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.
If you’re into DNSSEC, you’ll probably have to troubleshoot or at least to verify it. While there are some good online tools such as DNSViz, there is also a command-line tool to test DNSSEC signatures onsite: delv.
As you might have noticed, I am playing a lot with NTP these days. Having a networking background I also like Power over Ethernet. So what’s more obvious than using a PoE-powered NTP display for test purposes? ;D
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.
Probably the biggest prejudice when it comes to IPv6 is: “I don’t like those long addresses – they are hard to remember.” While this seems to be obvious due to the length and hexadecimal presentation of v6 addresses, it is NOT true. In the end, you’ll love IPv6 addresses in your own networks. This is why – summed up in one poster:
This is a guest blogpost by Erik Hjelmvik, an expert in network forensics and network security monitoring at NETRESEC.
Wireshark is the default goto tool for analyzing captured network traffic for most network engineers. But there are a few other free and open source alternatives that are sometimes overlooked, one of which is NetworkMiner (disclaimer: I’m the creator of NetworkMiner).
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:
Continue reading Basic TCP and UDP Demos w/ netcat and telnet
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.
The Network Time Security protocol (NTS) is close to completion as an Internet standard and will replace the existing security mechanisms in NTP. The introductory article on NTS describes the basic communication process as well as the most important features. Despite high-security efforts, NTS also has its limitations. In this blogpost, I list the strengths and weaknesses of the new authentication mechanism and describe them briefly.
Continue reading Network Time Security – Strengths & Weaknesses
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 many areas, the use of authentication mechanisms in NTP is important to prevent the manipulation of time information by an attacker. For many years, NTP has been offering solutions such as a Symmetric Key based method and the Autokey approach. However, both have serious disadvantages, for which reason they are rarely used to secure NTP connections. After years of development, a new standard is to be adopted in 2020 that solves the problems of the current mechanisms and offers a real alternative. First implementations of the so-called Network Time Security protocol (NTS) are already available and interoperate with each other …
Continue reading Network Time Security – New NTP Authentication Mechanism
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:
Continue reading Incorrect Working IPv6 NTP Clients/Networks
This is a guest blogpost by Jasper Bongertz. His own blog is at blog.packet-foo.com.
Running your own NTP server(s) is usually a good idea. Even better if you know that they’re working correctly and serve their answers efficiently and without a significant delay, even under load. This is how you can use Wireshark to analyze the NTP delta time for NTP servers:
I am participating in the NTP Pool Project with at least one NTP server at a time. Of course, I am monitoring the count of NTP clients that are accessing my servers with some RRDtool graphs. ;) I was totally surprised that I got quite high peaks for a couple of minutes whenever one of the servers was in the DNS while the overall rate did grow really slowly. I am still not quite sure why this is the case.
For one month I also logged all source IP addresses to gain some more details about its usage. Let’s have a look at some stats:
Continue reading Stats from Participating the NTP Pool Project
You have a running NTP server with a static IP address? What about joining the NTP Pool project by adding your server to the pool? You will give something back to the Internet community and feel good about it. ;)
It doesn’t matter if you’re running a Raspberry Pi with GPS/DCF77 on your home, or a fully-featured NTP appliance such as the ones from Meinberg on your enterprise DMZ. Just a few clicks and your server will be used by the NTP Pool’s round-robin DNS. Here’s a simple tutorial:
Continue reading Adding your NTP Server to the NTP Pool Project