Technology

Party time..

I think it is high time I started using Flickr to post my pictures. I take a ton of pictures (yes, I am one of those crazy guys, that carry a camera on them ALL the time) and haven’t found a way to share them with friends and family without maxing out the traffic on my hosted site. I have been looking at all the photo sharing, social tagging sites such as flickr, fotki, hello for quite some time, but never got around to creating an account and using them. I don’t like sites that require you to register just to look at pictures (kodak!!). We have too many accounts as it is, without having to register on a site just to look at some photos.

Long post short :).. Here is the first attempt to start logging my pictures online. The link to my pictures on flickr is
http://www.flickr.com/photos/kudithipudi/sets/72057594092170857/

P.S: If anyone wants me to delete their photos, pls shoot me an E-mail at vinay at kudithipudi dot org. Thx.

March 26, 2006 by Fun Technology Uncategorized Web 0

Another day.. another tech term

IDF – Intermediate Distribution Frame – Otherwise known as the wiring closet in floors or buildings that in turn connect to the core network closet

MDF – Main Distribution Frame – In layman terms, the core network/telecom cabinet/closet in a facility.

March 9, 2006 by Technology Uncategorized 0

Updating NFS Share permissions..

Wanted to add this for my future reference. To update the permissions on a NFS (Network File System) share, you need to edit the “/etc/exports” file and then run “/usr/sbin/exportfs -a” to update the share permissions.

Syntax of /etc/exports looks like
/dir/to/export host1.mydomain.com(ro,root_squash)

UPDATE : Looks like the NFS daemon caches DNS lookups when authenticating a client. Am not sure if this is only in older versions. After we updated the exports file, the server still kep erroring out with a “unresolvable reverse lookup” error. I finally had to restart the daemon to make it check on the DNS records for the accessing client.

March 6, 2006 by Linux Technology Uncategorized 0

What is NPA NXX ?

I am in the middle of ordering some data circuits for our new office and the vendor asks me for the address of the building where the circuits are going to be terminated. I give it to them and they come back with “what is the NPA NXX??” of the location. Now, I should admit that I haven’t been provisioning hardcode data circuits, but have ordered a bunch of T1s and DS3s during my career. I thought this was come kind of technical spec and swallowing my pride, asked the vendor what NPA NXX means.. and the answer..

“there are no dumb questions 🙂
the first six digits of a phone number“

Looking up on the web, gave me this information

NPA = (Numbering Plan Area code) The area code of a telephone number in the NPA system. The first NPA codes used 0 or 1 as the center digit, such as 201, 212, 301, 312, etc., designated as “N0/1X.” After July 1, 1995, all digits 0 through 9 are valid as the center digit, designated as “NXX.”

All I can say is “live and learn” :).

March 3, 2006 by Technology Uncategorized

UBUNTU : Quick tips

I have heard a lot about the new Linux distro Ubuntu and wanted to try it out on my test machine at home. I chose the “base” install, which apparently just installs the base packages to operate the machine as a server. Couple of things I had to do to get the system up and running

1) The root account in Ubuntu doesn’t have a password by default. This means that you cannot log in or “su” to root. This can be fixed by issuing the following command
“sudo passwd root”
while logged in as the user you create while installing Ubuntu

2) Configure the network interface (eth0, if you only have one) with a static IP address. This can be done by editing the “interfaces” file in “/etc/network“. My file looks as below after the edit

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).# The loopback network interface
auto lo
iface lo inet loopback# This is a list of hotpluggable network interfaces.
# They will be activated automatically by the hotplug subsystem.
mapping hotplug
script grep
map eth0

# The primary network interface
auto eth0
iface eth0 inet static
address 192.168.0.10
gateway 192.168.0.1
netmask 255.255.255.0
network 192.168.0.0
broadcast 192.168.0.255

The text in bold is what I edited

3) Configure apt-get (package installer) to use the Internet archives as the source. This is esp. useful if you don’t have the install CD anymore. This can be done by editing the “sources.list” file located in “/etc/apt/” and commenting out the line with cdrom as the source. In my case it looks like this
“# deb cdrom:[Ubuntu 5.04 _Hoary Hedgehog_ – Release i386 (20050407)]/ hoary main restricted“. If you have a different version of Ubuntu, the description might be different, but the source should still say deb cdrom.

January 5, 2006 by Linux Technology Uncategorized

Blogging from a browser

One of the challenges I have in writing blogs is choosing the right editor. I have been using w.Blogger to far and have been very satisfied with it. But it is an additional program that I have to install and launch. With the powerful flexibility that Firefox provides, I have been trying moving all my “functions” to it. I use the multiple search engine functionality built into it. I just discovered “performancing.com” today. It is a firefox addon to publish blogs.. Hooho.. Open source rules.

December 24, 2005 by Networking Technology Uncategorized

802.1x : RADIUS : IAS : Fiasco

We use 802.1x for our wireless security at work. The wireless controller uses Microsoft’s IAS as the RADIUS server. Recently during one of our maintenance windows, we installed a couple of critical patches and rebooted the IAS server. This was over the weekend and we didn’t check if wireless was working after the maintenance (one of the lessons learnt from his story :), put in automated monitoring so that you don’t have to worry about what services have come up or not after a maintenance window).

On Monday, our helpdesk gets swamped with calls of “wireless is not working”. We checked the controller and everything looked okay. Only error on the controller was that the RADIUS server was not responding. We checked the RADIUS server and the IAS service was running fine. But there were a ton of errors in the System event log with the following details

Access request for user XXXX\XXXXXX was discarded.
Fully-Qualified-User-Name = XXX.XXXX.NET/XXX.XXX/TECHNOLOGY/DEVELOPMENT/XXX XXXXXX
NAS-IP-Address = 192.168.128.10
NAS-Identifier = ACHIAS01IT
Called-Station-Identifier = 00-0B-85-06-0C-A0:wacker
Calling-Station-Identifier = 00-14-A4-28-4C-EE
Client-Friendly-Name = ACHIAS01IT
Client-IP-Address = 192.168.128.10
NAS-Port-Type = Wireless – IEEE 802.11
NAS-Port = 1
Proxy-Policy-Name = Use Windows authentication for all users
Authentication-Provider = Windows
Authentication-Server =
Reason-Code = 23
Reason = Unexpected error. Possible error in server or client configuration. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
“Unexpected error. Possible error in server or client configuration.“, now that is real informational :). We scratched our heads.. Thought it might be an issue with the controller (it was on an older firmware). Upgraded the firmware and rebooted the controller. Still no go. Same error. Finally frustrated, we opened up a case with MSFT. Even the eng. from MSFT was flabbergasted. The usual “Everything looks good, it should work!!”.

Finally we resolved the issue to an expired computer certificate for the IAS server. The certificate had expired a couple of weeks ago, but looks like the authentication was cached and when the server was rebooted, it caused the IAS service to error out. Renewing the cert caused the wireless clients to start authenticating immediately.

Am looking into what other services depend on a valid cert to work properly.

December 22, 2005 by Networking Technology Uncategorized Windows

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 :)..

December 14, 2005 by Networking Technology Uncategorized Windows

Gotta check this out..

I am still working on the Vegas trip post.. But here is something I stumbled upon. A very unique way of using the collective power of the web.

www.stumbleupon.com. This is a site, where you can tag interesting sites based on your interest, you can “stumble” on it. You can install a plugin for Firefox for it too. BTW.. Firefox 1.5 is out. If you haven’t tried it out yet.. Highly reccomend it. Fast, Small, Easy to use broswer as an alternate to MSFT’ Internet Explorer.

November 30, 2005 by Technology Uncategorized Web