Archive for the ‘Wireshark’ category
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 […]
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.
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.
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 […]
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 […]
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 […]
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 […]
Name Resolution Denial of Service
Today I was using a combination of dumpcap and Wireshark to run a network forensics investigation against a server that may have been compromised. A couple of malicious files had been reported by the virus scanner, so I had to take a closer look at what it was doing in the network. Actually, dumpcap was […]
The notorious Wireshark “Out of Memory” problem
It is one of the most common question on the Wireshark Q&A site: “I have xyz gigabyte of memory, but still Wireshark crashes when I try to capture data”, with xyz being a more or less impressive (or even ridiculous) amount of memory. This is how a typical crash looks like (your mileage may vary):
Wireshark GeoIP resolution setup
One of the many features Wireshark provides is the name resolution for various protocol layers, and I have to admit that – at least for me – some of them are really helpful while others (well, one of them, to be more specific) annoy the hell out of me. I really like MAC layer resolution, […]