Dear @fasferraz
Everything works great up until the point I try to send some IP data across the GTP-U tunnel (towards the SGW).
S1 setup succeeds
Attach succeeds
2022-12-27 18:56:03.207215: S1AP: sending S1SetupRequest |
2022-12-27 18:56:03.217254: S1AP: S1SetupResponse received |
2022-12-27 18:56:04.751138: S1AP: sending InitialUEMessage |
2022-12-27 18:56:04.857392: S1AP: DownlinkNASTransport received |
2022-12-27 18:56:04.860707: NAS: AuthenticatonRequest received |
2022-12-27 18:56:04.865603: S1AP: sending UplinkNASTransport |
2022-12-27 18:56:04.875660: S1AP: DownlinkNASTransport received |
2022-12-27 18:56:04.878713: NAS: SecurityMode received |
2022-12-27 18:56:04.928814: NAS: sending SecurityModeComplete |
2022-12-27 18:56:04.931396: S1AP: sending UplinkNASTransport |
2022-12-27 18:56:05.039040: S1AP: InitialContextSetupRequest received |
2022-12-27 18:56:05.041977: S1AP: sending InitialContextSetupResponse |
2022-12-27 18:56:05.044763: NAS: AttachAccept received |
2022-12-27 18:56:05.047482: [('apn', 'dyn.delta')] |
2022-12-27 18:56:05.050234: [('pdn type value', 1), ('ipv4', '10.45.0.4')] |
2022-12-27 18:56:05.057832: [('type of identity', 6), ('mcc', 101), ('mnc', 10), ('mme group id', 100), ('m |
2022-12-27 18:56:05.057832: me code', 101), ('m-tmsi', 69), ('s-tmsi', b'e\x00\x00\x00E')] |
2022-12-27 18:56:05.060878: NAS: sending AttachComplete |
2022-12-27 18:56:05.101081: S1AP: sending UplinkNASTransport
After this, a tun1 named interface is already present with IP 10.45.0.4 set.
I add the proper route back: ip route add 10.45.0.0/24 dev tun1
When I try to ping 10.45.0.1 (the SGW side) no response is coming back, tshark records ICMP requests outside of the tunnel:
Capturing on 'tun1'
1 0.000000000 10.45.0.4 โ 10.45.0.1 ICMP 84 Echo (ping) request id=0x0004, seq=122/31232, ttl=64
2 1.023971084 10.45.0.4 โ 10.45.0.1 ICMP 84 Echo (ping) request id=0x0004, seq=123/31488, ttl=64
3 2.047980988 10.45.0.4 โ 10.45.0.1 ICMP 84 Echo (ping) request id=0x0004, seq=124/31744, ttl=64
4 3.071968997 10.45.0.4 โ 10.45.0.1 ICMP 84 Echo (ping) request id=0x0004, seq=125/32000, ttl=64
5 4.095967761 10.45.0.4 โ 10.45.0.1 ICMP 84 Echo (ping) request id=0x0004, seq=126/32256, ttl=64
When I try to ping 10.45.0.4 from the SGW, the GTP-U encapsulated packets are arriving correctly, but no response:
Capturing on 'ens18'
1 0.000000000 10.253.250.51 โ 10.253.250.221 GTP 54 Echo request
2 0.000388885 10.253.250.221 โ 10.253.250.51 GTP 56 Echo response
3 0.577967074 10.45.0.1 โ 10.45.0.4 GTP <ICMP> 134 Echo (ping) request id=0x1a28, seq=1/256, ttl=64
4 1.579006583 10.45.0.1 โ 10.45.0.4 GTP <ICMP> 134 Echo (ping) request id=0x1a28, seq=2/512, ttl=64
5 2.579048708 10.45.0.1 โ 10.45.0.4 GTP <ICMP> 134 Echo (ping) request id=0x1a28, seq=3/768, ttl=64
6 3.580070569 10.45.0.1 โ 10.45.0.4 GTP <ICMP> 134 Echo (ping) request id=0x1a28, seq=4/1024, ttl=64
7 4.580065463 10.45.0.1 โ 10.45.0.4 GTP <ICMP> 134 Echo (ping) request id=0x1a28, seq=5/1280, ttl=64
Seemingly every works a it should, the routes are correct, IPs are correct, yet the userplane part is not passing.
Firewall is disabled on both sides, IP_forwarding is enabled on both sides.