| #!/bin/sh |
| # |
| # Firewall script for GGSN |
| # |
| # Uses $IFGN (eth0) as the Gn interface (Gn) and |
| # $IFGI (eth1) as the Gi interface. |
| # |
| # SUMMARY |
| # * All connections originating from GGSN are allowed. |
| # * Incoming ssh, GTPv0 and GTPv1 is allowed on the Gn interface. |
| # * Incoming ssh is allowed on the Gi interface. |
| # * Forwarding is allowed to and from the Gi interface, but disallowed |
| # to and from the Gn interface. |
| # * Masquerede on Gi interface. |
| |
| IPTABLES="/sbin/iptables" |
| IFGN="eth0" |
| IFGI="eth1" |
| |
| $IPTABLES -P INPUT DROP |
| $IPTABLES -P FORWARD ACCEPT |
| $IPTABLES -P OUTPUT ACCEPT |
| |
| #Allow related and established on all interfaces (input) |
| $IPTABLES -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT |
| |
| #Allow releated, established, GTP and ssh on $IFGN. Reject everything else. |
| $IPTABLES -A INPUT -i $IFGN -p tcp -m tcp --dport 22 --syn -j ACCEPT |
| $IPTABLES -A INPUT -i $IFGN -p udp -m udp --dport 2123 -j ACCEPT |
| $IPTABLES -A INPUT -i $IFGN -p udp -m udp --dport 2152 -j ACCEPT |
| $IPTABLES -A INPUT -i $IFGN -p udp -m udp --dport 3386 -j ACCEPT |
| $IPTABLES -A INPUT -i $IFGN -j REJECT |
| |
| #Allow related, established and ssh. Drop everything else. |
| $IPTABLES -A INPUT -i $IFGI -p tcp -m tcp --dport 22 --syn -j ACCEPT |
| $IPTABLES -A INPUT -i $IFGI -j DROP |
| |
| # Masquerade everything going out on $IFGI |
| $IPTABLES -t nat -A POSTROUTING -o $IFGI -j MASQUERADE |
| |
| #Allow everything on loopback interface. |
| $IPTABLES -A INPUT -i lo -j ACCEPT |
| |
| # Drop everything to and from $IFGN (forward) |
| $IPTABLES -A FORWARD -i $IFGN -j DROP |
| $IPTABLES -A FORWARD -o $IFGN -j DROP |
| |
| |