Tag: linux

VLANs on Linux

My home network has a Linux box running IPTables as it’s center point, and, since there are four networks, it has 4 NICs and 4 cables into the switch.  I kept running into problems with the NICs (they would reorder…

Unix Epoch + 1234567890 = Next Friday

I’m kind of an obsessive-compulsive when it comes to numbers (1, 2, 3, 4, 5…), so I’m fairly excited about next Friday (..6, 7, 8, 9, 10…) when Epoch time reaches 1234567890 at 18:31:30 on 13 February(…11, 12, 13, 14,…

Leap Second

Did anyone notice (or care about) the leap second?  I did neither.  Here’s some cool output from Kevin Oberman on the NANOG list, though. bash-2.05b# date Thu Jan  1 00:59:58 CET 2009 bash-2.05b# date Thu Jan  1 00:59:59 CET 2009…

Free and Awesome Network Tools

We all have limited budgets these days. Long gone are the days of unlimited resources and uncontrollable expansion of the network, so it’s important that any network dude or dudette pay attention to the open-source world. Below is a list…

A Simple BGP Lab with Dynamips/Dynagen

I assume you take every word I say to heart and that you’ve been using Dynamips/Dynagen for a few days now, right? Good. That’s a start, but let’s break down a simple lab to make sure everyone’s on the same…

Finding Hosts on Layer 2

Most firewalls should block [tag]ICMP[/tag] requests to them, so how do you know that your router or server has layer-2 connectivity to one? It’s pretty elementary, actually, but I’ve found that not a lot of people know this trick. If…

Using a Linux Box as a File Server

Ever heard of Samba? You should. Samba is an open-source project “that provides seamless file and print services to SMB/CIFS clients.” That’s from the project’s website, but what the hell does it mean? In a nutshell, it’s an open-source application…

Port Knocking

A few months ago, a friend of mine told me about the concept of port knocking, where you send packets to a server on certain ports to authenticate access to the box. A daemon running on your server detects the…