get-certificate

#!/bin/bash

# Connect to a remote SSL-capable server and extract its certificate

set -o pipefail

hostname=${1}
port=${2:-443}

if [ "!${hostname}!" == "!!" ]; then
    echo "Usage: ${0} <hostname> [<port>]" >&2
    exit 255
fi

response=$(echo | openssl s_client -connect "${hostname}":"${port}" -servername "${hostname}" 2>&1)
rc=$?
if [ ${rc} -ne 0 ]; then
    echo "${response}" >&2
    exit ${rc}
fi

echo "${response}" | sed -n '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p'