[root@host boot]# openvpn --config /etc/openvpn/server.conf  --mktun
Thu Jan 24 09:42:40 2008 Note: Cannot open TUN/TAP dev /dev/net/tun: No such file or directory (errno=2)
Thu Jan 24 09:42:40 2008 Note: Attempting fallback to kernel 2.2 TUN/TAP interface
Thu Jan 24 09:42:40 2008 Cannot allocate TUN/TAP dev dynamically
Thu Jan 24 09:42:40 2008 Exiting

пробуем по другому:
[root@host boot]# openvpn --config /etc/openvpn/server.conf
Thu Jan 24 09:44:25 2008 OpenVPN 2.0.9 i686-pc-linux [SSL] [LZO] [EPOLL] built on Jan 24 2008
Thu Jan 24 09:44:25 2008 Diffie-Hellman initialized with 1024 bit key
Thu Jan 24 09:44:25 2008 TLS-Auth MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Thu Jan 24 09:44:25 2008 Note: Cannot open TUN/TAP dev /dev/net/tun: No such file or directory (errno=2)
Thu Jan 24 09:44:25 2008 Note: Attempting fallback to kernel 2.2 TUN/TAP interface
Thu Jan 24 09:44:25 2008 Cannot allocate TUN/TAP dev dynamically
Thu Jan 24 09:44:25 2008 Exiting

[root@host boot]# ls -al /dev/net/tun
ls: /dev/net/tun: No such file or directory

[root@host modules]# modprobe tun
FATAL: Could not load /lib/modules/2.6.9-023stab044.4-enterprise/modules.dep: No such file or directory
[root@host modules]# uname -a
Linux host 2.6.9-023stab044.4-enterprise #1 SMP Thu May 24 17:41:23 MSD 2007 i686 athlon i386 GNU/Linux
[root@host modules]#

[root@host modules]# ls -al /lib/modules/
total 9
drwxr-xr-x   6 root root 1024 Jan 24 09:45 .
drwxr-xr-x  12 root root 4096 Jan 24 09:19 ..
drwxr-xr-x   3 root root 1024 Jan 24 06:38 2.6.9-67.0.1.EL
drwxr-xr-x   2 root root 1024 Jan 24 09:08 2.6.9-67.0.1.ELhugemem
drwxr-xr-x   2 root root 1024 Jan 24 09:07 2.6.9-67.0.1.ELsmp
drwxr-xr-x   2 root root 1024 Dec 19 15:58 kabi-4.0-0

обычно у меня все гладко..
что зделать что бы этот tun появился :)

• openvpn не стартует. centos-4.5,DogEater, 15:27 , 25-Янв-08

rtfm

TUN/TAP Driver Configuration:

* Linux 2.4 or higher (with integrated TUN/TAP driver):

  (1)  make device node:         mknod /dev/net/tun c 10 200
  (2a) add to /etc/modules.conf: alias char-major-10-200 tun
  (2b) load driver:              modprobe tun
  (3)  enable routing:           echo 1 > /proc/sys/net/ipv4/ip_forward

  Note that either of steps (2a) or (2b) is sufficient.  While (2a)
  only needs to be done once per install, (2b) needs to be done once
  per reboot.  If you install from RPM (see above) and use the
  openvpn.init script, these steps are taken care of for you.

http://openvpn.net/install.html