Remote network restart

I guess anyone who's administered several remote boxes has had the unfortunate problem of (when not thinking straight) taking down the network card on a machine you have no physical access to. The result being that the ssh session you used to connect dies. The typical mistake is to do something like (as root):

ifconfig eth0 down; ifconfig eth0 inet 123.4.5.6; ifconfig eth0 up

The unfortunate result being that the first statement disconnects your session and hangs up the chain resulting in the network not coming back up. A nice way around this is to use the bash "disown" builtin command, ie:

(sleep 5; ifconfig eth0 inet 123.4.5.6; ifconfig eth0 up)& disown -h $! ; ifconfig eth0 down

In this case you launch a backgrounded task that is disconneced from the session (meaning the ssh session dying won't kill the process) which sleeps for 5 seconds (to give the down a chance to happen) then configures the network card as appropriate and brings it back up. As soon as this launches and is disowned, then immediately takes the network card down. If the configuration change keeps the IP address the same, you'll find that after 5 seconds your bash prompt just comes back and the session resumes.

Shutdown a windows PC from linux

A remote Windows PC can easily be shutdown, assuming you have Samba installed on your Linux box, and you have a user account on the Windows PC that has the necessary rights.

Just enter the following command, where 'thehostname' is the hostname of the remote PC, and 'theusername' is a valid user account on the remote PC:

net rpc shutdown -S thehostname -U theusername

If the hostname is not known, or cannot be resolved, then use the following instead, replacing '111.111.111.111' with the IP address of the remote PC:

net rpc shutdown -I 111.111.111.111 -U theusername

Additionally, the parameters that can be used with Windows' own shutdown command such as '-f' to force or '-t' to set a timeout, can also be applied to the net rpc shutdown command as well. For example the following will wait 60 seconds, and then force all running programs to terminate before shutting down:

net rpc shutdown -S thehostname -U theusername -f -t 60

Remote Window Managers

Lots of times it’s extremely frustrating or time consuming to run an xterm on a remote host just to fork your programs from that remote machine. Why not just run your window manager there even though you’re not on its console? The window manager is just another X application, after all, isn’t it?

Fire off your local X server

xinit /usr/bin/xterm — :1 &

yields a vanilla X session with merely an xterm running - no window manager. Now you need to add permissions to this window session for the remote host. You can tunnel the connection through SSH if your network is insecure but there’s a distinct performance hit. If your network is secure, you can just “xhost +remotehost” and spray directly to your X server:

Tunneled SSH:

ssh -fY remotehost /usr/bin/wmaker

or spray directly:

xhost +remotehost
ssh -f remotehost /usr/bin/wmaker -display localmachine:1

The first option, if your remote SSH server supports it, will use a locally defined DISPLAY that then gets tunneled to your local side over SSH. The second option allows remotehost to send X data directly to your local display, then runs WindowMaker there but displaying it locally. Now all your desktop actions are done on the remote machine, not locally.