[Solved] MPPE Support

Fill · 08-21-2011, 08:59 AM

Hi,

I'm trying to set up a PPTP server, using pptpd (aka poptop).

Everything seemed to be going fine untill I tried to connect a windows client to the server, and I got an error saying that MPPE is required, but kernel doesn't support it.

After some googling, if I understood it well, recent kernels are supposed to have native MPPE support. Am I right?

The server is running debian and kernel compiled by me with grsecurity:

Code:

filipe@BOX4:~$ cat /etc/debian_version
5.0.8
filipe@BOX4:~$ uname -a
Linux BOX4 2.6.32.43-grsec #1 SMP Tue Aug 9 14:02:16 WEST 2011 i686 GNU/Linux

I also see that there are no modules loaded (or available) related to ppp, mppe, etc.:

Code:

BOX4:/home/filipe# lsmod | grep mppe
BOX4:/home/filipe# modprobe -l | grep mppe
BOX4:/home/filipe#

Still, I tried to load ppp_mppe, with no luck (I get no such module error).

Can anyone point me in the right direction please?

Thanks in advance,
Fill

Fill · 08-21-2011, 02:42 PM

Hey there,

I tried to recompile my kernel using all PPP related options enabled (under Device Drivers -> Network supporting).

I still get the same errors in syslog:

Code:

BOX4:/var/log# tail syslog
Aug 21 20:28:09 BOX4 pptpd[2716]: CTRL: Ignored a SET LINK INFO packet with real ACCMs!
Aug 21 20:28:10 BOX4 pppd[2717]: MPPE required, but kernel has no support.
Aug 21 20:28:10 BOX4 pppd[2717]: Connection terminated.
Aug 21 20:28:10 BOX4 pptpd[2716]: CTRL: Reaping child PPP[2717]
Aug 21 20:28:10 BOX4 pppd[2717]: Connect time 0.1 minutes.
Aug 21 20:28:10 BOX4 pppd[2717]: Sent 0 bytes, received 0 bytes.
Aug 21 20:28:10 BOX4 pppd[2717]: tcflush failed: Input/output error
Aug 21 20:28:10 BOX4 pppd[2717]: Exit.
Aug 21 20:28:10 BOX4 pptpd[2716]: CTRL: Client 84.***** control connection finished
Aug 21 20:28:15 BOX4 pptpd[2715]: MGR: dropped small initial connection
BOX4:/var/log#

I don't know what else can I do... grr

Fill · 08-22-2011, 04:49 AM

OK.. I see that I have the source files in kernel, but I just can't figure where in make menuconfig I can select it to get them compiled and working...

BOX4:/home/filipe# find / -name *mppe*
/usr/src/linux-2.6.32.43/drivers/net/ppp_mppe.c
/usr/src/linux-2.6.32.43/drivers/net/ppp_mppe.h

I thought it was under Device Drivers -> Networking support, but nothing...

Fill · 08-22-2011, 09:25 AM

SOLVED!!! Finally

According to this website - http://cateee.net/lkddb/web-lkddb/PPP_MPPE.html - CONFIG_PPP_MPPE depends on CONFIG_EXPERIMENTAL. I had compiled my kernel without CONFIG_EXPERIMENTAL, so I didn't have MPPE option available in make menuconfig.

This is, in fact, easy to fix, as I just needed to enable "Prompt for development and/or incomplete code/drivers" inside General Setup.

After that I could select "PPP MPPE compression (encryption)" inside "PPP support menu" (under Device Drivers -> Network device support. I also had to compile kernel with PPP filtering, because PPTP was complaining that ppp filtering wasn't supported by my current kernel.

This was tricky .. I hope it will help someone in future.

Cheers,
Fill