Tag Archives: Authentication

NTS Published as Standard

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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 Internet Engineering Task Force (IETF) published the Network Time Security protocol (NTS) as RFC 8915 on October 1, 2020. This new standard offers security mechanisms for the widely used Network Time Protocol v4 (NTPv4), which has been operated mostly unsecured until now. After almost eight years of development, global collaboration, and many interoperability tests of leading NTP software developers, NTS represents a mature security protocol. In this post, I’ll give you a short overview of the development progress of NTS and provide a list of public implementations and NTS secured time servers…

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Setting up NTS-Secured NTP with NTPsec

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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.

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Intro to NetworkMiner

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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).

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Network Time Security – New NTP Authentication Mechanism

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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 …

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Basic NTP Client Test: ntpdate & sntp

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During my work with a couple of NTP servers, I had many situations in which I just wanted to know whether an NTP server is up and running or not. For this purpose, I used two small Linux tools that fulfil almost the same: single CLI command while not actually updating any clock but only displaying the result. That is: ntpdate & sntp. Of course, the usage of IPv6 is mandatory as well as the possibility to test NTP authentication.

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NTP Authentication at Juniper ScreenOS

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Yes, ScreenOS is end-of-everything (EoE), but for historical reasons I still have some of them in my lab. ;D They simply work, while having lots of features when it comes to IPv6 such as DHCPv6-PD. However, using IPv6-only NTP servers is beyond their possibilities. :(

Anyway, I tried using NTP authentication with legacy IP. Unfortunately, I had some issues with it. Not only that they don’t support SHA-1 but MD5, this MD5 key was also limited in its length to 16 characters. Strange, since ntp-keygen per default generates 20 ASCII characters per key. Let’s have a look:

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NTP Authentication on Pulse Connect Secure

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I initially wanted to show how to use NTP authentication on a Pulse Connect Secure. Unfortunately, it does not support NTP over IPv6, which is mandatory for my lab. Ok, after I calmed down a bit, a configured it with legacy IP and got NTP authentication running. ;) Here’s how:

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Infoblox Grid Manager NTP Authentication

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Configuring NTP authentication on the Infoblox Grid Master is quite simple. Everything is packed inside the single “NTP Grid Config” menu. You just have to enter the NTP keys respectively key IDs and enable authentication on the appropriate servers. In the case of incorrect authentication values an error message is logged. Very good, since this is not the case on some other network security devices (Palo, Forti).

Too bad that it only supports MD5 while SHA-1 should be used instead of.

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Fortinet FortiGate (not) using NTP Authentication

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A security device such as a firewall should rely on NTP authentication to overcome NTP spoofing attacks. Therefore I am using NTP authentication on the FortiGate as well. As always, this so-called next-generation firewall has a very limited GUI while you need to configure all details through the CLI. I hate it, but that’s the way Fortinet is doing it. Furthermore the “set authentication” command is hidden unless you’re downgrading to NTPv3 (?!?) and it only supports MD5 rather than SHA-1. Not that “next-generation”!

Finally, you have no chance of knowing whether NTP authentication is working or not. I intentionally misconfigured some of my NTP keys which didn’t change anything in the NTP synchronization process while it should not work at all. Fail!

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Palo Alto Networks NGFW using NTP Authentication

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Everyone uses NTP, that’s for sure. But are you using it with authentication on your own stratum 1 servers? You should since this is the only way to provide security against spoofed NTP packets, refer to Why should I run own NTP Servers?. As always, Palo Alto has implemented this security feature in a really easy way, since it requires just a few clicks on the GUI. (Which again is much better than other solutions, e.g., FortiGate, which requires cumbersome CLI commands.) However, monitoring the NTP servers, whether authentication was successful or not, isn’t implemented in a good way. Here we go:

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Meinberg LANTIME NTP Authentication

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Operating NTP in a secure manner requires the usage of NTP authentication, refer to my Why should I run own NTP Servers? blogpost. Using the Meinberg LANTIME NTP appliance with NTP authentication is quite simply since it requires just a few clicks. Even adding more and more keys (which requires manual work on any other Linux ntp installation) is done within clicks. That’s the way it should be.

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NTP Authentication: Server Side

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As already pointed out in my NTP intro blogpost Why should I run own NTP Servers? it is crucial to leverage NTP authentication to have the highest trustworthiness of your time distribution all over your network. Hence the first step is to enable NTP authentication on your own stratum 1 NTP servers, in my case two Raspberry Pis with DCF77/GPS reference clocks.

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Packet Capture: Network Time Protocol (NTP)

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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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