Tag Archives: pcap

DNS Capture: UDP, TCP, IP-Fragmentation, EDNS, ECS, Cookie

It’s not always this simple DNS thing such as “single query – single answer, both via UDP”. Sometimes you have some more options or bigger messages that look and behave differently on the network. For example: IP fragmentation for larger DNS answers that do not fit into a single UDP datagram (hopefully not after the DNS flag day 2020 anymore), or DNS via TCP, or some newer options within the EDNS space such as “EDNS Client Subnet” (ECS) or DNS cookies.

I won’t explain any details about those options, but I am publishing a pcap with that kind of packets along with some Wireshark screenshots. Feel free to dig into it.

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6in4 Traffic Capture

Since my last blogposts covered many 6in4 IPv6 tunnel setups (1, 2, 3) I took a packet capture of some tunneled IPv6 sessions to get an idea how these packets look like on the wire. Feel free to download this small pcap and to have a look at it by yourself.

A couple of spontaneous challenges from the pcap round things up. ;)

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Packet Capture: Network Time Protocol (NTP)

What’s the first step in a networker’s life if he wants to work with an unknown protocol: he captures and wiresharks it. ;) Following is a downloadable pcap in which I am showing the most common NTP packets such as basic client-server messages, as well as control and authenticated packets. I am also showing how to analyze the delta time with Wireshark, that is: how long an NTP server needs to respond to a request.

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Single DNS Query – Hundreds of Packets

I was interested in how a recursive DNS server resolves DNS queries in detail. That is, not only the mere AAAA or A record, but also DNSSEC keys and signatures, the authority and additional section when testing with dig , and so on. For this I made two simple DNS queries to my recursive DNS server which resulted in more than 100 DNS packets at all. Wow.

In the following I am publishing a downloadable pcap so that you can analyse it by yourself. Furthermore I am showing some listings and screenshots to get an idea of the DNS resolution process.

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EIGRP Capture

And again: Here comes a pcapng capture taken for the dynamic routing protocol EIGRP. If you want to dig into EIGRP messages, download the trace file and browse around it with Wireshark. Since I used both Internet Protocols (IPv6 and legacy IP), MD5 authentication, route redistribution, etc., you can find many different messages in it.

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OSPFv3 with IPsec Authentication

Here comes a small lab consisting of three Cisco routers in which I used OSPFv3 for IPv6 with IPsec authentication. I am listing the configuration commands and some show commands. Furthermore, I am publishing a pcapng file so that you can have a look at it with Wireshark by yourself.

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OSPFv2 Capture

I already had an OSPFv2 for IPv4 lab on my blog. However, I missed capturing a pcap file in order to publish it. So, here it is. Feel free to have a look at another small lab with three Cisco routers and OSPFv2. Just another pcapng file to practise some protocol and Wireshark skills.

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MP-BGP Capture

For those who are interested in analyzing basic BGP messages: I have a trace file for you. ;) It consists of two session establishments as I cleared the complete BGP session on two involved routers for it. Refer to my previous blogpost for details about the lab, that is: MP-BGP with IPv6 and legacy IP, neighboring via both protocols as well, with and without password. The involved routers were 2x Cisco routers, one Palo Alto Networks firewall, and one Fortinet FortiGate firewall.

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IPv6 Upper Layer Protocol Samples

Some time ago I published a pcap that can be used to study basic IPv6 protocol messages such as ICMPv6 for Router Advertisements, Neighbor Solicitations, etc.: “Basic IPv6 Messages: Wireshark Capture“. You can use it to learn the basic IPv6 address assignment and layer 2 address resolution. However, that pcap does not include any upper layer protocols.

This time I captured a few application layer protocols that I used over IPv6 rather than over legacy IP. Common user protocols such as DNS, HTTP/S, IMAP, SMTP, as well as some network administration protocols: SSH, SNMP, and Ping. It is not that interesting at all ;) though you can use it to have some examples for Wireshark to prove that those application protocols are almost the same when run above IPv6 compared to IPv4.

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Internet’s Noise

If you are following the daily IT news you have probably seen many articles claiming they have scanned the whole Internet for this or that. Indeed there are tools such as the ZMap Project “that enable researchers to perform large-scale studies of the hosts and services that compose the public Internet”.

This time I was not interested in scanning something, but in the question about “how many scans happen during one day on my home ISP connection?” Or in other words: What is the Internet background noise as seen by almost any customer? For this I sacrificed my Internet connection at home for 24 hours, while a factory-resetted router established a fresh Internet connection (IPv6 & IPv4) without any end devices behind it. No outgoing connections that could confuse or trigger any scans. That is: All incoming connections are really unsolicited and part of some third-party port scans, worm activities, or whatever. Using a network TAP device I captured these 24 hours and analyzed them with Wireshark.

In this blogpost I will present some stats about these incoming port scans. Furthermore I am publishing the pcap file so you can have a look at it by yourself.

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Apple AirPlay Capture

I was interested in how Apple AirPlay works in my network. I am using an iPad to stream music to a Yamaha R-N500 network receiver. There is a great Unofficial AirPlay Protocol Specification which already shows many details about the used protocols. But since I am a networking guy I captured the whole process in order to analyze it with Wireshark.

Following is a downloadable pcap if you want to have a look at it by yourself as well as some Wireshark and NetworkMiner screenshots for a first glance.

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Nmap Packet Capture

I am using Nmap every time I installed a new server/appliance/whatever in order to check some unknown open ports from the outside. In most situations I am only doing a very basic run of Nmap without additional options or NSE scripts.

Likewise I am interested in how the Nmap connections appear on the wire. Hence I captured a complete Nmap run (TCP and UDP) and had a look at it with Wireshark. If you’re interested too, feel free to download the following pcap and have a look at it by yourself. At least I took some Wireshark screenshots to give a first glance about the scan.

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IKEv1 & IKEv2 Capture

It is probably one of the most used protocols in my daily business but I have never captured it in detail: IKE and IPsec/ESP. And since IKEv2 is coming I gave it a try and tcpdumped two VPN session initiations with IKEv1 main mode as well as with IKEv2 to see some basic differences.

Of course I know that all VPN protocols are encrypted – hence you won’t see that much data. But at least you can see the basic message flow such as “only 4 messages with IKEv2” while some more for legacy IKEv1. I won’t go into the protocol details at all. I am merely publishing two pcap files so that anyone can have a look at a VPN session initiation. A few Wireshark screenshots complete the blogpost.

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IKE Challenges

A few month ago I published many Layer 2/3 challenges on my blog. Beside the happy feedback I got some remarks that the challenges were to easy at all because you only needed the display filter at Wireshark while no deep protocol knowledge.

Ok, “challenge excepted” ;) here I have some more protocol related challenges for you: With this post I am publishing a pcap which has four site-to-site IPsec VPN connections inside. On the first half of the pcap all four of them are wrongly configured, hence, not working. –> What are the reasons for that? <–

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Wireshark Layer 2-3 pcap Analysis w/ Challenges (CCNP SWITCH)

While preparing for my CCNP SWITCH exam I built a laboratory with 4 switches, 3 routers and 2 workstations in order to test almost all layer 2/3 protocols that are related to network management traffic. And because “PCAP or it didn’t happen” I captured 22 of these protocols to further investigate them with Wireshark. Oh oh, I remember the good old times where I merely used unmanaged layer 2 switches. ;)

In this blogpost I am publishing the captured pcap file with all of these 22 protocols. I am further listing 46 CHALLENGES as an exercise for the reader. Feel free to download the pcap and to test your protocol skills with Wireshark! Use the comment section below for posting your answers.

Of course I am running my lab fully dual-stacked, i.e., with IPv6 and legacy IP. On some switches the SDM template must be changed to be IPv6 capable such as sdm prefer dual-ipv4-and-ipv6 default .

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