Traffic Forwarder using IPTables: Difference between revisions
From Leo's Notes
This page was last edited on 6 July 2020, at 20:27.
No edit summary |
mNo edit summary |
||
| (9 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
To make a | To make a Linux host act as the gateway for a NAT using IPTables, there are a few steps to do: | ||
1. Enable IP forwarding in the kernel | |||
2. Create a route so the NAT'ed network is routed via the internal interface | |||
3. Create a NAT on the external interface | |||
4. Allow traffic from the internal interface to forward through to the external interface. | |||
These can be accomplished by running the following: | |||
{{highlight|lang=terminal|code= | |||
## Enables forwarding. Same effect with 'sysctl net.ipv4.ip_forward=1' | |||
# echo 1 > /proc/sys/net/ipv4/ip_forward | |||
## Define $INSIDE as the interface going into the NAT | |||
## Define $OUTSIDE as the interface going to the internet | |||
[[Category:Linux]] | ## Route traffic destined to 10.10.2.0/24 to $INSIDE | ||
# route add -net 10.10.2.0/24 dev $INSIDE | |||
## Masquerade traffic going to $OUTSIDE | |||
# iptables -t nat -A POSTROUTING -o $OUTSIDE -j MASQUERADE | |||
## Forward traffic coming from $INSIDE | |||
# iptables -A FORWARD -i $INSIDE -j ACCEPT | |||
}} | |||
Devices on the NAT should use this Linux host as its gateway. | |||
You will probably want to run {{code|iptables-save}} to make the changes persistent after testing. | |||
{{Navbox Linux}}[[Category:Linux]] | |||
[[Category:Networking]] | |||
Latest revision as of 20:27, 6 July 2020
To make a Linux host act as the gateway for a NAT using IPTables, there are a few steps to do: 1. Enable IP forwarding in the kernel 2. Create a route so the NAT'ed network is routed via the internal interface 3. Create a NAT on the external interface 4. Allow traffic from the internal interface to forward through to the external interface.
These can be accomplished by running the following:
## Enables forwarding. Same effect with 'sysctl net.ipv4.ip_forward=1'
# echo 1 > /proc/sys/net/ipv4/ip_forward
## Define $INSIDE as the interface going into the NAT
## Define $OUTSIDE as the interface going to the internet
## Route traffic destined to 10.10.2.0/24 to $INSIDE
# route add -net 10.10.2.0/24 dev $INSIDE
## Masquerade traffic going to $OUTSIDE
# iptables -t nat -A POSTROUTING -o $OUTSIDE -j MASQUERADE
## Forward traffic coming from $INSIDE
# iptables -A FORWARD -i $INSIDE -j ACCEPT
Devices on the NAT should use this Linux host as its gateway.
You will probably want to run iptables-save to make the changes persistent after testing.