If you have passwordless SSH configured on multiple servers, it’s a good idea to verify your access from time to time. This task may get rather tedious with a large number of remote systems. The simple script below will cycle through a list of servers and make sure you can access them without being prompted for a password. Any failures will be saved in the CSV file for later analysis.

#!/bin/bash
#                                      |
#                                  ___/"___
#                          __________/ o __________
#                            (I) (G) ___/ (O) (R)
#                                 2013-09-19
# ----------------------------------------------------------------------------
# Verify passwordless access to servers in the list (see $infile variable)
# The list must contain one server name per line
# ----------------------------------------------------------------------------
#
infile=""

spinner()
{
    local pid=$1
    local delay=0.25
    local spinstr='|/-'
    while [ "$(ps a | awk '{print $1}' | grep $pid)" ]; do
        local temp=${spinstr#?}
        printf " [%c]  " "$spinstr"
        local spinstr=$temp${spinstr%"$temp"}
        sleep $delay
        printf "bbbbbb"
    done
    printf "    bbbb"
}

configure() {
	timestamp=$(date +'%Y-%m-%d %H:%M:%S')
	if [ -z "${infile}" ]
	then
		infile="/tmp/unix_master_list.txt"
	fi

	if [ ! -r "${infile}" ]
	then
		echo "Server list ${infile} not found. Exiting..."
		exit 1
	fi

	outfile=${HOME}/server_list_checker.csv
	if [ -f "${outfile}" ]
	then
		/bin/rm -f "${outfile}"
		echo "Date,Hostname,Error" >> "${outfile}"
	fi

	ssh_command="/usr/bin/ssh -qt -o PubkeyAuthentication=yes -o PasswordAuthentication=no -o StrictHostKeyChecking=no -o ConnectTimeout=10 -o NumberOfPasswordPrompts=0"
	server_total=$(wc -l "${infile}" | awk '{print $1}')
}

check_access() {
	i=1
	for host in `cat "${infile}" | egrep -v "-vip|-ilo"`
	do
			status_ping=1 ; status_ssh=1
			status_ping=$(/bin/ping -q -c 2 -i 1 -W 1 -w 2 ${host} > /dev/null 2>&1 ; echo $?)
			if [ ${status_ping} -eq 0 ]
			then
					status_ssh=$(${ssh_command} username@${host} "uptime" > /dev/null 2>&1 ; echo $?)
					if [ ${status_ssh} -ne 0 ]
					then
							echo "${timestamp},${host},ssh failure" | tee -a "${outfile}"
					fi
			else
					echo "${timestamp},${host},ping failure" | tee -a "${outfile}"
			fi
			clear
	cat << EOF
Failures so far:
----------------------------------------------

`cat "${outfile}"`
----------------------------------------------

Checking host ${i} of ${server_total}: ${host}
EOF
			(( i = i + 1 ))
	done
}

# RUNTIME
configure
check_access & spinner $!