In this comprehensive guide, we will walk you through the process of enabling logging for the Bind DNS server on a CentOS 6.2 Linux server. This is particularly useful for logging all DNS queries. We will assume that the Bind9 chroot environment has been correctly set up. This guide is designed to be detailed and easy to follow, ensuring that even beginners can successfully configure Bind-Chroot logging.
Before we dive into the tutorial, it’s important to understand the role of DNS servers in web hosting. DNS, or Domain Name System, is a critical component of the internet infrastructure. It translates human-friendly domain names into IP addresses that computers use to communicate. Bind is one of the most popular DNS servers due to its robustness and flexibility.
Step 1: Creating a Symbolic Link to /var/log
The first step in this process is to create a symbolic link, also known as a symlink or soft link, to /var/log. This can be done using the ‘ln’ command with the ‘-sf’ option. Here’s how to do it:
[root@ns1 ~]# ln -sf /var/named/chroot/var/log/dns.log /var/log/dns.log [root@ns1 ~]# ln -sf /var/named/chroot/var/log/dns_queries.log /var/log/dns_queries.log
Step 2: Opening named.conf
The next step is to open the named.conf file. This file is the main configuration file for the Bind DNS server. You can open this file using any text editor of your choice. In this guide, we will use ‘vim’:
[root@ns1 ~]# vim /var/named/chroot/etc/named.conf
Step 3: Adding the Bind Logging Script to named.conf
Once you have the named.conf file open, you need to add the following Bind logging script:
logging {
channel log_dns {
file "/var/log/dns.log" versions 3 size 10m;
print-category yes;
print-severity yes;
print-time yes;
};
channel log_queries {
file "/var/log/dns_queries.log" versions 3 size 20m;
print-category yes;
print-severity yes;
print-time yes;
};
category default {log_dns;};
category queries {log_queries;};
category lame-servers { null;};
category edns-disabled { null; };
};
This script creates two logging channels: ‘log_dns’ and ‘log_queries’. The ‘log_dns’ channel logs general DNS information, while the ‘log_queries’ channel logs DNS queries. Both channels are configured to print the category, severity, and time of each log entry. The ‘lame-servers’ and ‘edns-disabled’ categories are set to ‘null’, which means that these categories will not be logged.
Step 4: Displaying the Last Lines on dns_queries.log
To display the last lines on dns_queries.log, you can use the ‘tail’ command with the ‘-f’ option. This command will display the last lines of the file and then output appended data as the file grows. Here’s how to do it:
[root@ns1 ~]# tail -f /var/log/dns_queries.log
This command will display logged DNS queries similar to the following:
02-Jun-2012 23:45:09.958 queries: info:client 192.168.1.52#64527: query: www.facebook.com IN A + (192.168.1.44) 02-Jun-2012 23:45:10.023 queries: info: client 192.168.1.52#55959: query: www.lqconsulting.com IN A + (192.168.1.44) 02-Jun-2012 23:45:10.047 queries: info: client 192.168.1.52#60625: query: digg.com IN A + (192.168.1.44) 02-Jun-2012 23:45:10.098 queries: info: client 192.168.1.52#51729: query: reddit.com IN A + (192.168.1.44) 02-Jun-2012 23:45:10.137 queries: info: client 192.168.1.52#58908: query: www.adroll.com IN A + (192.168.1.44) 02-Jun-2012 23:45:10.966 queries: info: client 192.168.1.52#49432: query: mail.google.com IN A + (192.168.1.44) 02-Jun-2012 23:45:11.077 queries: info: client 192.168.1.52#58493: query: alerts.conduit-services.com IN A + (192.168.1.44) 02-Jun-2012 23:45:13.781 queries: info: client 192.168.1.52#55403: query: plus.google.com IN A + (192.168.1.44) 02-Jun-2012 23:46:20.203 queries: info: client 192.168.1.52#54825: query: realtime.services.disqus.com IN A + (192.168.1.44) 02-Jun-2012 23:46:30.113 queries: info: client 192.168.1.52#52337: query: qq.disqus.com IN A + (192.168.1.44)
Commands Mentioned
- ln -sf – This command creates a symbolic link to a file or directory.
- vim – This command opens a file in the Vim text editor.
- tail -f – This command displays the last lines of a file and outputs appended data as the file grows.
FAQ
-
What is the purpose of the Bind DNS server?
The Bind DNS server translates human-friendly domain names into IP addresses that computers use to communicate. This is a critical component of the internet infrastructure.
-
What is a symbolic link?
A symbolic link, also known as a symlink or soft link, is a file that points to another file or directory. It’s a way to create a shortcut to a file or directory in the Linux filesystem.
-
What does the ‘tail -f’ command do?
‘tail -f’ is a command that displays the last lines of a file and then outputs appended data as the file grows. It’s commonly used to monitor log files in real time.
-
What is the named.conf file?
The named.conf file is the main configuration file for the Bind DNS server. It contains settings and directives that control the operation of the DNS server.
-
What is the purpose of DNS query logging?
DNS query logging is used to record all DNS queries that the server receives. This can be useful for troubleshooting, monitoring, and auditing purposes.
Conclusion
In conclusion, enabling logging for the Bind DNS server on a CentOS 6.2 Linux server is a straightforward process that involves creating a symbolic link, editing the named.conf file, and adding a Bind logging script. This guide has provided a step-by-step walkthrough of this process, making it easy for even beginners to follow.
By enabling DNS query logging, you can gain valuable insights into the DNS queries that your server is handling. This can be useful for troubleshooting issues, monitoring server performance, and auditing DNS queries. For more in-depth guides on managing your server, be sure to check out our articles on Apache, Nginx, and LiteSpeed servers.
Whether you’re running a dedicated server, a VPS server, cloud hosting, or shared hosting, understanding how to configure your DNS server is a crucial skill for any webmaster or website administrator.
