Topic: mppe_compress[0]: osize too small!

[guestHH]

Hi,

Does anybody know what this message in the logfile means?

kernel: mppe_compress[0]: osize too small! (have: 1400 need: 1404)

I get this when making a VPN connection which is not reliable.

TIA
guestHH

[Charlie]

guestHH wrote:

> Does anybody know what this message in the logfile means?
>
> kernel: mppe_compress[0]: osize too small! (have: 1400 need:
> 1404)
>
> I get this when making a VPN connection which is not reliable.

Please, everyone, report all bugs (and new information about known bugs) to smebugs@mitel.com. You can't rely on us picking up information here.

RequestedDeletion, see http://pserver.samba.org/cgi-bin/cvsweb/ppp/README.MPPE?annotate=1.4

When Micro$oft cobbled together PPTP, they used a compression feature of PPP to add encryption. But encryption makes the packets *grow*, not shrink. The network layer sometimes ends up with a packet which is larger than it is able to handle (*). Any packet which grows too large is dropped, and that plays havoc with the VPN.

RequestedDeletion, try reducing the MTU at the client end of the VPN and see if that makes a difference.

Regards

Charlie

(*) This is supposedly dealt with by the replacement ppp_generic.o module from the ppp-mppe-modules RPM (as mentioned in the README), but evidently it can't handle all client connections.

[guestHH]

I didn't want to report this question as a 'bug' for I didn't know what it ment exactly.

Thanks for the pointers.

Reducing the MTU value made the 'error' go away.
Still I can not get the server-manager. This a tcpdump of the ppp0 adapter of the server after establishing a vpn and trying to call the server manager:

18:27:00.387855 192.168.21.241.1803 > 192.168.21.1.http-admin: S 3341758178:3341758178(0) win 65280 (DF)
18:27:00.387950 192.168.21.1.http-admin > 192.168.21.241.1803: S 2026710826:2026710826(0) ack 3341758179 win 5424 (DF)
18:27:00.436360 192.168.21.241.1803 > 192.168.21.1.http-admin: . ack 1 win 65280 (DF)
18:27:00.481932 192.168.21.241.1803 > 192.168.21.1.http-admin: P 1:532(531) ack 1 win 65280 (DF)
18:27:00.482105 192.168.21.1.http-admin > 192.168.21.241.1803: . ack 532 win 6432 (DF)
18:27:01.367841 192.168.21.1.http-admin > 192.168.21.241.1803: P 1:203(202) ack 532 win 6432 (DF)
18:27:01.382818 192.168.21.1.http-admin > 192.168.21.241.1803: P 203:700(497) ack 532 win 6432 (DF)
18:27:01.498853 192.168.21.241.1803 > 192.168.21.1.http-admin: . ack 700 win 64581 (DF)
18:27:01.499152 192.168.21.1.http-admin > 192.168.21.241.1803: P 700:1714(1014) ack 532 win 6432 (DF)
18:27:01.529786 192.168.21.241.1804 > 192.168.21.1.http-admin: S 3342097290:3342097290(0) win 65280 (DF)
18:27:01.529867 192.168.21.1.http-admin > 192.168.21.241.1804: S 2039641415:2039641415(0) ack 3342097291 win 5424 (DF)
18:27:01.642920 192.168.21.241.1803 > 192.168.21.1.http-admin: P 532:1098(566) ack 1714 win 65280 (DF)
18:27:01.643103 192.168.21.241.1804 > 192.168.21.1.http-admin: . ack 1 win 65280 (DF)
18:27:01.643752 192.168.21.1.http-admin > 192.168.21.241.1803: . ack 1098 win 7358 (DF)
18:27:01.687018 192.168.21.241.1804 > 192.168.21.1.http-admin: P 1:558(557) ack 1 win 65280 (DF)
18:27:01.687258 192.168.21.1.http-admin > 192.168.21.241.1804: . ack 558 win 6127 (DF)
18:27:03.097493 192.168.21.1.http-admin > 192.168.21.241.1803: P 1714:1915(201) ack 1098 win 7358 (DF)
18:27:03.112486 192.168.21.1.http-admin > 192.168.21.241.1803: P 1915:2461(546) ack 1098 win 7358 (DF)
18:27:03.237045 192.168.21.241.1803 > 192.168.21.1.http-admin: . ack 2461 win 64533 (DF)
18:27:03.237348 192.168.21.1.http-admin > 192.168.21.241.1803: P 2461:3641(1180) ack 1098 win 7358 (DF)
18:27:03.419390 192.168.21.241.1803 > 192.168.21.1.http-admin: P 1098:1543(445) ack 3641 win 65280 (DF)
18:27:03.419645 192.168.21.1.http-admin > 192.168.21.241.1803: . ack 1543 win 8490 (DF)
18:27:03.420667 192.168.21.1.http-admin > 192.168.21.241.1803: . 3641:4997(1356) ack 1543 win 8490 (DF)
18:27:03.420877 192.168.21.1.http-admin > 192.168.21.241.1803: . 4997:6353(1356) ack 1543 win 8490 (DF)
18:27:03.421050 192.168.21.1.http-admin > 192.168.21.241.1803: . 6353:7709(1356) ack 1543 win 8490 (DF)
18:27:03.785953 192.168.21.1.http-admin > 192.168.21.241.1803: . 3641:4997(1356) ack 1543 win 8490 (DF)
18:27:04.525945 192.168.21.1.http-admin > 192.168.21.241.1803: . 3641:4997(1356) ack 1543 win 8490 (DF)
18:27:06.006018 192.168.21.1.http-admin > 192.168.21.241.1803: . 3641:4997(1356) ack 1543 win 8490 (DF)
18:27:07.098183 192.168.21.1.http-admin > 192.168.21.241.1804: P 1:243(242) ack 558 win 6127 (DF)
18:27:07.106943 192.168.21.1.http-admin > 192.168.21.241.1804: P 243:789(546) ack 558 win 6127 (DF)
18:27:07.237457 192.168.21.241.1804 > 192.168.21.1.http-admin: . ack 789 win 64492 (DF)
18:27:07.237755 192.168.21.1.http-admin > 192.168.21.241.1804: . 789:2145(1356) ack 558 win 6127 (DF)
18:27:07.237940 192.168.21.1.http-admin > 192.168.21.241.1804: . 2145:3501(1356) ack 558 win 6127 (DF)
18:27:07.238099 192.168.21.1.http-admin > 192.168.21.241.1804: . 3501:4857(1356) ack 558 win 6127 (DF)
18:27:07.655934 192.168.21.1.http-admin > 192.168.21.241.1804: . 789:2145(1356) ack 558 win 6127 (DF)
18:27:08.495941 192.168.21.1.http-admin > 192.168.21.241.1804: . 789:2145(1356) ack 558 win 6127 (DF)
18:27:08.965940 192.168.21.1.http-admin > 192.168.21.241.1803: . 3641:4997(1356) ack 1543 win 8490 (DF)
18:27:10.175971 192.168.21.1.http-admin > 192.168.21.241.1804: . 789:2145(1356) ack 558 win 6127 (DF)
18:27:13.535951 192.168.21.1.http-admin > 192.168.21.241.1804: . 789:2145(1356) ack 558 win 6127 (DF)
18:27:14.885950 192.168.21.1.http-admin > 192.168.21.241.1803: . 3641:4997(1356) ack 1543 win 8490 (DF)
18:27:20.255971 192.168.21.1.http-admin > 192.168.21.241.1804: . 789:2145(1356) ack 558 win 6127 (DF)

Thanks,
guestHH