Server admins commonly use SSH to log in to Linux servers. They will disable login via password due to the ease of brute force attacks these days. The recommended practice is to only allow login to the servers using private/public keys. It is also good to set up SSH notifications with IP geolocation for better security. Admins will receive real-time notifications whenever anyone logs in to the servers.
Getting an immediate notification when someone logs in is beneficial from a security viewpoint. It increases the chance that you can prevent an authorized party from doing real damage to your server. If you see a login for a suspicious region or ISP, you can take remedial action ASAP. A fast response to intrusion will give the bad actor no chance to steal your data.
Pre-requisites to setup SSH notification with IP geolocation
Our script will use the Web Service to query geolocation data using the user’s IP address. WS4 has data about Country, Region, City and ISP; more than enough for our notification example. That said, you can use a different package if you require more geolocation data.
To use the Web Service, you need an API key. If you don’t have one, ip2 is an option:
https://www.ip2location.com/web-service/ip2location
In addition to the API key, you must also installjqandwgetin your Linux server. Thewgetpackage is required to call the Web Service while thejqpackage is required to parse JSON response from the web service.
SSH Login Notification Script
To enable the SSH notification script to run upon login, the following code should be copied and pasted into your~/.bashrcfile. ReplaceIP2LOCATION_API_KEYwith the actual Web Service API key.
If you want to enable Slack notification, then replaceSLACK_WEBHOOK_URLwith the actual URL. Otherwise, comment out the Slack-specific lines of codes.
Lastly, editNOTIFICATION_EMAILwith the email address that will receive the notification.
API_KEY="IP2LOCATION_API_KEY"
SLACK_WEBHOOK="SLACK_WEBHOOK_URL"
EMAIL="NOTIFICATION_EMAIL"
IP="$(echo $SSH_CONNECTION | cut -d " " -f 1)"
if [ ! -z "$IP" ]; then
RESULT="$(wget -q -O /dev/stdout 'https://api.ip2location.com/v2/?key='"$API_KEY"'&ip='"$IP"'&package=WS4')"
CITY="$(echo $RESULT | jq -r .city_name)"
REGION="$(echo $RESULT | jq -r .region_name)"
COUNTRY="$(echo $RESULT | jq -r .country_name)"
LOCATION="$(echo $CITY, $REGION, $COUNTRY | sed 's/^[, ]\+//g')"
ISP="$(echo $RESULT | jq -r .isp)"
HOSTNAME=$(hostname -f)
NOW=$(date +"%e %b %Y, %a %r (UTC %Z)")
# Slack notification
wget -q -O /dev/null --no-check-certificate --header 'Content-Type: application/json' --post-data '{"username":"'"$HOSTNAME"'", "icon_url":"https://i.imgur.com/X2W00e2.png", "channel":"#general", "attachments":[{"title":"SSH Notification", "color":"#FDAE02", "mrkdwn_in": ["text"], "text": "*IP Address*: '"$IP"'\n*Location:* '"$LOCATION"'\n*ISP:* '"$ISP"'\n*Date:* '"$NOW"'"}]}' $SLACK_WEBHOOK
# Email notification
echo "SSH login from $LOCATION ($IP)." | mail -s "SSH Login Notification" "$EMAIL"
fi
Conclusion: SSH Login Notifications with IP Geolocation
IP geolocation is useful to detect where your users are logging in from. If you see any locations that are in unexpected regions, you should be alert and perform a security audit of your system. A data breach is a very serious issue these days so it pays to be extra vigilant with your monitoring.