Using tshark to Watch and Inspect Network Traffic

Most of you probably have heard of Wireshark, a very popular and capable network protocol analyzer. What you may not know is that there exists a console version of Wireshark called tshark. The two main advantages of tshark are that it can be used in scripts and on a remote computer through an SSH connection.

Concerning Containers' Connections: on Docker Networking

Containers can be considered the third wave in service provision after physical boxes (the first wave) and virtual machines (the second wave). Instead of working with complete servers (hardware or virtual), you have virtual operating systems, which are far more lightweight.

My Network Go-Bag

I often get teased for taking so much tech hardware with me on trips—right up until the Wi-Fi at the hotel, conference center or rented house fails. I'm currently on vacation with my family and some of our friends from Florida, and our rental home has a faulty Wi-Fi router. Thankfully, I have a bag full of goodies for just this occasion.

Non-Linux FOSS: Flaky Connection? Mosh it!

Most of the work I do on computers is done via the command line. When I'm off on vacation somewhere, that means shoddy Wi-Fi and cell-phone tethering. Because cell-phone tethering gets expensive quick (I also have three teenage daughters with which I share a data plan), I try to use free Internet whenever I can. The biggest hassle with that method is dealing with broken SSH sessions.

Not So Dynamic Updates

Typically when a network is under my control, I like my servers to have static IPs. Whether the IPs are truly static (hard-coded into network configuration files on the host) or whether I configure a DHCP server to make static assignments, it's far more convenient when you know a server always will have the same IP.

Nmap—Not Just for Evil!

If SSH is the Swiss Army knife of the system administration world, Nmap is a box of dynamite. It's really easy to misuse dynamite and blow your foot off, but it's also a very powerful tool that can do jobs that are impossible without it.

Localhost DNS Cache

Is it weird to say that DNS is my favorite protocol? Because DNS is my favorite protocol. There's something about the simplicity of UDP packets combined with the power of a service that the entire Internet relies on that grabs my interest. Through the years, I've been impressed with just how few resources you need to run a modest DNS infrastructure for an internal network.

Wondershaper—QOS in a Pinch

In past articles, I've discussed my BirdCam setup and how it automatically archives video footage from my bird feeders to YouTube every night. That's a really cool process, but unfortunately, it saturates my upstream bandwidth in the evening.

EdgeRouter Lite

In the September 2014 issue, I mentioned my new router, and I got a lot of e-mail messages asking about how well it works. I can say without hesitation it's the nicest router I've ever owned. And, it was less than $100!

Non-Linux FOSS: Angry IP

The de facto standard for port scanning always has been the venerable Nmap program. The command-line tool is indeed very powerful, but I've only ever seen it work with Linux, and every time I use it, I need to read the man page to figure out the command flags.

LVM, Demystified

I've been a sysadmin for a long time, and part of being a sysadmin is doing more than is humanly possible. Sometimes that means writing wicked cool scripts, sometimes it means working late, and sometimes it means learning to say no. Unfortunately, it also sometimes means cutting corners. I confess, I've been "that guy" more than once. A good example is SELinux.

DNSSEC Part I: the Concepts

Like IPv6, DNSSEC is one of those great forward-looking protocols that unfortunately hasn't seen wide adoption yet. Before I implemented it myself, I could see why. Although some people think BIND itself is difficult to set up, DNSSEC adds an extra layer of keys, key management and a slew of additional DNS records.

Fight the Good Fight with SmokePing

My Internet connection is unstable. I do realize ISPs generally claim some downtime is expected, and service is not guaranteed, and countless other excuses are common for intermittent service. I currently pay $120/month for business-class service, however, and I expect to get reliable Internet access on a regular basis.

Non-Linux FOSS: Dive Deep with Wireshark

Before you say anything, yes, I know Wireshark is available for Linux. This time, however, Windows and OS X users get to play too. Wireshark is an open-source network analyzation tool that is really an amazing tool for troubleshooting a network.