I have some troubles with my server! After I asked for support, I get the following answer:
You can use the serial port to reset your network configuration.
I have a client machine with Ubuntu Oneiric Ocelot (11.10) installed on it and a cable for serial access with 9 pins in a head and a network connector in the other. Can anyone give me some hints on how can I access my server via serial port?
Best Answer
Even though it's not access via serial port, you could probably solve your problem by connecting a monitor and keyboard physically to your server, then reboot into single-user mode. In this mode, you get root access without a password, and you could reset your user/password.
For single user boot, see: http://centos.org/docs/5/html/5.1/Installation_Guide/s1-rescuemode-booting-single.html