Simple GTP Gateway example

This example make use of libgtpnl from osmocom to create a GTP tunnel and send some traffic.

Install dependencies

apt-get update && apt-get install -y autoconf libtool pkg-config

Setup

First, get the example:

git clone https://github.com/abousselmi/gtp-gw.git
cd gtp-gw

Second, you need to clone libgtpnl and compile it:

git clone https://git.osmocom.org/libgtpnl
cd libgtpnl
autoreconf -fi
./configure && make
sudo make install
sudo ldconfig

Now we need to copy the example script where we have the gtp wrappers:

cp ../gtpgw.sh ./tools
cd tools

Now you can run the example and enjoy:

./gtpgw.sh start

To destroy everything, you can do:

./gtpgw.sh stop

Sample output

./gtpgw.sh start
[INFO] create veth pairs
[INFO] create network namespaces
[INFO] attribute each veth pair to its correspondent netns
[INFO] set ip addresses of veth pairs and loopbacks
[INFO] enable veth and lo interfaces
[INFO] create gtp devices (run in bg mode)
[INFO] configure mtu of gtp devices
WARNING: attaching dummy socket descriptors. Keep this process running for testing purposes.
WARNING: attaching dummy socket descriptors. Keep this process running for testing purposes.
[INFO] create gtp tunnels
[INFO] version 1 tei 200/100 ms_addr 192.168.0.200 sgsn_addr 172.100.0.200
[INFO] version 1 tei 100/200 ms_addr 192.168.0.100 sgsn_addr 172.100.0.100
[INFO] configure routes using gtp devices

You can go for e.g.:
  ip netns exec ns-gtp-100 ping 192.168.0.200
  ip netns exec ns-gtp-200 ping 192.168.0.100

Using tshark you will see ICMP pckets encapsulated in GTP

Credits

• Kentaro Ebisawa libgtpnl (gtpc) tutorial
• osmocom gtpu
• osmocom gtpc