networking

howto://troubleshoot networks with tracert

2011-01-24

How to use the tracert command to diagnose and troubleshoot networking issues.

howto://troubleshoot networks with tcping

2010-07-16

A great tool for troubleshooting TCP based connectivity is TCPING.EXE, by Eli Fulkerson. This post goes over how TCP works, and how to use this tool to troubleshoot networks.

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howto://troubleshoot networks with ping

2010-07-09

Call this network troubleshooting 101, where we’ll go over how to use the venerable PING command to do some basic network troubleshooting. This is probably something most of you will point n00bs to…it’s intended to help bring those n00bs up a notch in their troubleshooting skillz, which ultimately will help you too.

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howto://macgyver netstat into a sniffer-part two

2010-04-02

Welcome back! In part one of this post, we covered some of the functionality of netstat, and how we can use the command to diagnose our network connections at layers four, three, and two. In part two, we’re going to use that knowledge, the pipe (|) operator, and the find command to cobble together [...]

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howto://macgyver netstat into a sniffer-part one

2010-03-31

We’ve got a couple of good posts here at RetroHack about networking tools like portquery (here, and here,) and of course WireShark is my go to app every time the network is involved. But sometimes adding tools is just not an option. Either you don’t have/don’t want to take time, or you don’t have [...]

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howto://publish DNS using TMG 2010 or ISA 2006

2010-02-22

As a follow up to our recent post on using BIND9 servers as secondaries, today we’ll see how to publish our external DNS services using TMG 2010. Why would we want to do this, you ask? Simple…SE-KUR-I-TAH. Doing this, we are able to keep our BIND servers on the internal network, use secure web [...]

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howto://use BIND secondaries with an AD integrated primary DNS

2010-02-19

In a previous post we discussed setting up a DNS solution that combined scalability, flexibility, and security. We also designed it to be reliable and responsive. We even acknowledged that management would want it to be cheap, fast and good. Turns out management didn’t get the joke, and called me out on that…especially the [...]

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Designing your external DNS solution

2010-01-30

One of my favourite subjects is DNS. I really love resolvers and queries, discussing the relative merits of recursion versus iteration, the different types of records that are out there, and how to tune DNS just so. Primaries and secondaries, AXFR or IXFR, tuning the TTL of your individual records so that you can [...]

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howto://Use SPF records to combat domain spoofing

2010-01-16

Spam. When you’re talking about the Hormel product, love it. When you’re talking about unsolicited commercial email, I hate it with an abiding passion usually reserved only for the ankle-biter at Fox that cancelled Serenity. But any way you slice it, the bane of email’s existence is spam. Spam spam spam spam, lovely spam! [...]

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DNS self service on the cheap

2008-12-09

So last night, I got onto a bridge call at 2200, expecting to be off the call five minutes later. Not! I was supposed to put in a DNS change for a public facing site to accommodate a server migration. First they had cabling problems, then IIS was not happy, then the load balancer wasn’t [...]

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Disabling DHCP Authorisation checking in Windows

2008-08-20

While it shouldn’t be necessary, sometimes you find that you need to get around Windows’ process of checking with AD to see if it is authorised to service DHCP requests. This works in 2000, 2003, and should work in 2008 but has not been tested. To disable this check, create this registry key KEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DHCPServer\Parameters \DisableRogueDetectionand [...]

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Creating DNS records at the command line

2008-08-12

Given a number of records that need to be added to DNS, we can create a file with the necessary information, and then run a cmd to read the data in the file and create the necessary records in DNS. The following assumes that all records are to be created in the same zone. Create [...]

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