Archive for the ‘Wireshark’ category

1. Determining TCP Initial Round Trip Time

   I was sitting in the back in Landis TCP Reassembly talk at Sharkfest 2014 (working on my slides for my next talk) when at the end one of the attendees approached me and asked me to explain determining TCP initial RTT to him again. I asked him for a piece of paper and a pen, […]

2. Wireshark File Storage

   Sometimes it is important to know how Wireshark captures packets, and when it is writing them to disk. One of the common questions is “how can I avoid writing packets to disk, and just capture them in memory?”.

3. Sharkfest 2014 Recap

   Sharkfest 2014 is over, and once again it was an amazing conference. It was probably the best of them for me, for a number of reasons:

4. The drawbacks of local packet captures

   Probably the most common way of capturing network data is not a decision between SPAN or TAP – it is Wireshark simply being installed on one of the computers that need to be analyzed. While this an easy way to capture network packets it is also an easy way to get “wrong” results, because there […]

5. TCP Server slamming the door

   After doing a lot of analysis sessions on TCP connections there are some patterns that you see again in a trace every once in a while. And often it comes in handy to remember what the situation was and what the circumstances were that led to the trace showing what it did.

6. IPv6 DHCP flood

   A few days ago I took a capture for some reason and saw something unexpected that had nothing to do with what I wanted to check: there were tons and tons of DHCPv6 packets trying to renew an IPv6 address in a never ending stream of packets, and really fast, too.

7. Tweaking Wireshark Columns and Decodes

   It’s a funny thing about using Wireshark – I think I am pretty good at using it in an efficient way, but there are always some new tricks that I learn every once in a while. The Multi IP layer problem Maybe you have seen this in a trace before: some packets contain more than […]

8. Happy Birthday, Wireshark!

   15 years ago, Wireshark was “born”, so happy birthday! Take a look at the official Wireshark Blog for Gerald’s post. And watch Gerald’s keynote he did at Sharkfest 2013. And, of course, the funny video about how it was all Karen’s idea – which Gerald, at the time it was shown at Sharkfest, had no […]

9. Sharkfest 2013 Recap

   Yesterday I returned from the annual Wireshark conference, Sharkfest 2013, and once again it has been a great conference. I had four talks (well, actually I had three, but one was scheduled to run twice and it looks like I never do a talk the same way), and one of them I did together with […]

10. Spurious Retransmissions

    Update: since Wireshark version 1.12 is out, lots of people look for the meaning of “tcp spurious retransmission” info message, so I changed the post a little to make it easier to find what you’re looking for. Today, while doing a lot of testing of my trace handling code as well as in preparation for […]