[pptp-server] PPTP mppe woes

Jerry Vonau jvonau at shaw.ca
Mon Jul 8 08:15:19 CDT 2002


Matt:

Looks like pppd is trying to do call back. Can you add 'debug' to the options 
file,
and capture the " ipcp handshake". What is the client? Is callback turned on in 
the client?


root at egg ppp-2.4.1]# Jul  7 12:08:56 egg kernel: device ppp0 entered
promiscuous mode
Jul  7 12:10:17 egg pptp[23708]: log[pptp_conn_close:pptp_ctrl.c:307]:
Closing PPTP connection
Jul  7 12:10:17 egg pptp[23708]: log[call_callback:pptp_callmgr.c:88]:
Closing connection


Jerry Vonau

-----Original Message-----
From:	Matt Kirk [SMTP:mkirk at sonic.net]
Sent:	Monday, July 08, 2002 02:24 AM
To:	'pptp-server at lists.schulte.org'
Subject:	[pptp-server] PPTP mppe woes

I am having a problem passing traffic to a pptp server (Watchguard Firebox).
I can connect fine, but as soon as the first packet tries to go across the
connection I get no gre response from the server.  I have included the log
file, an lsmod, a tcpdump and top info.  I wasn't able to find ppp_mppe.o
anywhere but mppe.o is loaded...  What am I doing wrong?


-- lsmod
[root at egg ppp-2.4.1]# lsmod
Module                  Size  Used by    Tainted: P
mppe                   24992   0  (autoclean)
ppp_async               7488   0  (autoclean)
ppp_generic            17608   0  [mppe ppp_async]
slhc                    5880   0  [ppp_generic]
tulip                  39200   1


--  Start and end info from log file
[root at egg ppp-2.4.1]# /opt/src/pptp-linux-1.1.0-1/pptp-command start
Jul  7 12:08:16 egg pptp[23708]:
log[pptp_dispatch_ctrl_packet:pptp_ctrl.c:580]: Client connection
established.
Jul  7 12:08:17 egg pptp[23708]:
log[pptp_dispatch_ctrl_packet:pptp_ctrl.c:707]: Outgoing call established
(call ID 0, peer's call ID 1).
Jul  7 12:08:17 egg pppd[23710]: pppd 2.4.1 started by root, uid 0
Jul  7 12:08:17 egg pppd[23710]: Using interface ppp0
Jul  7 12:08:17 egg pppd[23710]: Connect: ppp0 <--> /dev/pts/5
Jul  7 12:08:20 egg pppd[23710]: Remote message:
S=2aa343c8173d023bd125398d093cea3b71387705
Jul  7 12:08:21 egg pppd[23710]: MPPE 128 bit, stateless compression enabled
Jul  7 12:08:21 egg pppd[23710]: local  IP address 208.204.117.91
Jul  7 12:08:21 egg pppd[23710]: remote IP address 208.204.117.119
Route: add -net 209.204.177.0/25 dev ppp0 added
All routes added.
Tunnel Sonic.net-VPN is active on ppp0.  IP Address: 208.204.117.91
Installed /etc/resolv.conf.pptp as /etc/resolv.conf
[root at egg ppp-2.4.1]# Jul  7 12:08:56 egg kernel: device ppp0 entered
promiscuous mode
Jul  7 12:10:17 egg pptp[23708]: log[pptp_conn_close:pptp_ctrl.c:307]:
Closing PPTP connection
Jul  7 12:10:17 egg pptp[23708]: log[call_callback:pptp_callmgr.c:88]:
Closing connection
Jul  7 12:10:19 egg pppd[23710]: Hangup (SIGHUP)
Jul  7 12:10:19 egg pppd[23710]: Modem hangup
Jul  7 12:10:19 egg pppd[23710]: Connection terminated.
Jul  7 12:10:19 egg pppd[23710]: Connect time 2.1 minutes.
Jul  7 12:10:19 egg pppd[23710]: Sent 310494120 bytes, received 70 bytes.
Jul  7 12:10:19 egg kernel: device ppp0 left promiscuous mode
Jul  7 12:10:19 egg kernel: device ppp0 entered promiscuous mode
Jul  7 12:10:19 egg pppd[23710]: Exit.

This is not right: Sent 310494120 bytes, received 70 bytes.
It is always 2.1 minutes.


---tcpdump results after first ping packet is sent.

12:09:17.193992 208.204.159.47.33909 > 208.204.117.119.1723: P
2373538781:237353
8797(16) ack 3196192242 win 5840: pptp CTRL_MSGTYPE=ECHORQ [|pptp] (DF)
12:09:17.194137 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:13
ppp:
(DF)
12:09:17.194181 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:14
ppp:
(DF)
12:09:17.194219 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:15
ppp:
(DF)
12:09:17.194260 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:16
ppp:
(DF)
12:09:17.194304 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:17
ppp:
(DF)
12:09:17.194350 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:18
ppp:
(DF)
12:09:17.194397 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:19
ppp:
(DF)
12:09:17.194452 208.204.159.47 > 208.204.117.119: (frag 33673:28 at 312)
12:09:17.194477 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:20
ppp:
(frag 33673:312 at 0+)
12:09:17.194521 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:21
ppp:
(DF)
12:09:17.194555 208.204.159.47 > 208.204.117.119: (frag 33674:38 at 312)
12:09:17.194579 208.204.159.47 > 208.204.117.119: gre [KSv1] ID:0001 S:22
ppp:
...

This continues until the connection is dropped.


While the above is happening, pptp uses the CPU like mad (not supprising).

  PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
23706 root      15   0   488  488   428 R    98.1  0.0   0:25 pptp
23725 root       9   0  2392 2392  1640 S     0.9  0.4   0:00 vim
 1078 root      10   0 98.9M  34M  2756 R     0.3  6.8 114:02 X
23602 root      11   0  1052 1052   836 R     0.3  0.2   0:02 top
    1 root       8   0   480  480   420 S     0.0  0.0   0:04 init
    2 root       9   0     0    0     0 SW    0.0  0.0   0:00 keventd
    3 root      19  19     0    0     0 RWN   0.0  0.0   0:00 ksoftirqd_CPU0
    4 root       9   0     0    0     0 SW    0.0  0.0   0:00 kswapd
    5 root       9   0     0    0     0 SW    0.0  0.0   0:00 bdflush
    6 root       9   0     0    0     0 SW    0.0  0.0   0:06 kupdated
    7 root       9   0     0    0     0 SW    0.0  0.0   0:00 khubd
    8 root       9   0     0    0     0 SW    0.0  0.0   0:29 kjournald
  135 root       9   0     0    0     0 SW    0.0  0.0   0:00 kjournald
  136 root       9   0     0    0     0 SW    0.0  0.0   0:09 kjournald

--

Matt Kirk - mkirk at sonic.net

Fingerprint = 4B8F 0AB9 63B2 A782 5E46  52C1 79D5 D2F6 A7F8 6F5E

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