Hey there...I've searched, and I've tried rolling various kernels (besides the default they won't work for me...but oh well), and different distros but still nada luck on trying to get MPPE working with any sorta kernel any sorta way.

There've been a few topics about this already...about half a decade old...=D
archive/o_t/t_1188/mppe_support.html
viewtopic.php?t=1567&view=next

Any chance we could get MPPE usable in a kernel soon?

Thanks!

Seems to be in there with recent builds, at least:

rtucker@framboise:~$ uname -a
Linux framboise 2.6.39.1-linode34 #1 SMP Tue Jun 21 10:29:24 EDT 2011 i686 GNU/Linux
rtucker@framboise:~$ zgrep MPPE /proc/config.gz 
CONFIG_PPP_MPPE=y

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Hmm, yeah it seems to be in my kernel package too but does it matter if it doesn't respond from a modprobe?

[root@li180-179 ~]# zgrep MPPE /proc/config.gz
CONFIG_PPP_MPPE=y
[root@li180-179 ~]# modprobe ppp-compress-18 && echo ok
FATAL: Module ppp_mppe not found.

Well, guess I'll try to compile pptpd and see if it works...

modprobe is for modules (e.g, not statically compiled into the kernel). It expects to find the module in /lib/modules/`uname -r`, which should be empty for Linode kernels, which all use entirely compiled-in features. So modprobe failing in this case is expected behavior. Checking /proc/config.gz is the simplest way to check for a feature in a Linode kernel.

If you do find yourself needing features (whether static or module) not included in a Linode kernel you'll need to build your own kernel and use the pv-grub approach.

Oh, and it looks like the ppp-compress module name is normally aliased to either bsd_comp or ppp_deflate, both of which also appear to be included in Linode's kernels.

-- David