Networking on traviscj/blog

debugging internet

Tue, 28 Oct 2014 00:00:00 +0000

My standard plan for debugging internet connections:

Can we reach stuff from some other device?

Usually, connection problems are something like “My iPad isn’t working,” which is caused by a flash of light in the sky, like when Swamp gas from a weather balloon gets trapped in a thermal pocket and reflects the light from Venus."

So try something other than your iPad on your WiFi to isolate whether it is a WiFi network problem or a “iPad"problem.

SSL Cert Reissue

Wed, 09 Apr 2014 00:00:00 +0000

Like many others, I have been hit by the heartbleed bug, which kinda sucks. I don’t use SSL for anything very critical, but I do use it at [tcj.io tcj.io], my “projects” website. My host, Linode, has done a great job of providing tutorials on how to deal with the situation. The obvious first step (a couple of days ago) was to upgrade openssl itself:

apt-get update
apt-get upgrade

But this only prevents the server from leaking keys going forward. Since the vulnerability was in the wild for quite some time, I thought it prudent to reissue the certificates as well. Now that I had a bit more time, I went ahead and did a reissue to make sure that nothing going forward gets leaked. This is (as usual) a bit annoying, because of the verification procedure at [Gandi gandi.net]. Otherwise, they’re pretty solid though, so I guess I’ll give them a pass on this one. And they did allow a reissue without revoking, so that’s a good step!

Ditching the consumer grade wireless router

Fri, 24 Jan 2014 00:00:00 +0000

My fiancée and I both spend a fair bit of time working from home, so we notice downtime almost immediately. We had a NETGEAR WNDR3400 which periodically disconnected one or the other of us, or just didn’t seem very zippy anymore. I was originally considering a top-of-the-line router, such as an Airport Extreme, a NETGEAR Nighthawk AC1900, or an ASUS RT-AC66U.

I had been looking into alternatives for a while, and decided to pull the trigger on the following setup:

website basics

Fri, 15 Feb 2013 00:00:00 +0000

Several of my classmates in graduate school are considering making websites around now, and have asked me to explain it. I figured I’d explain the stack as I have it set up, and where you could make tradeoffs. For now, I’m not going to include too many detail here; I just want to outline the possibilities and lingo so that researching options is a bit easier for the uninitiated.

First off, many people are perfectly happy to use the school’s email and department web space. If you only want to have a list of relevant papers and soforth, then this is a fine approach. See the very bottom of this post for a couple potential ideas for organizing it.

More cracking D-Link Files

Wed, 27 Jun 2012 00:00:00 +0000

Somehow, in the process of a router reconfiguration, I reset the password without the new password getting saved into 1Password. So I found myself locked out of my own router. I was about to reset it, thinking, “Hey, at least I have a backup of the settings from 2 nights ago!” and then realized, “I bet that settings file has the password right in it.”

Googling around a bit turned up this guy, but he only wrote VBA and a Windows binary. His pseudo-code looked pretty easy to translate into Python, so I did just that. Here’s the result: D-Link DIR615 B2 v2.25 Decoder (no encoder, yet…)

TiVo Router Project

Sun, 01 Mar 2009 00:00:00 +0000

My girlfriend’s TiVo only has an ethernet port. Well, technically, it only has a USB port. We went looking for a TiVo compatible Wifi adapter but were less than successful. We did manage to find a USB-ethernet converter at Fry’s Electronics, though. But this means it requires a machine there to bridge from Wireless to the wired port, which is a bit of a hassle on her Windows Vista laptop(though, honestly, what isn’t a pain in Vista? </soapbox>).

GenHosts

Tue, 24 Feb 2009 00:00:00 +0000

Winter quarter 08, the hosts.allow files used by tcpwrappers was getting unwieldy. For one thing, we had certain groups of hosts that were all allowed to connect to eachother anywhere, some groups that were only allowed one port on one computer, some that were allowed certain parts of machines. It was basically a mess to try and keep up with it. So I wrote a set of scripts to let us update one place and have it synchronize everywhere else, all in very simple XML files.

Johnson vs Acronis

Sat, 02 Aug 2008 00:00:00 +0000

The story goes something like this: Originally, we used external hard drives plugged in via USB to our servers to back up our servers. This worked well, except that we had two external drives and 7 servers. About this time I started working this job and immediately set up a MediaWiki website for storing documentation and a Mantis Bug Tracker website for storing information about ongoing projects–I think I’ll try to write a post about that at some point as well. Anyways, these two websites originally ran on my personal webserver in Prosser, but we decided to run them on a company-owned server instead, and that this new machine could act as both a backup server and a webserver for those two websites.

MRTG

Sat, 30 Jun 2007 13:00:00 +0000

So, another day, another (minor) problem. I had connected to a server with KDE instead of our usual GNOME interface. Which probably would have been fine except that KDE had a screensaver that sucked up the CPU. Which also would have been fine, if it hadn’t been a server that everyone else used. Oops. RRDtool and MRTG would have shown a CPU spike which I could have investigated.

Cacti

Sat, 30 Jun 2007 12:00:00 +0000

So, rrdtool is pretty sweet, but it’s somewhat of a pain to set up. So… we use Cacti. It’s amazing. Supposedly it’ll integrate with Nagios as well, and then all of this data will be at our fingertips. For now, I just set it up on my server that’s probably going to go down shortly. In any case, I feel like this project is somewhat coming together. Nagios is great for what’s going on right now, cacti needs a way to know what’s going on right now–A match made in heaven, or something.

RRDTool

Fri, 29 Jun 2007 14:00:00 +0000

I have apparently been missing out. There’s a really neat little unix tool called ‘rrdtool’ that uses a fixed-size database to look at how something changes over time. I think I’ll use it to monitor server load… and possibly network traffic.