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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...
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My Network Gadgets
This post is not about software but hardware tools for network admins. Which network gadgets am I using during my daily business? At least three, namely the Airconsole, the Pockethernet and the...
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Why should I run own NTP Servers?
… since we all can use pool.ntp.org ? Easy answer: Many modern (security) techniques rely on accurate time. Certificate validation, two-factor authentication, backup auto-deletion, logs generation, and...
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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...
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NTP Server via DCF77 on a Raspberry Pi
In this tutorial I will show how to set up a Raspberry Pi with a DCF77 receiver as an NTP server. Since the external radio clock via DCF77 is a stratum 0 source, the NTP server itself is stratum 1. I...
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NTP Server via GPS on a Raspberry Pi
This post shows how to use a GPS receiver with a Raspberry Pi to build a stratum 1 NTP server. I am showing how to solder and use the GPS module (especially with its PPS pin) and listing all Linux...
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Updating NTP Servers
As always when you’re running own services you should update them regularly to have all known bugs fixed and security issues thwarted. Same for NTP servers based on Linux, as in my case running on...
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NTP Appliance: Meinberg LANTIME & SyncFire
In case you’re responsible for an enterprise network or data center you should care about NTP. Refer to “Why should I run own NTP Servers?“. As a hobby technician you might first think about Raspberry...
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Load Balancing NTP via F5 BIG-IP LTM
As you hopefully already know, you should use at least three different NTP servers to get your time. However, there might be situations in which you can configure only one single NTP server, either via...
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F5 BIG-IP Application Level NTP Health Checks
When configuring a pool of NTP servers on a F5 BIG-IP load balancer you need to choose how to check if they are still up and running. There is no specific NTP monitor on a F5 BIG-IP that does an...
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Infoblox Failover Debacle (Works as Designed)
What failover times do you expect from a network security device that claims to have high availability? 1 ms? Or at least <1 second? Not so for a fully featured Infoblox HA cluster which takes about...
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Using Case Sensitive IPv6 Addressing on a Palo Alto
IPv6 brings us enough addresses until the end of the world. Really? Well… No. There was an interesting talk at RIPE77 called “The Art of Running Out of IPv6 Addresses” by Benedikt Stockebrand that...
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NTP Authentication: Server Side
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...
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Meinberg LANTIME NTP Authentication
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...
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NTP Authentication: Client Side
Now that we have enabled NTP authentication on our own stratum 1 NTP servers (Linux/Raspbian and Meinberg LANTIME) we need to set up this SHA-1 based authentication on our clients. Here we go for a...
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NTP Authentication on Cisco IOS
This is how you can use NTP authentication on Cisco IOS in order to authenticate your external NTP servers respectively their NTP packets. Though it is not able to process SHA-1 but only MD5, you’re...
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Palo Alto Networks NGFW using NTP Authentication
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...
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Fortinet FortiGate (not) using NTP Authentication
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...
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Infoblox Grid Manager NTP Authentication
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...
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NTP Authentication on Pulse Connect Secure
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...
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