ipt_unclean: TCP flags bad: 4

From: Alan J. Wylie (alan.nospam@glaramara.freeserve.co.uk)
Date: Sun Jul 22 2001 - 10:27:26 EST

I've just upgraded to 2.4.7, and I'm getting lots of errors:

ipt_unclean: TCP flags bad: 4

I only see them when my ppp link is up - pppd version 2.4.0

Looking at ipt_unclean.c it seems that this message will be generated
when I send a packet with flags set to RST only.

I've run a ppp session with the pppd option "record" turned on, and
analysed the output with "ethereal". This is indeed what is on the
wire. I'm no expert on TCP I'm afraid. The complete TCP stream

No. Time Source Destination Protocol Info

129 12.800000 news.svr.pol.co.uk TCP
    1148 > nntp [SYN] Seq=3684831495 Ack=0 Win=5840 Len=0

131 12.900000 news.svr.pol.co.uk TCP
    nntp > 1148 [SYN, ACK] Seq=2607886663 Ack=3684831496 Win=32736 Len=0

137 13.300000 news.svr.pol.co.uk TCP
    1148 > nntp [FIN, ACK] Seq=3684831502 Ack=2607887466 Win=7090 Len=0

142 13.400000 news.svr.pol.co.uk TCP
    1148 > nntp [RST] Seq=3684831503 Ack=0 Win=0 Len=0

Alan J. Wylie                        http://www.glaramara.freeserve.co.uk/
"Perfection [in design] is achieved not when there is nothing left to add,
but rather when there is nothing left to take away."
  Antoine de Saint-Exupery
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

This archive was generated by hypermail 2b29 : Mon Jul 23 2001 - 21:00:15 EST