Networking

Ease the security burden with a central logging server

Many administrators fall short of spending the necessary time monitoring log files. Because this is a critical security task, one of the best ways to accomplish it is with a central logging server. These tips will help you get started.

This article was originally published as part of TechRepublic's Security Solutions e-newsletter.

Every network device on your network has some type of logging capability. Switches and routers are extremely proficient in logging network events. Your organization's security policy should specify some level of logging for all network devices.

It's important to deny traffic you don't want in your networks, but you also need to know who's sending that traffic. Some resourceful hacker could be hammering away at your outside interface and eating up bandwidth and processes. You need to know where that traffic is coming from. Your access lists should be logging all denied ports and protocols.

But the truth is that admins typically don't log routers and switches. When a problem occurs, we just reboot them or restart an interface, and then chalk it up to a hardware glitch.

My advice: Don't go another day without setting up a centralized logging server with syslog. Nearly all routers and switches can send log traffic on UDP port 514 in a syslog format. It's just a matter of providing a secure platform to collect that information. I recommend setting up a Linux box to handle this syslog task. It's simple and inexpensive, and it provides data security to some of the most valuable information about your network.

When implementing a central logging server, you need to take a number of key steps:
  1. Secure the location: Place the log server in a physically secure location behind your firewall with an access list filtering traffic to the machine.
  2. Turn off all services: Configure the machine to only collect log files. Don't make the machine double as a print server or for hosting any other network services. It's a security device, and you need to turn off all unnecessary services.
  3. Turn off all Inetd services: The only running services in the Inetd configuration file should be syslog and SSH. Syslog receives the log files, and SSH allows you to view the logs.
  4. Disable Remote Procedure Call (RPC) services: RPC services are unnecessary and are enabled by default. Turn them off.
  5. Disable all unnecessary accounts: The only account necessary is a log administrator. Disable all other accounts.
  6. Specify time: If your logs are to have any coherent meaning, make sure to synchronize time on all devices using the same network time source.

These six simple steps will go a long way toward providing a secure and central location for all of your networked devices' log files.

Although setting up a logging server gives you another machine to manage, you gain a central point from which you can now read all of these valuable files. Before you begin pointing routers and switches to your new security device, prepare your logging server first.

Once your logging server is up and running, you'll have no excuse not to read your logs.
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