TOFCPU information#

How to set up natting?#

Nat (Network address translation) allows a computer to access the internet through another machine (gateway) which has to pass on the traffic. This is usually necessary when we go from one network (e.g. 10.0.1.1/24 to 192.168.1.1/24). So the gateway machine would typically have 2 network interfaces.

  • Step 1: Set the default gateway on the TOF computer

    • Delete the old gateway sudo ip route del default

    • Set the new gateway sudo ip route add default via <GATEWAY IP>

  • Step 2: There are 4 steps which need to be taken to set the gateway macnine to forward ip traffic. This is taken from this article. It will require super user rights.

    • Make sure ip forwarding is allowed echo 1 > /proc/sys/net/ipv4/ip_forward

    • Set up the actual natting, allowing packets to go back and forth `/sbin/iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

`

/sbin/iptables -A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT /sbin/iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT

where eth0 is the external and eth1 the internal network adapter.

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