[pptp-server] ppp_mppe.o: kernel-module version mismatch

[Cowles, Steve]

Are you sure you "installed" the modules (or even the kernel) after you
compiled your kernel/modules?

On my Poptop server (RH6.1), I basically had to perform the following steps
to get everything to play together.

1) make config  or  make xconfig

Make sure the following options were set by viewing the
/usr/src/linux/.config file after running the above.
CONFIG_MODULES=y
CONFIG_MODVERSIONS=y
CONFIG_KMOD=y

2) make bzImage

This will compile the kernel only, not the modules.

3) make modules

This will compile the modules designated during step one above.

4) make modules_install

This will copy the modules created in step three above to (typically) 
/lib/modules/<kernel-rev>/<sub-dir> With regards to ppp_mppe.o, sub-dir=net

5) Copy the compiled kernel image to (typically) /boot. On my system, I use
cp /usr/src/linux/arch/i386/boot/bzImage /boot/vmlinuz

FYI: An excellent resource that I use for my Redhat system on
compiling/installing/upgrading the kernel is
http://www.redhat.com/support/docs/howto/kernel-upgrade/kernel-upgrade.html

6 lilo -v

Update the master boot record

7) If you want the kernel to suppress those annoying syslog messages about
"unable to locate..." crap, then you will also need to edit
/etc/conf.modules and make sure it contains the following:

alias ppp-compress-18 ppp_mppe
alias ppp-compress-21 bsd_comp
alias ppp-compress-24 ppp_deflate
alias ppp-compress-26 ppp_deflate
alias tty-ldisc-3     ppp_async
alias tty-ldisc-14    ppp_synctty
alias char-major-108  ppp_generic

6) reboot

If all is well and the module dependencies are correct (depmod), when you
try to connect from a PPTP client, you should NOT have to load any modules
manually. i.e. no insmod. 

To illustrate:

Loaded modules before initiating a PPTP connection from my W2K system
[scowles at voyager boot]$ lsmod
Module                  Size  Used by
3c59x                  19496   1  (autoclean)

Loaded modules after initiating a PPTP connection from my W2K system.
[scowles at voyager boot]$ lsmod
Module                  Size  Used by
ppp_deflate            40536   0  (autoclean)
ppp_mppe               13572   2  (autoclean)
bsd_comp                3620   0  (autoclean)
3c59x                  19496   1  (autoclean)

and the corresponding syslog output
Sep  1 11:14:42 voyager kernel: registered device ppp0
Sep  1 11:14:42 voyager pppd[14635]: pppd 2.3.11 started by root, uid 0
Sep  1 11:14:42 voyager pppd[14635]: Using interface ppp0
Sep  1 11:14:42 voyager pppd[14635]: Connect: ppp0 <--> /dev/pts/3
Sep  1 11:14:44 voyager pptpd[14634]: CTRL: Ignored a SET LINK INFO packet
with real ACCMs!

Sep  1 11:14:45 voyager kernel: PPP BSD Compression module registered
Sep  1 11:14:45 voyager kernel: PPP MPPE compression module registered
Sep  1 11:14:45 voyager kernel: PPP Deflate Compression module registered

Sep  1 11:14:45 voyager pppd[14635]: MSCHAP-v2 peer authentication succeeded
for COWLES\\scowles
Sep  1 11:14:45 voyager pppd[14635]: found interface eth0 for proxy arp
Sep  1 11:14:45 voyager pppd[14635]: local  IP address 192.168.9.4
Sep  1 11:14:45 voyager pppd[14635]: remote IP address 192.168.9.100
Sep  1 11:14:52 voyager pppd[14635]: MPPE 128 bit, stateless compression
enabled

Notice that the kernel has taken care of auto loading these modules based on
their dependencies. It will also "remove" these modules (automatically) when
they are not in use after some inactivity timeout period.

For example, about 10 minutes after I disconnected my W2K system from my
PopTop server, my syslog output generated the following:

Sep  1 11:30:00 voyager kernel: PPP MPPE compression module unregistered

[scowles at voyager net]$ lsmod
Module                  Size  Used by
3c59x                  19496   1  (autoclean)

Hope this helps.
Steve Cowles


> -----Original Message-----
> From: Jean-Paul Chavant [mailto:chavant at geosys.fr]
> Sent: Friday, September 01, 2000 8:31 AM
> To: Pptp
> Subject: [pptp-server] ppp_mppe.o: kernel-module version mismatch
> 
> 
> Hello,
> 
> my VPN box is a Bi-processor mother board under linux 2.2.14-15mdksmp.
> 
> my first problem was "can't locate module ppp-mppe". So in the FAQ to
> resolve the problem, i have to do :
> 
> >yeah, in your /lib/modules/<kernel version>/net/ directory, 
> there should
> >be files called bsd_comp.o and ppp_deflate.o.. insmod those files and
> >you'll be good to go.
> 
> i 'll do that but now i got another error :
> 
> [root at endeavour net]# insmod ppp_mppe
> ./ppp_mppe.o: kernel-module version mismatch
>         ./ppp_mppe.o was compiled for kernel version 2.2.14-15mdk
>         while this kernel is version 2.2.14-15mdksmp.
> 
> How can i resolve this problem ?
> 
> thanks.
> 
> JPaul
> 
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