Simple Data Compression Algorithms in Common Lisp

Common Lisp implementation of some data compression algorithms — Run-Length, Huffman, and Shannon–Fano Encodings — that I have written during my graduate course "Data Compression".

Internet connection sharing using iptables

Scenario ― I have several virtualbox GUEST machines, using an internal network on my PC. Now, I wanted to share host machine's internet connection to guest machines. I searched on the web how to do it using iptables. Most of the solutions seem too complex. Here is a working simple solution (found on centos documentation)

On Host Machine — type these commands in Terminal.

thura @ ~ $ sudo iptables -A FORWARD -i vboxnet0 -j ACCEPT
thura @ ~ $ sudo iptables -A FORWARD -o eth1 -j ACCEPT
thura @ ~ $ sudo iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE

That's it. Now you can access the external network of host machine from guest machines. To access Internet, you may need to edit /etc/resolve.conf in your guest machine.

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 8.8.8.8

if_nametoindex, if_indextoname functions for python using ctypes

I needed to use if_nametoindex, if_indextoname functions for one of my packet capturing programs. So, here is my python wrapper for those functions using ctypes.


PS: You will need this only for python2.x. Those functions are available in socket module starting since python 3.3.

Using Prolink Wireless Nano USB Adapter on Ubuntu

Recently, I purchased a prolink nano usb wireless adapter WN2001. However, when I tried to plug it into my ubuntu box, I am getting "hardware disabled errors".

trhura @ ~ $ sudo rfkill list
0: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: yes

This can be fixed by reloading the wireless module with swenc option.

trhura @ ~ $ sudo rmmod -f rtl8192cu; sudo modprobe rtl8192cu swenc=1 debug=5