Setting Your MTU

So to follow up with the previous post about MTU and MSS, I wanted to show you how to set the MTU value on your computer. On most Unix-like boxes it is a fairly straight forward process to change your MTU. On Windows it gets a little trickier with registry changes and such things that can brick your computer.

How big is your packet, MTU / MSS and other TCP headaches

There are a lot of misperceptions about packet size and the various mechanisms that allow a packet to flow smoothly along a network path. In order to avoid fragmentation, which will hurt performance and potentially overwhelm some network devices, it is important for both ends to send the appropriate sized packet.

That Pesky Close Door Button

I work in a building with an elevator. Just about every day I am in the elevator with someone who is furiously pushing the door close button. Some days I just laugh to myself, others I need to restrain myself from throttling the individual. When I feel generous, I tell the person the truth, pushing that button won’t make the doors close faster.

Busy This Week, Here’s A tcpdump example

I have been behind in my posts, and I have quite a few items to get posted. Today I wanted to walk through an example of tcpdump can be useful when tracking down malicious traffic on your network. I am going to use the example of IrnBot to demonstrate a handy technique. IrnBot (named after the Scottish drink IrnBru), also popularly known as Rinbot, produces a lot of traffic on port 1433, 2967 and 139. It also opens up a connection to irc servers on the outside over port 8080.

Getting stats with awk, sort and uniq

I find myself sorting through logs all the time, and I have developed a couple of tricks for pulling the information I need out. With a little awk, sort and uniq magic you can get a great deal of info out of your logs.

More Fun With tcpdump and Resets

Here is another handy little trick for tcpdump that will help you identify some potential network issues. Often times when there is some trouble along the line you will see reset connections. This happens for many reasons and can be an indication of everything form a network program to a crashed application that suddenly stops responding.

Quicksilver Setup

When I was getting started using Quicksilver I was always hearing about all the great things it would do, but it was a struggle to get it set up the right way to get at that functionality. In order to prevent that struggle for others I am including my basic set up.

Selling the Quicksilver Magic

I keep telling everyone they need to try out Quicksilver, that it is the most amazing app. Then they ask me what it does, and I generally say, “it’s hard to explain.” Which it is. Then I fumble around to demonstrate a few things that never seems to do it justice. I need Ron Popeil to pop out and say, “but wait, there’s more.”

Quick Network Analysis With tcpdump

You see that light blinking like crazy on the switch, and want to see what it is that your systems is doing? If you are on a (u|li)n[i|u]x or bsd of some sort pick up a copy of tcpdump. If you are on OS X it is already included.

Network World IT Roadmap Chicago Roundup

These days I have found that most trade shows are hopelessly unimpressive, but I must say that Network World IT Roadmap Chicago was very useful. It was very targeted, so it was very relevant. Most of the presentations were good, the crowd was sufficiently nerdy, and the vendors were handing out swag again.