Linux Pit

squid-deb-proxy

Squid-deb-proxy is a new package for Ubuntu 10.04, and it’s designed to make your life easier and allow faster updates if you manage more than one Ubuntu machine. Conceptually, squid-deb-proxy consists of two pieces, a client and a server. The server package is “squid-deb-proxy” and the client package is “squid-deb-proxy-client”. The “squid-deb-proxy” server package is basically a squid caching server, with an out-of-the box configuration that allows it to cache .deb packages and make them accessible to the local area network. The “squid-deb-proxy-client” package is basically an include file to your standard apt configuration that makes apt aware of the squid-deb-proxy.

To install the server, simply “sudo apt-get install squid-deb-proxy avahi-utils” on the machine that you wish the server to be on. This will install the squid caching server and the avahi (Bonjour) auto-configuration network utilities, and start both servers, so your new caching squid proxy will start broadcasting its availability on your network. Then, a “sudo apt-get install squid-deb-proxy-client” on each Ubuntu 10.04 machine (including the squid-deb-proxy server) will install the apt configuration. You’ll want to install the client on the server as well, so whenever the server downloads updates those updates get cached by the squid proxy. This will also allow the server to install already-fetched updates via the proxy.

Once this is done, squid-deb-proxy is transparent to the user. Each machine’s apt program will look on the network for a squid-deb-proxy, and if it finds one, it’ll pass its requests through that. The proxy will cache any .deb packages that come through it, and make them available for the next update client that needs them. The second client to request these same updates will pull them down from the squid proxy, rather than having to get them from the Internet. You get the benefit of a local repository without the hassle of setting one up!

The beautiful part about the squid-deb-proxy solution is that it is completely transparent. If you have the squid-deb-proxy client installed on your laptop and you choose to download an update while on a business trip, your laptop will grab the updates from the main repository in your sources.list file, since the proxy isn’t on that local area network, broadcasting its services via avahi. There’s no need to modify your sources.list in any way, because apt becomes proxy-aware automagically. It’s really cool stuff.

Nmap (“Network Mapper”) is a free and open source (license) utility for network exploration or security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network,

Nmap

what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics. It was designed to rapidly scan large networks, but works fine against single hosts. Nmap runs on all major computer operating systems, and official binary packages are avalable for Linux, Windows, and Mac OS X. In addition to the classic command-line Nmap executable, the Nmap suite includes an advanced GUI and results viewer (Zenmap), a flexible data transfer, redirection, and debugging tool (Ncat), and a utility for comparing scan results (Ndiff).

http://nmap.org/

Imagemagick is possibly the best & most powerful tool for handling large amounts of images.

http://www.imagemagick.org/

Imagemagick

I use it quite often when I need to compress hundreds of images and make thumbnails for them. Type the command needed, push enter and go make yourself a nice cup of coffee while your computer is doing the work for you.

For example the following command would resize all .jpg images in a directory to 640×480, with quality setting 86 (you can choose between 0 and 100) and strip EXIF data from them to make files even smaller:

Code:
find . -iname "*.jpg" -exec convert -resize 640x480 -quality 86 -strip {};

Other line commands:

animate

animate an image sequence on any X server.

mathematically and visually annotate the difference between an image and its reconstruction.

overlap one image over another.

interpret and execute scripts written in the Magick Scripting Language (MSL).

convert between image formats as well as resize an image, blur, crop, despeckle, dither, draw on, flip, join, re-sample, and much more.

display an image or image sequence on any X server.

describe the format and characteristics of one or more image files.

save any visible window on an X server and outputs it as an image file. You can capture a single window, the entire screen, or any rectangular portion of the screen.

resize an image, blur, crop, despeckle, dither, draw on, flip, join, re-sample, and much more. Mogrify overwrites the original image file, whereas, convert writes to a different image file.

create a composite image by combining several separate images. The images are tiled on the composite image optionally adorned with a border, frame, image name, and more.

a lightweight tool to stream one or more pixel components of the image or portion of the image to your choice of storage formats. It writes the pixel components as they are read from the input image a row at a time making stream desirable when working with large images or when you require raw pixel components.

Mtr combines the functionality of the ‘traceroute’ and ‘ping’ programs in a single network diagnostic tool.

As mtr starts, it investigates the network connection between the host mtr runs on and a user-specified destination host. After it determines the address of each network hop between the machines, it sends a sequence ICMP ECHO requests to each one to determine the quality of the link to each machine. As it does this, it prints running statistics about each machine. For a preview take a look at the screenshots.