preventing ipv6 packets from being generated when creating a gre tunnel

Question

I have a veth device, each side of it is in a different network namespace on the same machine. I am creating a gretap tunnel over this veth. when setting the gretap device to up state I can see a lot of packets like this being generated on the veth:

21:18:46.307865 b6:03:1e:12:cb:75 > 92:41:07:b8:1c:69, IPv4, length 132: (tos 0x0, ttl 1, id 43062, offset 0, flags [DF], proto GRE (47), length 118)
    10.254.1.6 > 10.254.3.0: GREv0, Flags [key present], key=0x96040000, proto TEB (0x6558), length 98
    02:6e:4f:c6:17:0f > 33:33:00:00:00:16, IPv6, length 90: (hlim 1, next-header Options (0) payload length: 36) :: > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 1 group record(s) [gaddr ff02::1:ffc6:170f to_ex { }]
21:18:46.559784 b6:03:1e:12:cb:75 > 92:41:07:b8:1c:69, IPv4, length 132: (tos 0x0, ttl 1, id 43118, offset 0, flags [DF], proto GRE (47), length 118)
    10.254.1.6 > 10.254.3.0: GREv0, Flags [key present], key=0x96040000, proto TEB (0x6558), length 98
    02:6e:4f:c6:17:0f > 33:33:00:00:00:16, IPv6, length 90: (hlim 1, next-header Options (0) payload length: 36) :: > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 1 group record(s) [gaddr ff02::1:ffc6:170f to_ex { }]
21:18:47.115803 b6:03:1e:12:cb:75 > 92:41:07:b8:1c:69, IPv4, length 128: (tos 0x0, ttl 255, id 43220, offset 0, flags [DF], proto GRE (47), length 114)
    10.254.1.6 > 10.254.3.0: GREv0, Flags [key present], key=0x96040000, proto TEB (0x6558), length 94
    02:6e:4f:c6:17:0f > 33:33:ff:c6:17:0f, IPv6, length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) :: > ff02::1:ffc6:170f: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has fe80::6e:4fff:fec6:170f
      unknown option (14), length 8 (1): 
        0x0000:  c0c3 b5ce 75ba
21:18:48.139899 b6:03:1e:12:cb:75 > 92:41:07:b8:1c:69, IPv4, length 132: (tos 0x0, ttl 1, id 43452, offset 0, flags [DF], proto GRE (47), length 118)
    10.254.1.6 > 10.254.3.0: GREv0, Flags [key present], key=0x96040000, proto TEB (0x6558), length 98
    02:6e:4f:c6:17:0f > 33:33:00:00:00:16, IPv6, length 90: (hlim 1, next-header Options (0) payload length: 36) fe80::6e:4fff:fec6:170f > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 1 group record(s) [gaddr ff02::1:ffc6:170f to_ex { }]
21:18:48.139930 b6:03:1e:12:cb:75 > 92:41:07:b8:1c:69, IPv4, length 112: (tos 0x0, ttl 255, id 43453, offset 0, flags [DF], proto GRE (47), length 98)
    10.254.1.6 > 10.254.3.0: GREv0, Flags [key present], key=0x96040000, proto TEB (0x6558), length 78
    02:6e:4f:c6:17:0f > 33:33:00:00:00:02, IPv6, length 70: (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::6e:4fff:fec6:170f > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
      source link-address option (1), length 8 (1): 02:6e:4f:c6:17:0f
        0x0000:  026e 4fc6 170f
21:18:49.131777 b6:03:1e:12:cb:75 > 92:41:07:b8:1c:69, IPv4, length 132: (tos 0x0, ttl 1, id 43685, offset 0, flags [DF], proto GRE (47), length 118)
    10.254.1.6 > 10.254.3.0: GREv0, Flags [key present], key=0x96040000, proto TEB (0x6558), length 98
    02:6e:4f:c6:17:0f > 33:33:00:00:00:16, IPv6, length 90: (hlim 1, next-header Options (0) payload length: 36) fe80::6e:4fff:fec6:170f > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 1 group record(s) [gaddr ff02::1:ffc6:170f to_ex { }]
21:18:52.459788 b6:03:1e:12:cb:75 > 92:41:07:b8:1c:69, IPv4, length 112: (tos 0x0, ttl 255, id 43975, offset 0, flags [DF], proto GRE (47), length 98)
    10.254.1.6 > 10.254.3.0: GREv0, Flags [key present], key=0x96040000, proto TEB (0x6558), length 78
    02:6e:4f:c6:17:0f > 33:33:00:00:00:02, IPv6, length 70: (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::6e:4fff:fec6:170f > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
      source link-address option (1), length 8 (1): 02:6e:4f:c6:17:0f
        0x0000:  026e 4fc6 170f
21:19:01.679749 b6:03:1e:12:cb:75 > 92:41:07:b8:1c:69, IPv4, length 112: (tos 0x0, ttl 255, id 45984, offset 0, flags [DF], proto GRE (47), length 98)
    10.254.1.6 > 10.254.3.0: GREv0, Flags [key present], key=0x96040000, proto TEB (0x6558), length 78
    02:6e:4f:c6:17:0f > 33:33:00:00:00:02, IPv6, length 70: (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::6e:4fff:fec6:170f > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
      source link-address option (1), length 8 (1): 02:6e:4f:c6:17:0f
        0x0000:  026e 4fc6 170f

How can I prevent these? I tried removing the avahi daemon and setting ipv6 autoconf to 0 but it didn't help.

what do you mean by normal traffic? I want to disable these packets being generated when I start the gre interface. — barisdad, Jul 14 '20 at 18:46

score 0 · Answer 1 · answered Jul 13 '20 at 13:20

0

You can try to change the preference for IPv6 by editing /etc/gai.conf. https://serverfault.com/a/93782/30946 Make a backup of the file before any changes. If the file is missing, you just need to create it. See also RFC 3484

answered Jul 13 '20 at 13:20

Mircea Vutcovici

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I am not sure I follow. gai.conf is for configuring dns lookups, right? how is this relevant to router solicitation messages? – barisdad Jul 14 '20 at 18:52
Oh, sorry. You can disable RA: https://superuser.com/a/33204/24085 – Mircea Vutcovici Jul 14 '20 at 20:24

preventing ipv6 packets from being generated when creating a gre tunnel

1 Answers1