Network Monitoring Bash Scripts

In order to monitor my home broadband internet connection, I set up my Raspberry Pi (Model B+) with some simple scripts to capture net work logs

• Speed test - for download and upload speed
• Ping test - for ping times and packet loss

System Configuration

Hardware and OS setup

• Raspberry Pi Model B+ - should work for any Raspberry Pi.
• Raspbian GNU/Linux 8 (jessie) 4.4.21+ #911 Thu Sep 15 14:17:52 BST 2016
• Initially set up your Pi using a keyboard and screen - but if you configure SSH you won't need them after the initial config.
• Connect the Pi directly to the broadband router by an Ethernet cable - do not use WiFi, speed tests can be limited by your WiFi speed and won't be accurate.

Software setup

• Before you begin, make a note of the Pi's IP address in order to connect via SSH later, $ ifconfig eth0.
• Enable the SSH server on the Pi:
  1. On the command line $ sudo raspi-config
  2. Select Advanced options
  3. Select SSH
  4. In the dialog 'Would you like to enable the SSH server' - select Yes
  5. Back in the main menu, select Finish
  6. Reboot for changes to take effect $sudo shutdown -r now
• Use an SSH client to connect remotely to the Pi, I like PuTTY
• Install Speedtest-cli - this is a command line speedtest app written in Python, it works in the same way as the speedtest.net website. To install it:
  1. sudo apt-get install python-pip
  2. sudo pip install speedtest-cli

Scripts

• speedtest.sh - This runs the speedtest-cli Python script and stores the output in a filename with a date and time stamp e.g. speedtest.161205-1530, results are stored in ~/results/.
• pingtest.sh - Like the previous shell script, this runs a ping command against the Google DNS server address (8.8.8.8) for a count of 60 i.e. an ICMP ping packet every second for 60-seconds. Again, results are stored in a file with the date and time stamp in the name e.g. pingtest.161205-1551. These are also saved to the ~/results/ directory.
• collate_speed.py - collates all the speedtest download and upload results into a Comma Separated Value (CSV) format summary - the resulting file can then be easily imported into a spreadsheet for analysis or graphs.
• collate_ping.py - collates ping test results into two CSV files, one for just the packet loss statistics and one for all the other ping stats.

Run scripts as a cron job

1. Edit the system cron jobs using the command $ crontab -e
2. This is an example of how I configured it:

# Edit this file to introduce tasks to be run by cron.
# 
# Each task to run has to be defined through a single line indicating with different fields when the task will be run and what command to run for the task
# 
# To define the time you can provide concrete values for minute (m), hour (h), day of month (dom), month (mon), and day of week (dow) or use '*' in these fields 
# (for 'any').# Notice that tasks will be started based on the cron's system daemon's notion of time and timezones.
# 
# Output of the crontab jobs (including errors) is sent through email to the user the crontab file belongs to (unless redirected).
# 
# For example, you can run a backup of all your user accounts at 5 a.m every week with: 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
# 
# For more information see the manual pages of crontab(5) and cron(8)
# 
# m h dom mon dow command
*/10 * * * 2 /home/pi/cookbook/net-mon/pingtest.sh && /home/pi/cookbook/net-mon/speedtest.sh

With this configuration, the ping test is run every 10-minutes and the speedtest is run after it finishes. The tests only run on a Tuesday (day 2 in Days Of Week (dow)), in my setup.