Hi, We recently installed CentOS 6.2 on our cluster. During the installation/debugging of various secondary software, we had disabled iptables. When we re-enabled them, we found that the front-end would no longer X11 forward (although it does so when the iptables are off). What do we need to set in the iptables to permit X11 forwarding? Currently we're using iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P OUTPUT ACCEPT iptables -A INPUT -m limit --limit 15/minute -j LOG --log-level 7 --log-prefix "Dropped by firewall: " iptables -A INPUT -i eth1 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p tcp --dport 8080 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p tcp --dport 6000 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p tcp --dport 6001 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p tcp --dport 6002 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p tcp --dport 6003 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p tcp --dport 6004 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p tcp --dport 6005 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p udp --dport 177 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p udp --dport 6000 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth1 -p udp -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A INPUT -i eth1 -p tcp -m state --state ESTABLISHED,RELATED -j ACCEPT -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Pat Haley Email: phaley at mit.edu Center for Ocean Engineering Phone: (617) 253-6824 Dept. of Mechanical Engineering Fax: (617) 253-8125 MIT, Room 5-213 http://web.mit.edu/phaley/www/ 77 Massachusetts Avenue Cambridge, MA 02139-4301