How to Troubleshoot Common Issues with Debian Free Web Servers

Debian is the world’s most popular Linux distribution, thanks in part to their wide range of free software options. Running web servers on Debian systems, however, can present some unique challenges. In this blog post, I’m going to discuss some of the most common issues and how to fix them.

Troubleshooting Abnormal CPU/Memory Usage

A major challenge when running web servers on Debian is managing CPU and memory usage. If your website or application is abnormally using too much system resources, chances are something isn’t quite right. The best way to troubleshoot this issue is to identify the source of the problem. The first step is to generate a process tree with the Linux `ps` command to determine which processes are running. For example:

# ps -A
  PID TTY          TIME CMD
    1 ?        00:00:06 init
    2 ?        00:00:00 kthreadd
    3 ?        00:00:00 ksoftirqd/0
    .
    .
   220 ?        00:00:01 mysqld
   232 ?        00:00:00 apache2
   .
   .
  254 ?        00:00:00 sshd
  492 ?        00:00:00 httpd
  493 ?        00:00:00 httpd
  .
  .

In the example above, the `mysqld` and `apache2` processes are hoarding the most system resources. You can then use the `top` command to view the memory usage of each process. To exit out of `top`, use the `Ctrl+C` shortcut combination.

Troubleshooting Apache Issues

If you’re running the Apache web server on Debian, there are some common issues you may encounter. For example, you may be experiencing high latency when loading web pages. In this case, the issue more than likely lies within Apache’s configuration file. The best way to troubleshoot this is to access the Apache configuration file located at `/etc/apache2/apache2.conf`.

Inside the configuration file, pay close attention to the server settings and the amount of threads running. If the configuration is not suitable to the system and the amount of threads are higher than they should be, it can lead to slowing down response time. It’s also recommended to disable modules you may not need, as they can contribute to response time latency.

Troubleshooting DNS Issues

If you’re experiencing issues related to domain names, it’s likely caused by a DNS issue. You can use the `nslookup` command to confirm a website’s DNS entry. Here’s an example:

# nslookup -type=ns www.example.com
Server: 8.8.8.8
Address: 8.8.8.8#53

Non-authoritative answer:
www.example.com        nameserver = ns2.example.com
www.example.com        nameserver = ns1.example.com

In this example, we can see that the domain www.example.com is being pointed to the nameservers ns1.example.com and ns2.example.com. If there are no entries, or the entries are incorrect then that can lead to a DNS issue. You can use the `dig` command to further test the domain’s DNS entry.

Conclusion

Debian can be a highly capable web server OS when configured correctly. However, its flexibility can make it challenging to troubleshoot, so it’s important to understand some of the most common issues. I’ve outlined a few tips and tricks to help you troubleshoot any issues you may encounter when running Debian web servers. Hopefully this has been helpful and good luck!