Packets are not arrived at tunnel setup by libgtpnl
Hi guys, I'm using libgtpnl tools (gtp-link, gtp-tunnel) to setup a tunnel in my local machines. I was able to setup gtp link to 2152 port as well as gtp tunnel. I have pre-recorded GTP packets with correct teid and IP address as well as chksum and port to send to 2152. However I can not see any packets in gtp link device when using tcpdump. By add some messages in gtp module, I notice that the function gtp1u_udp_encap_recv in gtp.c kernel file was never been called if I send packet with GTP headers. However, that function is called if I send normal UDP packet without GTP header. Note that I'm using Ubuntu 14.04 with kernel 4.8.0 lowlatency, the tunnel is on a VM created by Virtualbox using virtio network driver. Any suggestions on how to debug/solve this problem? Many thanks in advances. Best regards Cong.
hi Cong, it would be very useful if you could give a description of what exactly your are trying to achieve, using which particular versions of which software. The kernel GTP module is known-working and has been verified with both OpenGGSN and OsmoSGSN. There are also other users such as OpenAirInterface as well as (as far as I know) ergw. It might be easiest to simply use one of those programs to understnd how the kernel GTP-U driver is used. Also, if you want us to be able to help you, please always include the detailed copy+paste output of the related commands and tools, e.g. the exact gtp-link and gtp-tunnel commands you have been using. -- - Harald Welte <laforge@gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)
Hi Harald and Firat, Thank you very much for your reply. Sorry for not provide detail information when asking question. Lucky me, I am able to solve my problem now. It's because of wrong MAC address in packets that cause gtp device unable to receive. Stupid mistake. Still, I post it here just in case it can help other newbies like me. Thanks and best regards Cong On 11/23/2017 08:30 PM, Harald Welte wrote:
hi Cong,
it would be very useful if you could give a description of what exactly your are trying to achieve, using which particular versions of which software.
The kernel GTP module is known-working and has been verified with both OpenGGSN and OsmoSGSN. There are also other users such as OpenAirInterface as well as (as far as I know) ergw. It might be easiest to simply use one of those programs to understnd how the kernel GTP-U driver is used.
Also, if you want us to be able to help you, please always include the detailed copy+paste output of the related commands and tools, e.g. the exact gtp-link and gtp-tunnel commands you have been using.
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congnt -
Harald Welte