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Configuring NTP on a Linux client

Mon, 2012-02-27 00:14

I had to setup a Linux client this weekend and wanted NTP to sync the time with the rest of the systems on the network. Much to my surprise, ntpd wasn't installed on the box by default so I had to get it setup. Figured I'd share the steps I followed in a blog post to share the knowledge. Here it is...

To install ntpd, you can do it a couple different ways (such as downloading it from ntp.org and installing it manually) or you can use your favorite installer (I use apt-get):

sudo apt-get install ntp

Then you need to edit the /etc/ntp.conf file to point to the server you want to grab the time from. Since the installation started the process for me, I wanted to stop it before editing the conf file:

service ntp stop

Also, you might need to chmod the file first to allow writing to the file:

How to configure multiple NTP time sources in Windows Server 2008 (R2)

Sat, 2011-09-17 12:18
clock.jpg

Over the past few weeks, I noticed my computer's time was drifting several minutes behind. This actually caused me to be late to a couple different meetings because I kept working on my computer instead of leaving the house. Well, since it's a Saturday and I had some time to fix the problem once and for all, I wanted to share what I've learned since it took longer than I expected to configure NTP on a Windows Server.

It all began several months back when I setup a Windows 2008 R2 Server and thought "wouldn't it be cool if I set my desktop's clock to update from the server instead of a reliable external source?" So, I unwittingly redirected my desktop from its reliable 0.us.pool.ntp.org to my server's ip address with the assumption the server was already getting it's time from a default external source. Hence the source of my lateness months later.

Fast forward to today. I figured it would be a quick 5 minute fix to remote into the server, find some sort of ntp settings tab in a properties window, then add my multiple servers. I should have known better than to assume Microsoft would have added such a logical GUI feature. 

After searching the Internet, reading through several Microsoft technet articles, and testing multiple configurations, here's what I've got...

Common IPv6 Addresses

Thu, 2011-07-07 10:42
Just for quick reference, this post has a list of common IPv6 addresses (multicast and otherwise). I'm sure new ones will be added over time as standards are released, but for now these are the ones I'm planning on memorizing:

Common Unicast Addresses

2000::/3 Global Unicast
FC00::/7 Unique Local IPv6 unicast addresses
FE80::/10 Link Local
::/128 Unspecified for when a host has no address
::1/128 Loopback

Node-Local Scope Multicast Addresses

FF01::1 All Nodes
FF01::2 All Routers

Link-Local Scope Multicast Addresses

FF02::1 All Nodes
FF02::2 All Routers
FF02::5 OSPF
FF02::6 OSPF Designated Routers
FF02::9 RIP Routers

NTP and SNTP Configuration

Fri, 2010-09-24 07:00
clock.jpg

Have you reviewed your company's NTP configuration recently? Is it secure or can it be totally PWND? Let's talk about the "Why" and then we'll get to the How to configure NTP. 

First, what does NTP do? It provides the same time, enterprise wide. What happens if you log into a router on some distant continent that does not have the correct time? If you are trying to correlate logs, good luck! You are going to need more than a slide rule to match things up. 

Second, if a person with ill-intent decides to hack into your network, what better way to cover their tracks than to completely mess up your time settings. Imagine if the clocks were different on every device, there's no way you would be able to correlate what happened and when. 

So, that is why you need to have synchronized time. Take the bull by the horns like this is a military operation. Now let's talk about the how.

Free IP Address Management from Infoblox

Fri, 2010-09-24 01:12
infoblox_logo.jpg

IPAM is typically an acronym you don't hear until you start working on large networks. Most small to medium size networks have either a couple large networks (i.e., "the 10.0.0.0/8 network is over there, and the 192.168.0.0/16 network is over there...") or a few /24 subnets like 172.16.1.0/24 for Data, 172.16.2.0/24 for IP Phones, etc. 

However, when you start having to design solutions to integrate with hundreds of remote sites connected via a massive mpls network, multiple redundant data centers, and several campuses with dozens of buildings all interconnected, it becomes challenging to know where 10.37.225.64/28 is located without a spiffy higherarchical IP address design, great documentation, or just plain crawling the network with traceroutes and "show ip route" commands. So because of all that, engineers that work with large networks rely on IPAM to help organize and allocate IP addresses.

Handy Link: Stratum 1 Time Servers

Mon, 2009-08-31 13:07

Yes, I am still alive, but have been EXTREMELY busy over the last couple months. So, a quick post for a quick link that I always dig too long to find:
http://support.ntp.org/bin/view/Servers/StratumOneTimeServers
http://support.ntp.org/bin/view/Servers/StratumTwoTimeServers
Update: You can also point to the NTP server pool (in the US) at us.pool.ntp.org. Thanks Brent!

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Dr. Radut