Varun's Blog » Linux

Samba

varun — Sun, 26 Sep 2010 03:50:07 +0000

Good article on setting up samba on ubuntu.

AWLL7025 Dual-Band Wireless-N USB in Ubuntu

varun — Sun, 12 Sep 2010 07:50:20 +0000

I recently decided to move my old PC in the garage and run my web sites from there. One big problem though – no cat 5 in the garage. So, I thought lets get a cheap wireless-n USB adapter and I should be good. I purchased an AWLL7025 from amazon for $18. While the adapter worked great on a Windows 7 machine with the Vista drivers supplied by airlink, getting it to work on my linux machine running Ubuntu 10.0.4 wasn’t such a breeze. Here’s what I did to get it to work:

1. $lsusb in Ubuntu (device was not recognized, no driver loaded):

Bus 001 Device 002: ID 15a9:0012

2. Found out from the windows driver files that this device has a Ralink chipset rt2870.

3. Downloaded the Ralink rt2870 linux driver sources from their website and followed the instructions to compile the driver:

http://www.ralinktech.com/support.php?s=2

4. The one extra step that wasn’t in the readme was to add the device id (15a9:0012 from the lsusb output) in the appropriate source file before compiling the driver:

rtusb_dev_id.c: {USB_DEVICE(0x15A9,0×0012)}, /* Airlink AWLL7025 */

5. Loaded the compiled driver as per the instructions in the readme and I finally had a decent net connection (wireless-n speeds) from the PC in my garage!

A Good Primer on apt-get and dpkg

varun — Sun, 25 Apr 2010 02:10:51 +0000

Came across a good primer on using apt-get.

Ubuntu upgrades

varun — Mon, 27 Jul 2009 09:28:17 +0000

Spent some time upgrading my linux machines today. The Ubuntu network upgrade from 8.04 to 9.04 went smooth on one of the machines. I had to do the intermediate 8.10 first though. On the other machine (Armada M700), it ran into a kernel bug (specific to 9.04) that caused the machine to hang during startup, so I kept it at xubuntu (XFCE desktop) 8.10. Here’s the bug reference:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/393262

Also, in order to get the nomachines nx client to work here are the settings:

Select Desktop = Unix/Custom, and then
under Settings, “Run the following command” = /usr/bin/startxfce4
and also Options = New Virtual Desktop.

Monitoring Linux Performance with vmstat

varun — Wed, 07 May 2008 07:23:38 +0000

Found a good article on the subject of using vmstat to monitor virtual memory on a linux system. Here’s a link to the man page for vmstat.

varun.org has a new home

varun — Mon, 05 May 2008 10:37:19 +0000

It was high time to retire the nine year old 433 MHz box that was faithfully serving varun.org for all these years. The new “server” is a 1.6 GHz laptop running Ubuntu 8.04. While I was at it, decided to … Continue reading →

Hosting multiple web sites with Apache 2

varun — Mon, 05 May 2008 07:42:31 +0000

A good article on virtual hosting with Apache 2 that I used.

fail2ban: stop those ssh attacks

varun — Wed, 28 Jun 2006 07:49:31 +0000

Thought I’ll start blogging about Linux software that I tinkered around with and found useful. Few months back when I started hosting this site, I noticed my /var/log/auth/auth.info being flooded with entries like:

vplinux sshd[3227]: Connection from 218.14.146.205 port 44543
vplinux sshd[3227]: Failed password for root from 218.14.146.205 port 44543 ssh2
vplinux sshd[3236]: Connection from 218.14.146.205 port 44620
vplinux sshd[3236]: Failed password for root from 218.14.146.205 port 44620 ssh2

This indicates bute force attacks on the ssh service. These attacks are based on a rather simple idea: use an automated program for trying, one after the other, many combinations of standard or frequently used account names and likewise frequently used passwords. In my search to prevent such attacks, I found fail2ban that works rather well. It monitors (in daemon mode) or just scans log files (e.g. /var/log/auth/auth.info, /var/log/apache/access.log) and temporarily bans failure-prone addresses by updating existing firewall rules.