Network Security guide for the home or small business network – Part 9 – Know your network
Once more into the breech… Ok you’ve taken account of the software and services on your pc. The next thing we need to talk about is knowing your network. Do you have any wireless access points? Not sure? Print servers? How many pcs? Are any of them portables? Public access? Are all of them secured?
What about your firewall and modem/router devices? Are they password protected? Do they still have the default passwords? These are all questions that need to be seriously thought about and answered. It’s time to make another list…
You should become familiar with what is normal on your network, the same way you got an idea of what is normal on your PC. My favorite network scanning tool is nmap (network mapper). Network scanning utilities should come with a warning. Only use these to scan and audit networks that you legitimitely have access to. This kind of scanner could be interpreted as a prelude to attack if misused. Information gather COULD be the first signs of an attempted cracking of a system.
In other words, use these tools on systems OUTSIDE your control at your risk. That much said, within your own LAN, if you are the administrator – go for it. If your users have “noisy” personal firewalls that talk about every “attempted breakin” they may get some messages when you do a scan, so keep that in mind. Some personal firewalls like to tell how good a job they’re doing protecting you…
This can be a good tool for getting to know what’s normal on your network AND noticing services that are running on the LAN. If you have a larger network that might not be considered a “trusted” network, it can be a useful tool for seeing what “low hanging fruit” an untrusted intruder could run across. If you’re in that situation it would be worth investigating EVERY open service on the LAN and disabling what is unnecessary (treat it with the same policy as internet available services – NO unless there’s a REALLY GOOD reason.)