DNS over VPN

We use Microsoft PPTP as our VPN solution at work. Although PPTP is not robust as a IPSEC based vpn, it is a lot easier to deploy and maintain. The biggest advantage is that most of the Microsoft OS’s (Windows 2000, XP, 98) have PPTP clients built into the OS. With IPSec, one has to deploy client software to the workstations. Recently SSL VPN‘s have made strides in the remote connectivity market and are even easier to maintain.. but that is for another post.

We had a very interesting problem with remote users trying access hosts/URLs in our network recently. We have several nodes in the network, which we publish on external and internal DNS. So users on the internal network would access the node via the internal IP address and get access to privileged areas, while public users accessing the node would be restricted to only some areas of the site. Users connecting to the office network via VPN were being directed to the external address even though their VPN was configured to use the remote gateway as the default gateway. This in theory should direct all traffic to the internal network. We scratched our heads for a while 🙂 and during the troubleshooting session discovered that the DNS of the node was resolving to the external IP address. So the workstation was using the DNS server provided by the ethernet interface rather than the PPTP interface!!!.. How do we solve this?? Well Google, to the rescue and we find this obscure article on Mircrosoft’s website, which tells you how to change the bind order of the network interfaces so that the PPTP interface is used by default. Since this is a registry change, we have to figure out a way to push this out to the workstations. But that is a story for another post :)..

Cacti – Installing on Windows

Cacti is a great tool to graph network utilization. I discovered it during my previous job to create some utilization graphs of satelite links. I highly admire the talent of the kid maintaining this software… Cacti can be used by any organization wanting to graph network utilization. It is also flexible enough to graph other stats (disk utilization, CPU utilization.. etc.)

I used Linux for all of my previous installs of Cacti. The whole install is very well documented. My team is still not very Linux savvy and wanted to try Cacti out in a Windows environment. There is adequate documentation for installing Cacti on Windows, but I ran into several issues when following this guide. If I was starting all over again, I would rather try this documentation. It is more up-to-date and detailed. The author missed mentioning that you have to change the “DocumentRoot” value in the Apache conf file.. But that is a minor issue.

Am still having issues with the scheduler tool in Windows to run the poller every 5 minutes. The scheduled job is only running when someone is logged into the server. As soon as you log off the server, the scheduler seems to be stopping. I will post an update as soon as I fix this.

MSFT Windows : Offer Remote Assistance

My team uses the “Remote Assistance” functionality offered in Windows XP pretty extensively. One of the problems with the tool for the tech support personnel is that there is no easy shortcut to “offer” remote assistance. One has to launch remote assistance, search for “offer assistance” and then click on the link that shows up. Sounds easy, but if you are doing it 20 times a day, gets rather irritating :)..

Here is a trick to bypass the search.. Right click on your desktop and go to “New” –> “Shortcut”. Enter “hcp://CN=Microsoft%20Corporation,L=Redmond,S=Washington,C=US/Remote%20Assistance/Escalation/Unsolicited/Unsolicitedrcui.htm” (without qoutes “”) into the location of the item box and hit next. Choose a name for the shortcut and click on Finish.

Double click on the shortcut and voila.. instant access to offering remote assistance :).

Microsoft related site

Looks like today is going to be a day of “Cool Sites” posts :). Here is a site maintained by Daniel Petri containing all sorts of MSFT articles. Daniel writes a lot of articles about issues that admins run into on a daily basis and he has some great practicle advice. Highly recommend visiting it regulary.

Excel : Import tables from web pages

Ran into a bit of a tough nut the other day. One of my colleagues was trying to gather data from a HTML page and run some reports. He could scrape the page and copy the data into Excel, but any operations he tried on the data errored out. He tried every trick in the book (change format of columns etc) but it didn’t help.

A bit of googling and found this new cool function in Excel 2003.

Go to “Data –> Import External Data –> New Web Query” in Excel and you check on this new cool method.

“F1” in Excel rules :)..