Random HDLC packets being received from Cisco

[David Woodhouse]

After a few happy weeks of operation, our leased line (Hostess SV11 running 
syncppp) tends to go AWOL, and it looks like the Cisco at the other end starts 
throwing crap packets at us. I've thrown in some code to dump these packets 
when they arrive, and a selection of them is given below.

Does anyone recognise it, or see how a normal PPP/IP frame could get corrupted 
into something which looks like this?

ifconfig down ; ifconfig up is enough to fix this when it occurs.

If you're looking for IP packets in this, it might help to know that the IP 
addresses are in the range 0xc2cdb8xx. Or it may not - I can't see it.

Jan 12 17:55:54 lisco kernel: hdlc0: lcp output <echo-req id=e3h len=8h 19-6d-94-d6>
Jan 12 17:55:54 lisco kernel: hdlc0: lcp input(O): 8 bytes <echo-reply id=e3h len=8h 7f-ab-b-59>
Jan 12 17:55:55 lisco kernel: Yow an IP frame.
Jan 12 17:55:58 lisco last message repeated 18 times
Jan 12 17:55:59 lisco kernel: hdlc0: invalid input packet <0xff 0x1f 0x0>
Jan 12 17:55:59 lisco kernel: 000: FF 1F 00 00 10 90 14 08 00 00 00 68 63 1B 68 0B
Jan 12 17:55:59 lisco kernel: 010: 40 02 00 F8 6F 03 D0 A6 F5 3F 29 B1 0D F8 AF 55
Jan 12 17:55:59 lisco kernel: 020: C2 6E 33 71 2B 11 00 00 50 2A 41 92 74 53 5A 9A
Jan 12 17:55:59 lisco kernel: 030: 0C 18 48 C2 E6 4F E2 1F 68 03 20 21 E1 7F 23 B1
Jan 12 17:55:59 lisco kernel: 040: B5 05 30 01 00 80 04 20 01 40 82 14 D0 86 0C C0
Jan 12 17:55:59 lisco kernel: 050: 7E 3B A1 35 21 B9
Jan 12 17:55:59 lisco kernel: hdlc0: invalid input packet <0xff 0x1f 0x0>
Jan 12 17:55:59 lisco kernel: 000: FF 1F 00 00 10 90 14 08 00 00 00 68 63 9B 6C 0B
Jan 12 17:55:59 lisco kernel: 010: 40 02 00 F8 6F 03 D0 86 F4 3F 29 B1 0D F8 AF 55
Jan 12 17:55:59 lisco kernel: 020: C2 6E 33 71 2B 11 00 00 50 2A 41 92 74 53 5A 9A
Jan 12 17:55:59 lisco kernel: 030: 0C 18 48 C2 E6 4F E2 1F 68 03 20 21 E1 7F 23 B1
Jan 12 17:55:59 lisco kernel: 040: B5 AD 25 01 00 80 04 20 01 40 82 14 D0 86 0C C0
Jan 12 17:55:59 lisco kernel: 050: 7E 93 AC 35 21 B9
Jan 12 17:55:59 lisco kernel: hdlc0: invalid input packet <0xff 0x1f 0x0>
Jan 12 17:55:59 lisco kernel: 000: FF 1F 00 00 10 90 14 08 00 00 00 58 C2 5E A2 0D
Jan 12 17:55:59 lisco kernel: 010: 40 02 40 62 63 03 40 82 0C 08 A0 9D 14 C0 66 43
Jan 12 17:55:59 lisco kernel: 020: C2 6E 33 71 2B 11 30 81 2C 01 40 32 A1 35 D9 26
Jan 12 17:55:59 lisco kernel: 030: F9 EF 37 01 00 00 00 00 00 00 98 04 00 20 01 40
Jan 12 17:55:59 lisco kernel: 040: 6A AB 1D 00 00 00 08 80 04
Jan 12 17:56:00 lisco kernel: hdlc0: invalid input packet <0xff 0x1f 0x0>
Jan 12 17:56:00 lisco kernel: 000: FF 1F 00 00 10 90 14 08 00 00 00 58 62 9B B4 0D
Jan 12 17:56:00 lisco kernel: 010: 40 02 C0 F6 6F 83 64 83 5C 12 70 B3 2D F9 B7 45
Jan 12 17:56:00 lisco kernel: 020: C2 6E 33 71 DB 16 00 C0 6E 3B 81 64 8B 84 54 7A
Jan 12 17:56:00 lisco kernel: 030: DB 6E 3B 89 14 18 38 91 04 00 98 24 21 11 E0 C7
Jan 12 17:56:00 lisco kernel: 040: 86 1C 30 01 00 00 08 80 04
Jan 12 17:56:00 lisco kernel: hdlc0: invalid input packet <0xff 0x1f 0x0>
Jan 12 17:56:00 lisco kernel: 000: FF 1F 00 00 10 90 14 08 00 00 00 78 63 1B 70 0B
Jan 12 17:56:00 lisco kernel: 010: 40 02 00 F8 6F 03 D0 66 EB 3F 29 B1 0D F8 AF 55
Jan 12 17:56:00 lisco kernel: 020: C2 6E 33 71 2B 11 00 00 50 2A 81 94 84 D4 16 40
Jan 12 17:56:00 lisco kernel: 030: 72 5B 4A C2 96 5C 52 BA D5 06 A8 25 E1 7F 23 D1
Jan 12 17:56:00 lisco kernel: 040: 46 CA 0E 00 00 80 04 20 01 40 82 14 D0 86 0C E0
Jan 12 17:56:00 lisco kernel: 050: 7F 43 82 34 21 B9 D5 3E E9 0F C0 06 30 01 00 40
Jan 12 17:56:00 lisco kernel: 060: 02 20 41
Jan 12 17:56:00 lisco kernel: hdlc0: invalid input packet <0xff 0x1f 0x0>
Jan 12 17:56:00 lisco kernel: 000: FF 1F 00 00 10 90 14 08 00 00 00 68 63 9B 74 0B
Jan 12 17:56:00 lisco kernel: 010: 40 02 00 F8 6F 03 D0 46 F2 3F 29 B1 0D F8 AF 55
Jan 12 17:56:00 lisco kernel: 020: C2 6E 33 71 2B 11 00 00 50 2A 41 92 74 53 5A 9A
Jan 12 17:56:00 lisco kernel: 030: 0C 18 48 C2 E6 4F E2 1F 68 03 20 21 E1 7F 23 B1
Jan 12 17:56:00 lisco kernel: 040: B5 ED 0F 00 00 80 04 20 01 40 82 14 D0 86 0C E0
Jan 12 17:56:00 lisco kernel: 050: 7F 53 82 34 21 B9

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dwmw2