Print table of all sshd HostKeys

ssh_fprint.sh

#!/bin/bash
# server_ssh_fingerprints
# Extracted from: https://superuser.com/questions/929566/sha256-ssh-fingerprint-given-by-the-client-but-only-md5-fingerprint-known-for-se
#
# Version 0.3
#
# 2016 Kepi <[email protected]
# MIT License
#
# Print fingerprint matrix for all allowed Host Keys
# with all allowed ciphers and MD5 and SHA-256 algos
#
# Changelog:
#
# 2018-03-11 (0.2):
# - Support for newer versions of OpenSSH
# - Added visual keys for all algos too - only in recent OpenSSH versions
# 2018-05-27 (0.3-webash):
# - Removed superfluous table lines
# - Added cipher bit depth
# - Rerranged so that most important information is first
# - Removed 'md5:'/'sha:' from some outputs

# standard sshd config path
SSHD_CONFIG=/etc/ssh/sshd_config

# helper functions
function tablize {
    awk '{printf("%-7s %-48s %-4s %-7s \n", $1, $2, $3, $4)}'
}
# LINE=" +---------+---------+-----------------------------------------------------+"

# header
# echo "$LINE"
# echo "Cipher" "Algo" "Fingerprint" | tablize
# echo "$LINE"

declare -A ALGOS
declare -a ASCII

# fingerprints
while read -r host_key; do
    cipher=$(echo "$host_key" | sed -r 's/^.*ssh_host_([^_]+)_key\.pub$/\1/'| tr 'a-z' 'A-Z')
    if [[ -f "$host_key" ]]; then
	bitdepth=$(ssh-keygen -l -f $host_key | awk '{print $1}')
		
        if ssh-keygen -E md5 -l -f "$host_key" &>/dev/null; then
		IFS=$'\n'

		for algo in md5 sha256; do
		    n=0
		    for line in $(ssh-keygen -E $algo -lv -f "$host_key"); do
			n=$(( n + 1))
			if [[ $n -eq 1 ]]; then
			    ALGOS[$algo]=$(echo "$line" | awk '{sub(/(MD5:|SHA256:)/,"");print $2}')
			else
			    ASCII[$n]="${ASCII[$n]} ${line}"
			fi
		    done
		done
        else
            ALGOS[md5]=$(ssh-keygen -l -f "$host_key" | awk '{print $2}')
            ALGOS[sha256]=$(awk '{print $2}' "$host_key" | base64 -d | sha256sum -b | awk '{print $1}' | xxd -r -p | base64)
        fi

        echo "$cipher" "${ALGOS[md5]}" "$bitdepth" MD5 | tablize
        echo "$cipher" "${ALGOS[sha256]}" "$bitdepth" SHA-256 | tablize
        #echo "$LINE"
    fi
 done < <(awk '/^HostKey/ {sub(/^HostKey\s+/,"");print $0".pub"};' $SSHD_CONFIG)

echo
for line in "${ASCII[@]}"; do
    echo "$line"
done