icmptunnel

IPv4 over ICMP echo

Build

make

Arguments

-s - run as server -c - run as client -i - outside interface -a - assign address to tunnel interface -z - compress packets with zlib -r - enable ping reply -d - enable debug prints. May be specified twice for full packet printing

Handled signals

SIGUSR1 - Print statistic to stdout

SIGUSR2 - Enable/increase debug level of running application

Run server

Ignore replys for ICMP requests:

sudo echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all

Add MASQUERADE rule to firewall. iface - output interface, network - tunnel network:

sudo iptables -t nat -A POSTROUTING -s <network> -o <iface> -j MASQUERADE

Enable IP forwarding in kernel

sudo echo 1 > /proc/sys/net/ipv4/ip_forward

Run server

sudo ./icmptunnel -s -i eth0 -a 10.20.30.1

Run client

sudo ./icmptunnel -c <server ip> -i eth0 -a 10.20.30.2

Local test

The script will create 3 namespaces (client, gateway, server) and transfer traffic between the client's and server's namespaces

make test