print-remote-cert

#!/bin/bash

# Take a domain and print the certificate information at that domain;
# this does not verify if the domain or port number are valid. If the
# script hangs or times out, there may be a connection problem; check
# that the hostname and port are reachable.

display_usage() {
  echo "Usage: $(basename ${0}) hostname [port]"
  echo ""
  echo "hostname   host/domain name to check"
  echo "port       port number; defaults to 443"
  echo ""
  exit 1
}

# Check if no arguments have been passed
if [ $# -eq 0 ]; then
  display_usage
fi

# Default port to 443
if [ -z "$2" ]; then
  port="443"
else
  port="$2"
fi

hostname="$1"
host_port="${hostname}:${port}"

echo | openssl s_client -showcerts -servername "${host_port}" -connect "${host_port}" 2>/dev/null | openssl x509 -inform pem -noout -text