A couple of ways to find out what files are currently opened on your system:
In the base system, there is fstat :
FreeBSD Hypertext Man Pages: fstat
You can also list information about open files by using lsof found in ports/sysutils/lsof : Port description for sysutils/lsof
I always wondered how to check to see if anyone is currently using either ftp or http. Sometimes, if my DSL modem light is blinking furiously, I like to see what's going on. Early on in my server days, I noticed a problem once and it turned out some hackerz had slipped into my ftp site and were using it to trade malware! So I keep a close watch these days.
Anyway, I recently came across two methods that I think do this:
$ netstat -anf inet
$ sockstat
They both show current connections, and who is using them.
More in the firewall vein; here's a tool to help you build your firewall rules, by far the most complicated part of using a firewall - fwbuilder. It supports ipfw out of the box, and also purports to support ipfilter. Gotta get started on this trip myself.
One quirk, when using fwbuilder with IPFW, the divert to natd isn't
supported so I'm installing the rules with a little script that inserts the
natd rule appropriately.
---
#!/bin/sh.fw # Installs the rules generated by fwbuilder
ipfw delete 1 # delete the check-state rule at 00001
ipfw add 1 divert natd ip from any to any via# add new
divert rule at 1
ipfw add 2 check-state # re-add the check-state 2
---
I still haven't decided what firewall, if any, to use. Yeah, I know, I should have one, but I don't. I think there are pretty much 2 choices with FreeBSD - ipfw (explained in the FreeBSD docs) and ipfilter. Here's a good link to get you started if you go down the ipfw road:
What a great idea! A set of scripts that builds an image to burn on a CD. This image is a complete, bootable FreeBSD installation. This would be especially nice for doing full backups.
