ng_mppc_decompress: too many (4094) packets dropped, disabling node

[Gleb Smirnoff]

  Sami,

  I'm trying to reproduce a reordering problem with a new node, and
I've found that:

1) PPTP uses sequencing, that would not pass out of sequence datagram
   to the PPP, and thus to MPPE.
2) L2TP uses sequencing optionally, so the problem in subject may
   appear only on an L2TP link with disabled sequencing.

I wonder how often L2TP is running w/o sequencing control. Can you
please run this script on your mpd box to estimate?

#!/bin/sh

IDS=$(ngctl ls | awk '{ if ($4 == "l2tp") print $6}')
for id in $IDS; do
        id="[$id]:";
        sess=$(ngctl show $id | sed -En 's/.*session_([0-9a-f]+).*/\1/p');
        ngctl msg $id getsessconfig 0x$sess
done

In my small installation I've got only a couple of L2TP clients, and both
use sequencing, so patched code in ng_mppc won't be ever executed.

Rec'd response "getsessconfig" (4) from "[11f]:":
Args:   { session_id=0xafb6 peer_id=0x2fcf control_dseq=1 enable_dseq=1 }
Rec'd response "getsessconfig" (4) from "[f3]:":
Args:   { session_id=0xd34b peer_id=0x2654 control_dseq=1 enable_dseq=1 }

I'd like to explicitly test the code in ng_mppc to make sure, that node
can rekey up to 4096 times and continue operation.

-- 
Totus tuus, Glebius.