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OpenCloudOS / nettrace

nettrace is a eBPF-based tool to trace network packet and diagnose network problem.
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Does nettrace support ipv6? If not, will ipv6 packet tracking be supported in the future? #18

Closed Jcm22 closed 1 year ago

menglongdong commented 1 year ago

Hello, ipv6 is supported by nettrace for now. However, the kernel function that we trace in IPv6 packet path is not complete. I added some kernel function this time, now ipv6 packet of TCP can be traced in the general code path:

sudo ./src/nettrace -p ipv6 --diag
begin trace...
***************** ffff8882975e14e0 ***************
[773788.831238] [ip6_output          ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831255] [ip6_finish_output   ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831259] [ip6_finish_output2  ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831263] [__dev_queue_xmit    ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831266] [dev_hard_start_xmit ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831271] [enqueue_to_backlog  ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831285] [__netif_receive_skb_core] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831295] [ipv6_rcv            ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831299] [ip6_rcv_core        ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831307] [nf_hook_slow        ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S *ipv6 in chain: NOTICE*
[773788.831315] [tcp_v6_rcv          ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831321] [inet6_lookup_listener] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S *tcp port is not listened*
[773788.831335] [tcp_v6_send_reset   ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S
[773788.831406] [kfree_skb           ] TCP: :::::::0001:60864 -> :::::::0001:9999 seq:3443414921, ack:0, flags:S *packet is dropped by kernel*
---------------- ANALYSIS RESULT ---------------------
[1] WARNING happens in inet6_lookup_listener(tcp-in):
        tcp port is not listened
    fix advice:
        check your target tcp port

[2] ERROR happens in kfree_skb(life):
        packet is dropped by kernel
    location:
        tcp_v6_rcv+0x52

And the more kernel function we trace on IPv6 will be added in the future, as IPv6 is also being used in our product too.