Classification: Confidential Hello. GTP-U tunnel packet containing inner packets with TTL < 63 or > 79 are not recognised as IP packets, due to wrong parsing. Packets are then dropped as "receive tunnel port is not found" (see logs).
The start of the inner IP header is wrong because gtpu_hlen includes also 8 bytes from the tunnel UDP header. ip = ALIGNED_CAST(struct ip_header *, (char *)gtph + gtpu_hlen); and so IP_VER(ip->ip_ihl_ver) is actually the TTL byte. https://github.com/openvswitch/ovs/blob/20a7654d240f2af5da73a32c1791442e6aac0101/lib/netdev-native-tnl.c#L57 https://github.com/openvswitch/ovs/blob/20a7654d240f2af5da73a32c1791442e6aac0101/lib/netdev-native-tnl.c#L729-L741 2024-01-23T10:59:14.407Z|00068|native_tnl|WARN|GTP-U: Receive non-IP packet. 2024-01-23T10:59:14.407Z|00069|dpif_netdev|DBG|ovs-netdev: miss upcall: recirc_id(0),dp_hash(0),skb_priority(0),tunnel(tun_id=0x1388,src=198.18.0.1,dst=198.18.0.2,ttl=64,tp_src=2152,tp_dst=2152,gtpu(flags=0x30,msgtype=255),flags(csum|key)),in_port(4),skb_mark(0),ct_state(0),ct_zone(0),ct_mark(0),ct_label(0),packet_type(ns=0,id=0),eth(src=40:00:3d:01:5e:97,dst=45:00:00:54:bf:0e),eth_type(0x1000) vlan_tci=0x0000,dl_src=40:00:3d:01:5e:97,dl_dst=45:00:00:54:bf:0e,dl_type=0x1000 2024-01-23T10:59:14.408Z|00070|tunnel|WARN|receive tunnel port not found (tun_src=198.18.0.1,tun_dst=198.18.0.2,tun_ipv6_src=::,tun_ipv6_dst=::,tun_gbp_id=0,tun_gbp_flags=0,tun_tos=0,tun_ttl=64,tun_erspan_ver=0,gtpu_flags=0x30,gtpu_msgtype=255,tun_flags=csum,in_port=4,vlan_tci=0x0000,dl_src=40:00:3d:01:5e:97,dl_dst=45:00:00:54:bf:0e,dl_type=0x1000) Git commit: cc670e741170972de5da4cfad294991468954df BR Michele ::DISCLAIMER:: ________________________________ The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects. ________________________________
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