Friday, July 23, 2010

sshdo, an alternative to sudo

With sudo, you can execute any or custom command as the root user, optionally asking for your password. That poses some risk if someone knows your password (e.g. by logging/tapping).
But you could replace sudo with something that can login locally via other means like SSH. You need to use SSH(-agent) forwarding to pass down your identity so you won't have to type in any password. You then can decide with -A or -a option for ssh whether to enable or disable SSH forwarding (and thus root access).
It's not very fine grained though and it won't ask for a password each time you 'sshdo' but you could probably set something up with PAM settings (multi-factor). I'll look into that later.
Anyway, for root: /root/.ssh/authorized_keys should contain the allowed key. You'll want root access only locally and only via passwordless-authentication. For that, add to /etc/sshd_config

PermitRootLogin no
Match Address
        PermitRootLogin without-password

In your normal user directory, you can add an easy-to-use alias similar to sudo to ~/.bashrc or ~/.bash_profile

alias sshdo='ssh -q -t root@localhost -- cd $PWD \&\& sudo'

Test it and then disable sudo.
Hopefully this gives some good ideas.

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