 -p tcp -m tcp --dport 8080 -j DNAT --to-destination 192.168.122.2:80 Before I run sysctl to change those values, nmap shows port 8080 as open. Afterwards, nmap shows it as filtered. Using sysctl to set those values to 1 did not undo the change, the port still showed as filtered. I had to reboot to open the port again. Creating an iptables rule to accept traffic on bridged devices, i.e. iptables -I FORWARD -m physdev --physdev-is-bridged -j ACCEPT did not not cause this problem. I am wondering if breaking the FORWARD and PREROUTING rules I set up to do port forwarding is to be expected when those net.bridge parameters are set to 1. If so, I think this should be mentioned in the libvirt wiki and red hat documentation. It can't be that uncommon for a single server to host guests with a mix of with bridged and NAT networking. -- Brian Pitts Systems Administrator | EuPathDB Bioinformatics Resource Center 706-542-1447 | bdp(a)uga.edu | http://eupathdb.org