firefox proxy

If your web browsing is restricted you can use a remote server to get round it. In the firefox network settings choose manual proxy and a port number. Then at the command line type:

> ssh -XfN -D PORT -p 22 user@server

Now when you surf the packets will be redirected through this ssh tunnel.

Password protect grub

By default with Ubuntu the user can use grub to login with root privileges WITHOUT a password, which I don't feel comfortable with. This is how I password protected grub to prevent changing the boot process:

> grub
grub> md5crypt

Password: YOUR_PASSWORD
Encrypted: abcdef

grub> quit


Now copy the encrypted string into the start of the grub file:

> sudo vim /boot/grub/menu.lst
password --md5 abcdef
lock

After saving change the permissions to prevent other uses viewing the file:
> sudo chmod 600 /boot/grub/menu.lst

Recover password

If you forget your login password it can be recovered through grub. At boot enter the grub menu and choose 'single'. This will get you a root command prompt. Now run 'passwd' to set a new password. Now anyone can do this if they get access to your machine so you should password protect grub. I will write how to do this later.

Email from the command line

echo "message" | mutt -s "subject" -x address@host.com

Passwordless ssh

It becomes a hassle hopping between servers with ssh if you have to type the password each time. To enable passwordless ssh go:

> ssh-keygen -t dsa (ENTER to skip password)
> scp ~/.ssh/id_dsa.pub user@other_server

And on the other server:
> cat ~/id_dsa.pub >> ~/.ssh/authorized_keys
> rm ~/id_dsa.pub

Now you can hop between servers without a password. I only do this for servers that I can afford to be compromised.

Extracting tar balls

I always forget the flags:

tar -xvvf file.tar
tar -xvvzf file.tar.gz
tar -zxvf file.tgz
tar xjvf file.tar.bz2

Moving and svn repository

To move an svn repository first dump it to a file with:

> svnadmin dump /path/to/repository > svn.dump

Now to create the new repository go:

> svnadmin create new_repository_name
> svnadmin load new_repository_name < svn.dump