#!/bin/bash

#
# recreate ssh host keys
#

sshdconfig="/etc/ssh/sshd_config"

if [ $(whoami) != "root" ]; then
    echo "you need to be root"
    exit 1
fi

if [ -r $sshdconfig ]; then
    while read line; do
        fletter=${line:0:1}
        if [ -z $fletter ]; then
            #empty line. skipping.
            :
        elif [ $fletter == "#" ]; then
            #comment. skipping.
            :
        else
            echo $line | grep "HostKey" >> /dev/null
            if [ $? -eq 0 ]; then
                file=$(echo $line | awk '{print $2}')
                if [ $file != "${file/_dsa_/}" ]; then
                    mv $file $file.old
                    mv $file.pub $file.pub.old
                    ssh-keygen -t dsa -f $file
                elif [ $file != "${file/_ecdsa_/}" ]; then
                    mv $file $file.old
                    mv $file.pub $file.pub.old
                    ssh-keygen -t ecdsa -f $file
                elif [ $file != "${file/_rsa_/}" ]; then
                    mv $file $file.old
                    mv $file.pub $file.pub.old
                    ssh-keygen -t rsa -f $file
                fi
            fi
        fi
    done < $sshdconfig
    exit 0
else
    echo "$sshdconfig - file not found"
    exit 1
fi