Did you know that you can easily decrypt TLS (mostly HTTPS) traffic with Wireshark? Well, only if you have the keys. ;) This really is a game-changer if you’re stuck with troubleshooting encrypted data. Let’s do an example:
Tag Archives: Ultimate PCAP
Protocol Independent Multicast (PIM) Capture
You never stop learning. One topic that hadn’t crossed my path in the past decade is: Multicast. Whew. Alongside all the technical literature, online presentations, and various blog posts, I decided to approach it the classic way – through packet captures. ;)
So here’s a new part of the #UltimatePCAP, which contains quite a bit of PIM traffic, including Hello, Join/Prune, Register (via unicast!), and more. Of course, for IPv6 and legacy IP (IPv4). Let’s have a look:
Continue reading Protocol Independent Multicast (PIM) Capture
DNS Tunneling: iodine
This post guides through a basic DNS tunneling setup with the usage of the appropriate tool “iodine“. It shows how DNS tunneling works and lists the commands needed to run this type of attack. That is, you can tunnel IPv4 packets through this DNS channel via the (internal) recursive DNS resolver! Nice approach. ;)
In the end, I’m pointing out how to block these tunnelling attempts with the DNS appliances from Infoblox, and the firewalls from Palo Alto Networks and Fortinet.
DNS Packet Capture: DoT, DoH, DoQ, DoH3
While I was working on my presentation about “Secure DNS” for this year’s SharkFest, the Wireshark Developer and User Conference, I recognised that I’m still missing some DNS-related packet captures in the Ultimate PCAP, that is DNS over TLS and DNS over HTTPS. And while working on it with the DNSDiag toolkit (thanks, Babak!), I came across DNS over QUIC and DNS over HTTP/3. 😂 Here we go:
Path MTU Discovery
One of the mysteries for me in IP networks was the Path MTU Discovery (PMTUD) process. I’ve seldom seen any problems with the MTU at all. Fortunately, while troubleshooting some router issues, I captured several ICMP “packet too big” errors along with the original packets. 👍🏻
Let’s have a look at those PMTUD processes for IPv6 and legacy IP with Wireshark. Of course, these captured connections are part of the Ultimate PCAP as well, hence, you can download the most current version of it and analyze it by yourself.
Joining an Active Directory: A Packet Capture
What happens on the network if you’re joining a Microsoft Active Directory domain? Which protocols are used? As I suspected, it’s a bit more complex than just seeing a single known protocol like HTTPS. ;)
Since a PCAP is worth a thousand words, I captured the process of a Windows PC joining an AD. Let’s have a look at it with Wireshark and NetworkMiner. And, as always, you’re welcome to download the packet capture to analyse it by yourself.
Continue reading Joining an Active Directory: A Packet Capture
Some more Mail Captures
Email is still the most common communication protocol on the Internet. And since I was missing some variants of the related protocols, IMAP, POP3, and SMTP in the Ultimate PCAP, I did some captures. ✅ Here are a few details.
More Capture Details III
Another update of the Ultimate PCAP is available. Again, there are some special new packets in there which I want to point out here. Feel free to download the newest version to examine those new protocols and packets by yourself. Featuring: SNMPv3, WoL, IPMI, HSRP, Zabbix, Pile of Poo, and Packet Comments. ✅
Stateful DHCPv6 Capture (along with Relaying)
For my IPv6 training classes, I was missing a capture of a stateful DHCPv6 address assignment. That is: M-flag within the RA, followed by DHCPv6 messages handing out an IPv6 address among others. Therefore, I set up a DHCPv6 server on an Infoblox grid and furthermore used a Palo Alto NGFW as a DHCPv6 relay to it. I captured on two points: from the client’s point of view (getting to the relay) and from the server’s point of view (unicast messages from the relay). And since I was already there anyway, I additionally captured the same process for DHCPv4. So, here we go:
Continue reading Stateful DHCPv6 Capture (along with Relaying)
RADIUS & TACACS+ PCAP
Again two more commonly used network protocols for the Ultimate PCAP: the Remote Authentication Dial-In User Service (RADIUS) and the Terminal Access Controller Access-Control System Plus (TACACS+) protocols. Captured with quite some details:
Who sends TCP RSTs?
At SharkFest’22 EU, the Annual Wireshark User and Developer Conference, I attended a beginners’ course called “Network Troubleshooting from Scratch”, taught by the great Jasper Bongertz. In the end, we had some high-level discussions concerning various things, one of them was the insight that TCP RSTs are not only sent from a server in case the port is closed, but are also commonly sent (aka spoofed) from firewalls in case a security policy denies the connection. Key question: Can you distinguish between those spoofed vs. real TCP RSTs? Initially, I thought: no, you can’t, cause the firewalls out there do a great job.
It turned out: you can!
Accessing IPv6-only Resources via Legacy IP: NAT46 on a FortiGate
In general, Network Address Translation (NAT) solves some problems but should be avoided wherever possible. It has nothing to do with security and is only a short-term solution on the way to IPv6. (Yes, I know, the last 20 years have proven that NAT is used everywhere every time. ?) This applies to all kinds of NATs for IPv4 (SNAT, DNAT, PAT) as well as for NPTv6 and NAT66.
However, there are two types of NATs that do not only change the network addresses but do a translation between the two Internet Protocols, that is IPv4 <-> IPv6 and vice versa. Let’s focus on NAT46 this time. In which situations is it used and why? Supplemented by a configuration guide for the FortiGates, a downloadable PCAP and Wireshark screenshots.
Continue reading Accessing IPv6-only Resources via Legacy IP: NAT46 on a FortiGate
Linux’s Traceroute
The other day I just wanted to capture some basic Linux traceroutes but ended up troubleshooting different traceroute commands and Wireshark display anomalies. Sigh. Anyway, I just added a few Linux traceroute captures – legacy and IPv6 – to the Ultimate PCAP. Here are some details:
Adding some packets: RARP, SNAP, MPLS & More
The other day, I was searching for a trace file with a decent protocol mix that could be used to introduce a few colleagues to Wireshark. This brought me to Johannes Weber and his Ultimate PCAP.
To get a first impression of a trace file, I used Wireshark’s protocol hierarchy – and boy, that’s a lot of protocols. This was not exactly what I was looking for: This single trace file holds snippets from 2014 to 2020 with a myriad of protocols and IP networks. Unfortunately, it’s nothing like the protocol mix found in a network analysis project.
Nevertheless, the trace file caught my interest as a long-time Wireshark user. After nearly 20 years of network analysis, I had my own collection of traces with a few odd frames. To my big surprise, I had recorded a few protocols that are not yet part of the Ultimate PCAP.
So here is my small contribution to this collection:
Continue reading Adding some packets: RARP, SNAP, MPLS & More
More Capture Details II
An updated version of the Ultimate PCAP is available. It features some more network protocols that I will depict in this blog post. It’s getting more special since the most common protocols were already in there. ;)