Wireless Router Reloaded.

I got my first Linksys WRT300N three years back when it was still not a standard and flashed with DDWRT. But now I wanted more, better streaming, drag and drop NAS, Media server in built. I was looking at WNDR4000 from Netgear and Cisco E4200. Finally grabbed the Linksys E4200 as this is broadcom based and DDWRT should support. Specs are nice too. I plan to bridge my second wireless as a repeater and let it die with age.

I plugged in a 1 TB usb drive and it was showing up in share. Also just adding the Music folder to Media server made uPNP install on my Windows 7. Everything worked as expected. I streamed blue ray movies without any glitch on the Laptop. Added a uPNP Play on my HTC desire HD Android phone and music streaming just worked. Now i need to get a new LED TV and a AV receiver with a good set of speakers to stream this for my home theater experience.

Here is a pic of my setup:
My new E4200 and oldy WRT300N Cisco routers

Python error

While installing Python on windows 2008, R2 server we came across error “The application has failed to start beacuse its side-by-side configuration is incorrect. Please check the error log”

On further trying to dig there was no information on eventlog. Also came to know that the error was related with windows manifest file. While digging online I came across the trace command called sxstrace. If you run it on command line you get the description

C:Program FilesVMwareVMware vSphere CLI>sxstrace
WinSxs Tracing Utility.
Usage: SxsTrace [Options]
Trace -logfile:FileName [-nostop]
Enabling tracing for sxs.
Tracing log is saved to FileName.
If -nostop is specified, will not prompt to stop tracing.
Parse -logfile:FileName -outfile:ParsedFile [-filter:AppName]
Translate the raw trace file into a human readable format and save the re
sult to ParsedFile.
Use -filter option to filter the output.
Stop the trace if it is not stopped before.
Example: SxsTrace Trace -logfile:SxsTrace.etl
SxsTrace Parse -logfile:SxsTrace.etl -outfile:SxsTrace.txt

Once i started this command and had the python run in background the etl file was created. here you need to convert the etl file to human readable txt file using the second command. And there it was, clearly showing that we had missed installing .net framework.

Incoming on sachingopalkrishnan.com

For a week, http://www.sachingopal.net was down, as I was moving it to http://www.sachingopalkrishnan.com. During the move i messed up the db badly while running sql commands, and all my backups were too old for recovery. After extensive manual edits, finally the site is back with improved security

sachingopal.net will now forward on to here henceforth, before going down completely next year.


Just logged in to my ddwrt and a “PS” from root shows the wireless router password in plain “nas -P /tmp/nas.wl0lan.pid -H 34954 -l br0 -i eth2 -A -m 4 -k mypassword -s Sector7 -w 2 -g 3600”. This is ugly.

Windows Debugger.

While trying to debug a windows issue using windbg, I came across debuging sysmbols
not getting loaded and got an error “module load completed but sysmbols cannot be

The easiest fix is:
1. Start the WinDBG
2. Select File >, “Symbol File Path…”
c) Set the path


Here you need to create a folder caled sysmbols before adding this. And you should be done. Now you can debug the dmp files using windows.

Update: I found a windows symbols which can be downloaded. Do a google
for “Download Windows Symbol Packages and hopefully you may not have to
do the above. But for me right now it pulls down the symbols as long
as I have internet.

Linux Cache Thrashed

Recently I came across an application in my workplace which is still under test phrase thrashing cache on RedHat linux servers badly. If this application would run for an hour+ the Server would start slowing down and the only way out was restart the linux server.

Then I came across this:


Writing to this will cause the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become free.
To free pagecache:

* echo 1 > /proc/sys/vm/drop_caches

To free dentries and inodes:

* echo 2 > /proc/sys/vm/drop_caches

To free pagecache, dentries and inodes:

* echo 3 > /proc/sys/vm/drop_caches

As this is a non-destructive operation, and dirty objects are not freeable, the user should run “sync” first in order to make sure all cached objects are freed.

This tunable was added in 2.6.16.

Source: Linuxinsight
Source: Cyberciti.biz

Zimbra View mail disable

Do you have several admins who are looking administering Zimbra and you are concerned about all of them having access to viewing mails. Stop! Just issue these commands and keep the Admin password with you and they should be able Administer without “View Mail” options.

Commands to stop view mails from Zimbra, GlobalAdmin has be disabled:

#zmprov ma [email protected] zimbraIsDelegatedAdminAccount TRUE zimbraAdminConsoleUIComponents

#zmprov grr global usr [email protected] +adminConsoleRights
#zmprov grr global usr [email protected] -adminLoginAs

Is chkrootkit the best ?

Mostly when I suspect that there is rootkit presence on Linux, the first I would go for is I am sure mostly all admins prefer the same or rkhunter. Yesterday just of curiosity when I checked the chkrrootkit script I saw that it would check for the default locations where the rootkit infects. If a dedicated hacker completely re-engineers the code, I don’t think it would throw out a error. I believe that the speed with which it scans out results is also because of it. I may be wrong as i have not read the complete script but rare.
Digg it!

Snort on Centos64 bit.

I was just trying to install snort on one of the centos 64 bit servers. It took me a while to figure out that its not easy as configuring on a 32 bit. Here just paste this if you get struck

./configure –with-mysql –enable-dynamicplugin –with-libpcap-libraries=/usr/lib64/ –with-libpcre-libraries=/usr/lib64/–with-libnet-libraries=/usr/lib64/–enable-dynamicplugin LDFLAGS=’-L/usr/lib64 -L/usr/lib64 -L/usr/lib64/mysql’ –prefix=/var/local/snort-


Several times in my work and freelancing stage organisations I have come across organizations who have deployed rpm based distro for there developers primarily a fedora or a Centos. The only issue was how to update.Cfengine was the preferred choice what I always deployed, Till i discovered Spacewalk. Spacewalk is plain awesome and you can group you machines in categories for specific departments too other than servers, Monitor machines, Audit, Have kicstart deployed, geographically deploy updates or packages. Several Defence related organizations have deployed it where the machine are not connected to external network and updates and packages are taken by the Satelite server (The commercial one by RedHat here). Use it. RedHat is doing a awesome job till date by releasing codes for RedHat satelite server as Spacewalk, Directory server and many more.

Update: Google chrome just crashed while editing this post, a rare crash. Try it.

Opensource on steroids.

What happens when you join a fully open source company:

1. You have a fun time working.

2 You play with the latest tools.

3 You learn.

The last 4 months i have tried so many opensource tools that I cannot put all of”em here, But yes some of them are worth trying if you are a open source evangelist. Few which caught my attention are:




Syadmins: Try them out in your network, Its fun.


Forgot Freenac. And all this on network, how do you manage. I remeber using Terminal, then mRemote and today Visionapp 2009 (Best for Admin Managers). You?

One month….Last day.

Its been one month without Asmi and Mayuri. They are flying back today to bangalore. Here is how I lived:

1. Food was mostly Egg and bread.(Maid who makes food at my home is pathetic)

2 Never did workout (Not even one benchpress)

3. Internet, old family videos for soul.

4. Late night work at office.

5. Beer 🙂 and Friends

How do you spend time when your family is away ? Do you turn from  a health freak to couch potato in a day or two ?

I do,  Yes I do.

Ldap client settings.

I have more than 160 machines (100 = windows, 60 = Linux) on my network with LDAP as the authentication server. I plan to change the IP for the LDAP server, easy right. But what happens to the ldap client settings ? Is there a way I can keep the settings on the LDAP* server and push it automatically to clients.  Is there a way ?

Imagine manually going to all machines and running system-config-authentication or editing /etc/nsswitch.conf file.

Update: I know I know we can forward the existing IP* to the new IP or a scp script. But what I am looking for is to push Ldap client settings.

Godaddy and SSh.

Godaddy recently came up with ssh for there users. When I tried to activate it says

Status: Blocked – Your account is not SSH enabled.

Please Note:
* Your databases must be deleted before enabling SSH.

Whats this ? To enable a single service I need to backup my sqldatabase, let them delete, recreate again with the added risk of what if something goes wrong. Godaddy Go-to-mama.

Which OS?

I am with ubuntu 8.10 now. Left windows years back. Now what ? We build our own comfort levels everywhere: People, Places, Products… and Choosing a OS and sticking on is same. Time to change but what? MacOS, Freebsd..or  OpenBSD. They all are Unix based and I am good on that. I guess i have none to move on, to make myself uncomfortable, to Challenge.