Here’s how to find if clients are connected to Apache or Nginx service.
netstat -tn src: 80 netstat -tn src: 443 |
connection
Internet Test
My internet has been flaky lately. I wrote a script that logs my internet connection.
I’m running it in cron every minute.
#!/bin/bash log='/home/ulysses/Code/spectrum.log' if nc -zw1 google.com 443; then echo 'Spectrum is up' $(date) >> $log else echo 'Spectrum is down' $(date) >> $log fi |
To view, just cat the log.
cat spectrum.log Spectrum is up Fri Jun 26 15:14:01 EDT 2020 Spectrum is up Fri Jun 26 15:15:01 EDT 2020 Spectrum is up Fri Jun 26 15:16:01 EDT 2020 Spectrum is up Fri Jun 26 15:17:01 EDT 2020 Spectrum is up Fri Jun 26 15:18:01 EDT 2020 |
So, I now have a record when it was up or down.
Testing a Network Port Connection
You can test a network port connection using the “nc” command on Linux and “telnet” on Windows.
Format:
$ nc -zv domain.com port
C:\> telnet domain.com port
$ nc -zv domain.com 80 Connection to domain.com 80 port [tcp/http] succeeded! |
C:\> telnet -zv domain.com 80 Connecting To domain.com...Could not open connection to the host, on port 80: Connect failed |
For Telnet, if a connection is successful, it returns no message.
Check DB Connection on AWS
When setting up your cloud infrastructure, you can check if your instances have access to the database by performing this command.
$ nc -zv 10.0.0.45 3306 $ nc -zv domain.com 3306 $ nc -zv endpoint.amazonaws.com 3306 |
If connection has succeeded, you’ll get a message like this in Linux and MacOS …
Connection to endpoint.amazonaws.com 3306 port [tcp/mysql] succeeded! |
On Windows, you can use Telnet to test your DB connection.
C:\>telnet endpoint.amazonaws.com 3306 |
If connection has succeeded, the result is “no message.” If there’s a problem, you’ll get this ….
Connecting To endpoint.amazonaws.com...Could not open
connection to the host, on port 3306: Connect failed |