Using GTP on Linux with libgtpnl
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The document discusses configuring GTP tunnels on Linux using the libgtpnl library. Key points: - Linux kernels since 4.7 include GTP tunnel endpoint functionality in the gtp.c driver - Libgtpnl provides tools to configure GTP tunnels via netlink without a control plane - Configuration involves creating veth interfaces, loopbacks, GTP devices, and tunnels between endpoints using TEIDs and IP addresses
![• Linux has kernel level implementation of GTP tunnel endpoint
• Since Linux Kernel 4.7
• “drivers/net/gtp.c”
• https://github.com/torvalds/linux/blob/master/Documentation/networking/gtp.txt
• https://osmocom.org/projects/linux-kernel-gtp-u/wiki
• Features
• Encap / Decap of GTP-U (GTP User Plane)
• GTP-U v0 [GSM TS 09.60] and v1 [3GPP TS 29.281]
• IPv4 only : No GTP over IPv6 nor IPv6 user traffic on GTP payload
Since GTPv0 is deprecated, this slide will only show GTPv1
Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 2
GTP on Linux](https://image.slidesharecdn.com/linuxgtp-libgtpnl-20181231-181231052941/85/Using-GTP-on-Linux-with-libgtpnl-2-320.jpg)
![Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 4
Building libgtpnl
> Install prerequisites
$ sudo apt install libmnl-dev autoconf libtool
> Clone source code, configure and build
$ git clone git://git.osmocom.org/libgtpnl.git
$ cd libgtpnl
libgtpnl$ autoreconf –fi
libgtpnl$ ./configure
libgtpnl$ make
libgtpnl$ sudo make install
libgtpnl$ sudo ldconfig
> Check gtp-link and gtp-tunnel are built
libgtpnl$ sudo -s
libgtpnl# cd tools
libgtpnl/tools# ./gtp-link
Usage: ./gtp-link <add|del> <device>
libgtpnl/tools# ./gtp-tunnel
./gtp-tunnel <add|delete|list> [<options,...>]
> If LIBMNL error happens during ./configure, do below.
./configure: line 2950: syntax error near unexpected token `LIBMNL,'
./configure: line 2950: `PKG_CHECK_MODULES(LIBMNL, libmnl >= 1.0.0)’
$ whereis libmnl
libmnl: /usr/lib/x86_64-linux-gnu/libmnl.a /usr/lib/x86_64-linux-
gnu/libmnl.so /usr/local/lib/libmnl.so /usr/local/lib/libmnl.la
/usr/include/libmnl
$ ldd /usr/local/lib/libmnl.so
linux-vdso.so.1 (0x00007fffdadf9000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f6f9af5d000)
/lib64/ld-linux-x86-64.so.2 (0x00007f6f9b554000)
> make sure you run autoreconf again before running ./configure
libgtpnl$ autoreconf –fi
libgtpnl$ ./configure](https://image.slidesharecdn.com/linuxgtp-libgtpnl-20181231-181231052941/85/Using-GTP-on-Linux-with-libgtpnl-4-320.jpg)
Using GTP on Linux with libgtpnl
- 1. Using GTP on Linux ( libgtpnl ) SRv6 Consortium, Data plane Study Group Kentaro Ebisawa | Twitter: @ebiken Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 1
- 2. • Linux has kernel level implementation of GTP tunnel endpoint • Since Linux Kernel 4.7 • “drivers/net/gtp.c” • https://github.com/torvalds/linux/blob/master/Documentation/networking/gtp.txt • https://osmocom.org/projects/linux-kernel-gtp-u/wiki • Features • Encap / Decap of GTP-U (GTP User Plane) • GTP-U v0 [GSM TS 09.60] and v1 [3GPP TS 29.281] • IPv4 only : No GTP over IPv6 nor IPv6 user traffic on GTP payload Since GTPv0 is deprecated, this slide will only show GTPv1 Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 2 GTP on Linux
- 3. • You can use netlink to configure GTP Kernel module. • The most simple way is to use tools in libgtpnl • No need to run control plane software. • http://git.osmocom.org/libgtpnl/ • https://osmocom.org/projects/linux-kernel-gtp-u/wiki/Libgtpnl Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 3 How to configure GTP-U on Linux
- 4. Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 4 Building libgtpnl > Install prerequisites $ sudo apt install libmnl-dev autoconf libtool > Clone source code, configure and build $ git clone git://git.osmocom.org/libgtpnl.git $ cd libgtpnl libgtpnl$ autoreconf –fi libgtpnl$ ./configure libgtpnl$ make libgtpnl$ sudo make install libgtpnl$ sudo ldconfig > Check gtp-link and gtp-tunnel are built libgtpnl$ sudo -s libgtpnl# cd tools libgtpnl/tools# ./gtp-link Usage: ./gtp-link <add|del> <device> libgtpnl/tools# ./gtp-tunnel ./gtp-tunnel <add|delete|list> [<options,...>] > If LIBMNL error happens during ./configure, do below. ./configure: line 2950: syntax error near unexpected token `LIBMNL,' ./configure: line 2950: `PKG_CHECK_MODULES(LIBMNL, libmnl >= 1.0.0)’ $ whereis libmnl libmnl: /usr/lib/x86_64-linux-gnu/libmnl.a /usr/lib/x86_64-linux- gnu/libmnl.so /usr/local/lib/libmnl.so /usr/local/lib/libmnl.la /usr/include/libmnl $ ldd /usr/local/lib/libmnl.so linux-vdso.so.1 (0x00007fffdadf9000) libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f6f9af5d000) /lib64/ld-linux-x86-64.so.2 (0x00007f6f9b554000) > make sure you run autoreconf again before running ./configure libgtpnl$ autoreconf –fi libgtpnl$ ./configure
- 5. Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 5 Configure GTP endpoints inside netns netns: default netns: ns2 veth1 172.0.0.1/24 veth2 172.0.0.2/24 gtp1 (gtp device) gtp2 (gtp device) lo (loopback) 172.99.0.2/32 lo (loopback) 172.99.0.1/32 TEID# 100 TEID#200 TEID# 100 TEID#200 $ sudo –s ip link add veth1 type veth peer name veth2 ip addr add 172.0.0.1/24 dev veth1 ip link set veth1 up ip addr add 172.99.0.1/32 dev lo > Create gtp device ./gtp-link add gtp1 > Open a new console and configure tunnel (PDP session) ./gtp-tunnel add gtp1 v1 200 100 172.99.0.2 172.0.0.2 ip route add 172.99.0.2/32 dev gtp1 $ sudo –s ip netns add ns2 ip link set veth2 netns ns2 ip netns exec ns2 ip addr add 172.0.0.2/24 dev veth2 ip netns exec ns2 ip link set veth2 up ip netns exec ns2 ip addr add 172.99.0.2/32 dev lo ip netns exec ns2 ip link set lo up > Create gtp device ip netns exec ns2 ./gtp-link add gtp2 > Open a new console and configure tunnel (PDP session) ip netns exec ns2 ./gtp-tunnel add gtp2 v1 100 200 172.99.0.1 172.0.0.1 ip netns exec ns2 ip route add 172.99.0.1/32 dev gtp2
- 6. Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 6 command to configuration mapping (gtp1 => gtp2) netns: default netns: ns2 veth1 172.0.0.1/24 veth2 172.0.0.2/24 gtp1 (gtp device) gtp2 (gtp device) lo (loopback) 172.99.0.2/32 lo (loopback) 172.99.0.1/32 TEID# 100 TEID#200 TEID# 100 TEID#200 ./gtp-tunnel add gtp1 v1 200 100 172.99.0.2 172.0.0.2 ./gtp-tunnel add <gtp device> <v1> <i_tei> <o_tei> <ms-addr> <sgsn-addr> gtp device i_tei o_tei sgsn-addr ms-addr output TEID input TEID Tunnel Endpoint MS: Mobile Station (UE in LTE) Packet with dst IP = <ms-addr> will be encapsulated in GTP packet with dst IP = <sgsn-addr> and TEID = <o_tei>
- 7. Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 7 Confirm tunnel (PDP session) configuration netns: default netns: ns2 veth1 172.0.0.1/24 veth2 172.0.0.2/24 gtp1 (gtp device) gtp2 (gtp device) lo (loopback) 172.99.0.2/32 lo (loopback) 172.99.0.1/32 TEID# 100 TEID#200 TEID# 100 TEID#200 libgtpnl/tools# ./gtp-tunnel list version 1 tei 200/100 ms_addr 172.99.0.2 sgsn_addr 172.0.0.2 libgtpnl/tools# ip netns exec ns2 ./gtp-tunnel list version 1 tei 100/200 ms_addr 172.99.0.1 sgsn_addr 172.0.0.1
- 8. Using GTP on Linux (libgtpnl) | SRv6 Consortium, Data plane Study Group | 2018/12/31 (rev 0) 8 GTP Packet Dump netns: default netns: ns2 veth1 172.0.0.1/24 veth2 172.0.0.2/24 gtp1 (gtp device) gtp2 (gtp device) lo (loopback) 172.99.0.2/32 lo (loopback) 172.99.0.1/32 TEID# 100 TEID#200 TEID# 100 TEID#200 # ping 172.99.0.2 ICMP echo request ICMP echo reply