Uh, I wasn’t aware of so many different printing protocols. Do you? While I was trying to solve a little printing problem I took a packet capture of three different printing variants over TCP/IP: Raw via TCP port 9100, LPD/LPR via TCP port 515, and Apple’s AirPrint which uses the Internet Printing Protocol IPP. As always, you can download this pcap and have a look at it by yourself.
For the last couple of years, I captured many different network and upper-layer protocols and published the pcaps along with some information and Wireshark screenshot on this blog. However, it sometimes takes me some time to find the correct pcap when I am searching for a concrete protocol example. There are way too many pcaps out there.
This is supposed to change now:
I am using the WHOIS client a lot these days since I am migrating some RIPE objects such as ASes, inetnum/inet6num, etc. Meanwhile, I recognized that I have never captured this TCP port 43 protocol, nor looked at it with Wireshark. That’s what this post is all about, incl. a downloadable pcap for your own analysis.
VoIP calls, using the network protocols SIP/SDP and RTP, are the de-facto standard when it comes to voice calls. Wireshark offers some special features to analyze those calls and RTP streams – even with a nice “Play Streams” option, which discretely decodes your calls. Ouch. Again and again, frightening which privacy-related protocols are completely unencrypted on the Internet!
Here are some hints for Wireshark as well as a downloadable pcap with three calls in there. ;) Have fun!
Some time ago I published a post called DNS Test Names & Resource Records which lists many different FQDNs with lots of different RRs. You can use those public available DNS names to test your DNS servers or the like. However, I was missing a packet capture showing all these resource records as they appear on the wire. So now, here it is. If you are searching for some packets to test your tools for whatever reason, feel free to download this pcap.
This is a guest blogpost by Martin Langer, Ph.D. student for “Secured Time Synchronization Using Packet-Based Time Protocols” at Ostfalia University of Applied Sciences, Germany.
In the previous posts, I already introduced the Network Time Security (NTS) protocol and described the most important features. Although the specification process has not been completed, there are already some independent NTS implementations and public time servers (IETF106). NTPsec is one of the important representatives of this series and already offers an advanced NTS solution. In this post, I’ll give you a short guide to setting up an NTS-secured NTP client/server with NTPsec.
I am currently working on a network & security training, module “OSI Layer 4 – Transport”. Therefore I made a very basic demo of a TCP and UDP connection in order to see the common “SYN, SYN-ACK, ACK” for TCP while none of them for UDP, “Follow TCP/UDP Stream” in Wireshark, and so on. I wanted to show that it’s not that complicated at all. Every common application/service simply uses these data streams to transfer data aka bytes between a client and a server.
That is: Here are the Linux commands for basic lab, a downloadable pcap, and, as always, some Wireshark screenshots:
During my analysis of NTP and its traffic to my NTP servers listed in the NTP Pool Project I discovered many ICMP error messages coming back to my servers such as port unreachables, address unreachables, time exceeded or administratively prohibited. Strange. In summary, more than 3 % of IPv6-enabled NTP clients failed in getting answers from my servers. Let’s have a closer look:
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.
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. ;)
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.
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.
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.
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.
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.