PPP in container

Our goal is to start the pppd daemon in a virtual machine. Then it is possible, for example, to connect to your DSL provider in a VM.

Caveat

It is necessary to run one of these 3 kernels :

• rhel6
• 2.6.27 briullov.1 or later
• rhel5 064.4 or later

One other thing. I am not 100% sure about this but I think both the host and the container need to be running the same bit version OS. So both need to be 32bit or 64bit. That is what I found the one time I tried this running a 32bit container on a 64bit host.

Howto

• ppp modules need to be loaded in the HN :

HN # modprobe ppp_async
HN # modprobe ppp_deflate
HN # modprobe ppp_mppe
HN # lsmod | grep ppp
ppp_mppe                6420  2
ppp_deflate             9793  2
zlib_deflate           21977  1 ppp_deflate
ppp_async              15169  1
crc_ccitt               6337  1 ppp_async
ppp_generic            30165  6 ppp_deflate,ppp_async
slhc                   10561  1 ppp_generic

• to make these HN changes persistent on reboot create a file called ppp.modules. You can use any name you like but you must give it a .modules extension. The following method and directory location is applicable to CentOS v6. I am not sure about v5. The directory location may be different for that version.

HN # nano /etc/sysconfig/modules/ppp.modules

#!/bin/sh
/sbin/modprobe ppp_async
/sbin/modprobe ppp_deflate
/sbin/modprobe ppp_mppe

HN # chmod +x /etc/sysconfig/modules/ppp.modules

• set "ppp" feature for stoppped VE:

HN # vzctl set [VEnumber] --features ppp:on --save

• start VE :

HN # vzctl start [VEnumber]

• Prepare /dev/ppp within VE:

HN # vzctl set [VEnumber] --devices c:108:0:rw --save
HN # vzctl exec [VEnumber] mknod /dev/ppp c 108 0
HN # vzctl exec [VEnumber] chmod 600 /dev/ppp

• See if it works (as root):

VE# /usr/sbin/pppd

You should see gibberish in the standard output like

~�}#�!}!}!} }4}"}&} } } } }%}&)Q�}4}'}"}(}"p})

This will go on for about 30 seconds and then you will be returned to a command prompt. If there is an error message instead, something went wrong.

• From that point, you can finish your setup as in a real hardware environment.

See also

• A complete test case for ppp virtualization : one VM as a client, one VM as a server. http://268.bugzilla.openvz.org/attachment.cgi?id=512
• The feature request and discussion in bugzilla : http://bugzilla.openvz.org/show_bug.cgi?id=268