Routing
From Attie's Wiki
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To setup NAT between interfaces eth0 (outside) and tun0 (inside - e.g. a [[OpenVPN|VPN]] server) | To setup NAT between interfaces eth0 (outside) and tun0 (inside - e.g. a [[OpenVPN|VPN]] server) | ||
<source lang="bash"> | <source lang="bash"> | ||
| + | echo 1 > /proc/sys/net/ipv4/ip_forward | ||
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE | iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE | ||
iptables -A FORWARD -i eth0 -o tun0 -m state --state RELATED,ESTABLISHED -j ACCEPT | iptables -A FORWARD -i eth0 -o tun0 -m state --state RELATED,ESTABLISHED -j ACCEPT | ||
Revision as of 12:50, 19 March 2013
Contents |
The Linux `route` command
Below is a list of useful commands
# show the routing table, with numeric addresses route -n # add a default route, through eth0, via 192.168.1.1 route add default dev eth0 gw 192.168.1.1 # add a route to 10.150.0.0/24 through eth0 route add -net 10.150.0.0/24 dev eth0 # add a route to 10.150.0.0/24 through eth0, and the gateway 192.168.0.15 route add -net 10.150.0.0/24 gw 192.168.0.15 dev eth0
SIOCADDRT: No such process
The most unhelpful error possible. It generally means you have done something silly... check:
- Your addresses - e.g. is the gateway you specified actually directly accessible through the interface?
The Linux `iptables` command
# list the current rules (not very useful without -v) iptables -vL
NAT
Setup
To setup NAT between interfaces eth0 (outside) and tun0 (inside - e.g. a VPN server)
echo 1 > /proc/sys/net/ipv4/ip_forward iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE iptables -A FORWARD -i eth0 -o tun0 -m state --state RELATED,ESTABLISHED -j ACCEPT iptables -A FORWARD -i tun0 -o eth0 -j ACCEPT
Teardown
# remove the first item in the 'FORWARD' table, twice - you added two (forward & reverse) iptables -D FORWARD 1 iptables -D FORWARD 1
