[plug] Refresh ssh keys

[Leon Brooks]

On Monday 25 November 2002 08:11 pm, J Michael Gilks wrote:
> However, ssh will not work to any machines on the network. Bang go my
> dreams of a monitorless server quietly chugging in the background, being
> administered by webmin and ssh from the internal network.

> Reading man pages for ssh, ssh-add and etc has left me fairly confused and
> in need of assistance.

> The keys ssh uses seem to be stored in $HOME for each user on the computer.

> Can I refresh the keys for all users, or does each user need to refresh
> their own key, and how do they do it.

Generally, users delete defunct keys and add their own new ones in 
~/.ssh/known_hosts. If you have a significant machine which has changed, you 
could scrub the defunct key with something like this:

OLDK="stringofhexrubbish"
NEWK="differentstringofrubbish"
for user in $(gawk -F: </etc/passwd '$3 > 100 { print $1 }'); do
    cd $(gawk -F: </etc/passwd "\$1 == $user { print $6 }')/.ssh
    if [ -f known_hosts ]; then
        rm -f kh.temp
        touch kh.temp
        chown $user kh.temp
        chmod 600 kh.tmp
        grep -v "$OLDK" < known_hosts >> kh.temp
        echo name.of.host $NEWK >> kh.temp
        echo ip.of.ho.st $NEWK >> kh.temp
        mv -f kh.temp known_hosts
    fi
done

There will, of course, be a neater PERL solution... listen for the quiet 
crinkle of green fees being paid. (-:

Cheers; Leon