Internet applications enable you to make full use of your Internet connection. Web browsers, Email clients, Instant Messengers, and more are included in this category.
Rekonq is the default web browser included with Kubuntu.
Konqueror was the prior default web browser included with Kubuntu.
KGet (Download Manager) plug-in for Konqueror
sudo apt-get install kget
Mozilla Firefox is the ubiquitous web browser. Based on open source components, it is trademarked and cannot be altered or re-distributed with any change that involves the name or trademarks. Install the current version:
sudo apt-get install firefox
- A KDE-optimised version of Firefox is available from the Blue Systems (the current sponsor of Kubuntu) Launchpad repository. Follow the instructions found there to install:
sudo add-apt-repository ppa:blue-shell/firefox-kde sudo apt-get update sudo apt-get install firefox firefox-kde-support
The Firefox web browser supports a wide variety of third-party add-ons, extensions, and plug-ins. They are referred to as "plug-ins" in this guide (the original term) but many are found and configured under the "extensions" or "add-ons" tabs in Firefox (once they are installed).
- Firefox -> Tools -> Add-ons -> Extensions (or Plug-ins)
Adblock Plus plug-in (block ads in a web page)
Adblock Plus blocks ads that appear in web pages. It is an important tool to limit tracking and undesirable website elements, as well. You can subscribe to a free filter service, and can add to the block list individual ads and website elements with a single click.
sudo apt-get install xul-ext-adblock-plus
- You can also add this extension from Firefox -> Tools -> Add-ons -> Get Add-ons -> Search All Add-ons -> AdBlock Plus. (This method will also ensure that automatic updates are installed by Firefox.)
- Recent versions of Adblock Plus allow the display of a large number of "partner" ads unless you disable this undesirable behavior:
- Firefox -> Tools -> Add-ons -> Adblock Plus -> Preferences -> Filter preferences... -> Allow some non-intrusive advertising (unticked)
Because Adblock Plus appears to now be creating holes in its own blocking service, it is probably worthwhile to stop automatic updates and only update Adblock Plus selectively (in case the developers in the future decide to create even more holes in the plug-in's blocking capability without the corresponding option to disable the behavior).
NoScript plug-in (controls scripts)
The NoScript plugin is considered one of the most important security measures for browsing the Internet. Most viruses and trojans gain access to computers from the Internet through scripts. This plugin allows you to choose which scripts to allow and blocks the rest.
- Add this extension from Firefox -> Tools -> Add-ons -> Get Add-ons -> Search All Add-ons -> NoScript. (This method will also ensure that automatic updates are installed by Firefox.)
- NoScript has a long of websites on its "whitelist." It is important to review this list and remove the websites for which you don't wish to automatically allow scripts (I remove them all).
- Firefox -> Tools -> Add-ons -> NoScript -> Preferences -> Whitelist
- A large number of websites use multiple locations/URLs to assemble their webpage content, a process which is blocked by NoScript's ABE (Application Boundaries Enforcer) function. I have found it necessary to disable ABE in order for most of my websites to function correctly.
- Firefox -> Tools -> Add-ons -> NoScript -> Preferences -> Advanced -> ABE -> Enable ABE (unticked)
- Many websites now use aggressive pop-ups to place advertising in front of the actual content. While NoScript can block these ads, there will be a "placeholder" still blocking the content unless you turn off the placeholders:
- Firefox -> Tools -> Add-ons -> NoScript -> Preferences -> Embeddings -> Show placeholder icon (unticked)
- Most websites use scripting extensively these days, so that you may need to "Allow" a website in NoScript. To block the individual undesirable elements of the website, use AdBlock Plus.
Bookmark Favicon Changer plug-in
In the newest versions of Firefox, there are some bugs regarding the Favicons (the small icons that appear in the address bar) and the Bookmark icons. This plug-in will restore the icons that get erased (leaving a blank dotted box) or allow you to choose your own Favicons / Bookmark icons.
- Add this extension from Firefox -> Tools -> Add-ons -> Get Add-ons -> Search All Add-ons -> Bookmark Favicon. (This method will also ensure that automatic updates are installed by Firefox.)
RefreshBlocker plug-in (prevents redirects)
RefreshBlocker allows the user to decide which websites (and pages) will be allowed to redirect (based on META tags within the webpage). Although Firefox (as of version 3.5) blocks all directs by default, the behavior is not customizable; it is therefore preferable to turn off the Firefox redirect control and use RefreshBlocker instead.
- Add this extension from Firefox -> Tools -> Add-ons -> Get Add-ons -> Search All Add-ons -> RefreshBlocker. (This method will also ensure that automatic updates are installed by Firefox.)
- Turn off the Firefox automatic redirect blocker:
- Firefox -> Enter about:config in the browser location bar -> right-click on "accessibility:blockautorefresh" -> Toggle to change the value from true to false
Video DownloadHelper plug-in for Firefox
The Video DownloadHelper plugin allows the download of videos (including Flash videos) from sites like YouTube.
- You can add this extension from Firefox -> Tools -> Add-ons -> Get Add-ons -> Search All Add-ons -> Video DownloadHelper. (This method will also ensure that automatic updates are installed by Firefox.)
Hide Tab Bar With One Tab plug-in
In Firefox v. 23 and later, the ability to hide tabs has been disabled. This plugin restores the ability to hide tabs if only one tab is open, restoring the function to hide tabs during normal browsing.
- You can add this extension from Firefox -> Tools -> Add-ons -> Get Add-ons -> Search All Add-ons -> Hide Tab Bar With One Tab. (This method will also ensure that automatic updates are installed by Firefox.)
User Agent Switcher plug-in for Firefox
The User Agent Switcher plugin allows a browser to masquerade as another browser, allowing browser-specific content to be displayed (most of the time). In the past there were a few old web apps that ran only on IE (and if one is encountered this plug-in may still be useful). Now that Firefox is the world's leading web browser, however, this plug-in should no longer be necessary for the average user.
- A user agent string also identifies your OS. Users of an uncommonly used (and easily identifiable) OS may wish to protect their privacy and not identify their OS correctly; for these users, User Agent Switcher is valuable for privacy reasons. Some users, for example, may wish to identify their very specialised OS as Debian or Ubuntu instead.
- You can add this extension from Firefox -> Tools -> Add-ons -> Get Add-ons -> Search All Add-ons -> User Agent Switcher. (This method will also ensure that automatic updates are installed by Firefox.)
- To use this add-on, the settings for Firefox must be changed prior to usage:
- Firefox -> about:config -> Search: useragent -> general.useragent.enable_overrides -> Toggle (so that the value is true) -> Restart Firefox
- A disadvantage of the User Agent Switcher is that it allows Firefox to revert to the default user agent string at each restart, so that it must be re-engaged each time. An alternate method to change the default Firefox user agent string is directly through the about:config settings (also see this blog post):
- Firefox -> about:config -> Search: useragent -> general.useragent.enable_overrides -> Toggle (so that the value is true) -> <right-click> -> New -> String -> Enter the preference name: general.useragent.override -> OK -> general.useragent.override: Mozilla/5.0 (X11; Kubuntu; Linux x86_64; rv:26.0) Gecko/20100101 Firefox/26.0 -> OK -> Restart Firefox
- The default user agent string for Kubuntu actually reflects Ubuntu as the OS (so that online OS usage statistics incorrectly count Kubuntu as Ubuntu). If you wish Kubuntu usage to be accurately counted, it is helpful to change your user agent string permanently.
Lightbeam (website crosslink visualization)
Lightbeam is a Firefox plug-in that is able to display the links on a website (to which you are connected) while browsing, giving you an indication of who can see your browsing habits at that moment.
- You can add this extension from Firefox -> Tools -> Add-ons -> Get Add-ons -> Search All Add-ons -> Lightbeam. (This method will also ensure that automatic updates are installed by Firefox.)
Unplug Download Management
The UnPlug add-on lets you save video and audio which is embedded on a webpage.
- You can add this extension from Firefox -> Tools -> Add-ons -> Get Add-ons -> Browse All Add-ons. (This method will also ensure that automatic updates are installed by Firefox.)
Lucifox (eBook reader extension)
Lucifox (Lucidor for Firefox) enables e-books to be read and e-book catalogs to be browsed in a Firefox window.
- To install, go to the website and click "Download Now."
Adobe Acrobat Reader for Firefox Plug-in
- Read Add Extra Kubuntu Repositories and enable the Quantal partner repository:
deb http://archive.canonical.com/ubuntu Quantal partner
- then install Adobe Reader:
sudo apt-get install acroread
Adobe Flash Player for Firefox Plug-in
To install the official Adobe Flash plugin (Flash 10) for Firefox:
sudo apt-get install adobe-flashplugin
Gnash Plug-in (Open source Flash Player replacement)
Gnash is available in a 64-bit version as well as a 32-bit version. It is the open source replacement for Adobe Flashplayer.
sudo apt-get install gnash
After installing, change your web browser's Preferences -> Applications so that SWF and SPL files use Gnash.
Java Runtime Environment (JRE) for Firefox plug-in
- The IcedTea Plugin allows browsers to execute Java applets. The default icedtea-plugin package points to the icedtea-6-plugin package. Install:
sudo apt-get install icedtea-plugin
- Alternatively, install the IcedTea Plugin for version 7:
sudo apt-get install icedtea-7-plugin
- This package may need to be installed to run Java in Firefox, even if the Java Runtime Environment (JRE) is installed using kubuntu-restricted-extras, when installing OpenOffice, or installing the Java enviroment manually.
sudo apt-get install default-jre icedtea-plugin
Note: You must accept the license to use this product.
Kaffeine Plug-in for Firefox
This package also installs the Kaffeine player.
sudo apt-get install kaffeine-mozilla
MPlayer plug-in for Firefox
Gecko-mediaplayer has replaced the Mplayer plugin. This package also installs gnome-mplayer.
sudo apt-get install gecko-mediaplayer
VLC plug-in for Firefox
This package also installs the VLC player.
sudo apt-get install mozilla-plugin-vlc
Helix player plug-in for Firefox
This package also installs the Helix player, which is the open source player that plays Real Player content in Linux.
sudo apt-get install mozilla-helix-player
Moonlight plugin for Firefox
Moonlight is part of the Novell Mono project that is an open source implementation of Silverlight (the Microsoft multimedia presentation platform). It is based on FFMpeg. It is made to work best with the Firefox 3 web browser, as a plugin (but also works with other mozilla browsers). Version 2.3 is available as a plugin for mozilla-based browsers:
sudo apt-get install moonlight-plugin-mozilla
- The stable version 2.4 is available here. The Moonlight 3.99 plugin (compatible with most Silverlight 3/4 content) is here.
- Netflix under Moonlight
- Netflix streaming requires both the capabilities of Silverlight 2.0 and Digital Rights Management modules. Although the current version of Moonlight 2.0 will run most Silverlight content (including Netflix content), Netflix has not yet released Digital Rights Management modules for Linux. Please contact Netflix directly for further information or sign a petition.
FireFTP for Firefox
FireFTP is a Firefox extension for FTP transfers.
Turn off browser bar drop-down list in Firefox
This is the most frequently asked problem regarding Firefox. To turn off the location browser bar drop-down list (and therefore not show your browsing history):
- Firefox -> about:config (in the location browser bar) -> browser.urlbar.maxRichResults -> right-click -> Modify -> set value to 0
Turn off SSL certificate name in address bar
In newer versions of firefox, the validity of the SSL certificate associated with a website is displayed as a color-coded background to the Favicon (the small icon displayed in the address bar). However, Firefox currently also displays the name of the site issuing the SSL certificate, which can be annoying, since for most sites this is a duplicate of the domain name (which then gets displayed twice in the address bar). To turn off this behavior:
- Firefox -> about:config (in the location browser bar) -> browser.identity.ssl_domain_display -> right-click -> Modify -> set value to 0
View Firefox cache
In a new window/tab, enter about:cache in the Firefox address bar. You can view and save individual elements (from all open windows/tabs) in the cache from there.
- Due to trademark restrictions of Mozilla products, the Debian project has created versions of the (otherwise free) software that has been stripped of the non-free trademarks. See here and the Debian wiki for more information. To install them, use a package manager to add the Debian repository for your country ( e.g. deb http://ftp.us.debian.org/debian unstable main ) temporarily while installing the software. Then install the software package using the package manager or from the command line:
- IceWeasel replaces the Firefox web browser (sudo apt-get install -t iceweasel).
- IceDove replaces the Thunderbird email, newsreader, and calendaring client (sudo apt-get install -t icedove).
- IceOwl replaces the Sunbird standalone calendaring client (sudo apt-get install -t iceowl).
- After installation of the individual package, it is best to disable the Debian repository so it does not interfere with the (K)Ubuntu repositories.
- A user that is interested in the philosophy of free software that Iceweasel symbolises may wish to consider a full Debian OS installation (of which (K)Ubuntu is a fork) instead of (K)Ubuntu.
The GNU project also maintains a version of Mozilla Firefox that is free of trademarks and branding, called GNUZilla IceCat. .deb packages for (K)Ubuntu can be downloaded and installed through the GNUzilla PPA repositories.
Opera is a proprietary browser and internet suite (currently free on PCs) also used in some mobile devices and gaming consoles. It includes email, an address book, IRC chat, integrated BitTorrent, and webfeeds. A limited number of plugins are also available. Download from the website and follow the instructions or install from the Opera repository:
echo "deb http://deb.opera.com/opera/ stable non-free" | sudo tee /etc/apt/sources.list.d/opera.list wget -O - http://deb.opera.com/archive.key | sudo apt-key add - sudo apt-get install opera
Chromium is the open source browser on which Google Chrome is based. It does not include the undesirable user tracking mechanisms of Google Chrome or the Google logos (and is therefore recommended by many users instead of Chrome).
sudo apt-get install chromium-browser
Google Chrome is Google's proprietary web browser. Based on the open-source Chromium browser, Google adds the Google name and logo, an auto-updater system called GoogleUpdate, RLZ (a user-tracking mechanism), and other Google add-ons. To use this instead of Chromium, download and install the .deb package here.
KGet is a versatile and user-friendly download manager.
MultiGet is a GTK-based free-standing download manager utility.
sudo apt-get install multiget
sudo apt-get install pan
- K menu -> Office -> Kontact Personal Information Manager
- K menu -> Internet -> KMail
Kontact includes email, an address book, a calendar, reminders, pop-up notes, a link to the Akregator News/RSS reader, time-tracking, and more.
To change view mode or aggregation mode (grouping) of the message list pane, use the icons to the right of the search pane. (Configuration of this doesn't seem to be available from the settings menus.)
PGP and Kmail
- Kmail -> Configure Kmail -> Security -> Crypto Backends
Mozilla Thunderbird is a licensed and trademarked free open-source email client that is compatible with Firefox. Thunderbird works with free Gmail and Yahoo Mail accounts (using Imap). Install:
sudo apt-get install thunderbird
Lightning calendar extension
sudo apt-get install xul-ext-lightning
Enigmail is an add-on to Thunderbird that allows you to easily encrypt your email using OpenPGP, which is included in the kernel by default. It also allows you to create and manage the encryption keys. Install:
sudo apt-get install enigmail
- Also see these tips for instructions on setting up e-mail with PGP encryption.
Miniminize to System Tray
MinimizeToTray revived is a valuable plugin/add-on/extension, IMO. It allows Thunderbird to be minimized to the System Tray instead of to the Taskbar. This allows Thunderbird to run discreetly in the background, checking for new mail and calendar events (e.g. through the Lightning extension). The same plugin/add-on/extension also is available for Firefox. Install:
- Thunderbird -> Tools -> Add-ons -> Get Add-ons -> Browse all add-ons (takes you to an external webpage) -> search for add-ons: MinimizeToTray revived -> + Add to Thunderbird -> Install Now -> Restart Thunderbird
New Mail Icon for Thunderbird
New Mail Icon is an experimental tray add-on which notifies you of new mail. (Note: If you leave Thunderbird running minimized to the System Tray (with the MinimizeToTray add-on, for example), it has a built-in "new message" notifier already, so that this add-on would not be necessary in such a situation.) Download from the website. Install:
- Thunderbird -> Tools -> Add-ons -> Install -> select downloaded file
Evolution is the default Gnome-based email client used in Ubuntu. Installing it will also install many Gnome components.
sudo apt-get install evolution
FetchYahoo is a Perl script to fetch mail from a free Yahoo mail account and spool it locally so that an email client like Thunderbird can access it with POP3. For more info see the Ubuntu Community documentation. Install:
sudo apt-get install fetchyahoo
Install java and in order to use the internal browser, install the packages xulrunner and firefox:
sudo apt-get install sun-java6-jre firefox xulrunner
Change to your "opt" directory:
Download the zip-archive into your opt directory:
sudo wget http://downloads.sourceforge.net/rssowl/rssowl-2.0.6.linux.zip
Extract the archive and remove the extracted file:
sudo unzip ./rssowl-2.0.6.linux.zip && sudo rm ./rssowl-2.0.6.linux.zip
Make a startscript:
sudo kate /usr/bin/runRSSOwl.sh
add the following lines to your startscript file /usr/bin/runRSSOwl.sh and save it afterwards.
#!/bin/bash cd /opt/rssowl ./RSSOwl
Make the startscript executable:
sudo chmod u+x /usr/bin/runRSSOwl.sh
To start RSSOwl:
Kopete is the default Instant Messenger application for KDE/Kubuntu. Webcam video and voice capability is incorporated. You can access multiple services with it. You can access it by:
- K Menu -> Applications -> Internet -> Kopete Instant Messenger.
Plugins for Kopete
Kopete includes a number of default plugins:
- Kopete -> Settings -> Configure -> Plugins
- A language Translator plugin that can be used with Google or BabelFish is available (but is no longer functional since the closure of both the Google Translate API and BabelFish in 2012).
- An encryption plugin (using Off-The-Record encryption) is available.
- OpenPGP for Kopete is also available by installing the package kopete-cryptography:
sudo apt-get install kopete-cryptography
Additional styles for Kopete are available from KDE-look. Install from:
- Kopete -> Settings -> Configure -> Chat Window -> Style -> Get New...
GoogleTalk on Kopete
Facebook Chat on Kopete
- See this Kubuntu forums thread for info on setting up Kopete with Facebook chat.
Konversation (IRC client)
Konversation is no longer the default Internet Relay Chat (IRC) client in Kubuntu, but is highly recommended nevertheless. It functions similar to the venerable mIRC. Make sure you have ports 6667-6670 open in your firewall to use IRC (and ports 1024-1028 open to use DCC). "A little less action and a little more Konversation." -- Elvis. Install:
sudo apt-get install konversation
- K menu -> Internet -> Konversation
- Konversation can be used directly with a proxy. For example, if you are using a Socks5 proxy on port 9050:
- Konversation -> Settings -> Configure Konversation... -> Behavior: Connection -> Proxy (ticked) -> Type: Socks v5 -> Address: 127.0.0.1 (or localhost) -> Port: 9050
Quassel (IRC client)
Quassel is a cross-platform IRC client currently that is included as the default Kubuntu/KDE client. Based on the Qt platform, there is no DCC implementation (which makes this client limited in usefulness). Try Konversation for more features.
- Quassel can be used directly with a proxy on a per-server basis. For example, if you are using a Socks5 proxy on port 9050:
- Quassel -> File -> Networks -> Configure Networks... -> Servers: irc.ubuntu.com:8001 -> Edit -> Advanced -> Use a Proxy (ticked) -> Proxy Type: Socks 5 -> Proxy Host: 127.0.0.1 (or localhost) -> Port: 9050
XChat (IRC client)
XChat is a cross-platform IRC client that allows DCC downloads and scripts. Install:
sudo apt-get install xchat
- or a Gnome-integrated version:
sudo apt-get install xchat-gnome
Pidgin is an open source IM application. It is the default in the Ubuntu (Gnome) desktop, but will work in Kubuntu (KDE). You can access multiple services with it.
sudo apt-get install pidgin
aMSN is an MSN Messenger utility that functions like the original client. Unlike Kopete, it is not made for the KDE desktop (but can be installed nevertheless). Install it:
sudo apt-get install amsn
To enable Drag-and-Drop capabilities to aMSN for easy file transfer see Ubuntu Geek.
sudo apt-get install emesene
sudo apt-get install kmess
Widget icon (upper right corner of desktop) -> Add widgets ... -> Microblogging
sudo apt-get install choqok
- Notifications (popups/sounds) for incoming messages can be set:
- K Menu -> System -> System Settings -> Notifications -> Event Source: Choqok -> New Post Arrived -> Play a sound (ticked)
- When Twitter switched off API 1.0 on 11 June 2013, the tweets went dark for Choqok users as the application had not been updated in time to support API 1.1. This was due to the original developer not having time to maintain Choqok himself. On appeal to the Linux community, another developer stepped in and developed Choqok > 1.3.1 (which supports the API 1.1).
- For users of Kubuntu Precise Pangolin 12.04 or later (> KDE 4.10), the updated program (or patch) is available at Launchpad. Download and run the version for your OS (32-bit i386 or 64-bit amd64). Either the Raring or Saucy version version will work for Quantal (after updating packages, including from KDE 4.9 to KDE 4.10).
FileZilla is the ubiquitous free open-source FTP client and server for all platforms.
sudo apt-get install filezilla
Filesharing / P2P
Do not share copyrighted material or content that is otherwise illegal to share.
- K menu -> Internet -> KTorrent
Be sure to have your firewall ports open (by default 6881 and 4444).
- It is possible to use proxies with KTorrent. For example, if you have a tracker proxy at 127.0.0.1:8118 and a socks proxy at 127.0.0.1:9050, then set KTorrent to use these proxies:
- KTorrent -> Settings -> Configure KTorrent... -> Proxy
- -> HTTP:Proxy: 127.0.0.1 -> Port: 8118
- -> SOCKS: Use a SOCKS proxy server: (ticked) -> Server: 127.0.0.1 -> Port: 9050 -> Version 5 (assuming you are using socks5)
- It is possible to use encryption with KTorrent:
- KTorrent -> Settings -> Configure KTorrent... -> BitTorrent -> Encryption -> Use protocol encryption
In an era of increasing censorship, spying, and surveillance using Deep Packet Inspection, encryption has become an essential componenet of data transfer.
- KTorrent -> Plugins -> IP Filter (ticked) -> Settings -> Configure KTorrent... -> IP Filter -> Use PeerGuardian filter (ticked) -> Download/Convert
This service attempts to monitor and filter IP addresses known for censorship, spying, or provision of false or malicious data to this type of Internet service.
- Some older routers only allow 20 simultaneous connections or they will continually freeze (as their connection-table cache becomes full). If this occurs, decrease the maximum number of connections to 20:
- KTorrent -> Settings -> Configure KTorrent... -> Network -> Advanced: Maximum number of connection setups: 20
Set Firefox to use KTorrent for magnet links
Firefox is very ticklish about this setting, so follow the instructions very carefully.
- Open a window which has a magnet link on it. Click on the magnet link, and the error "Firefox doesn't know how to open this address, because the protocol (magnet) isn't associated with any program" usually appears.
- Open a new tab (NOT a new window) and edit the configuration settings by typing about:config in the address bar of the newly-opened tab. Then add the network.protocol-handler.expose.magnet setting and set it to false:
- Firefox -> about:config -> Search: network.protocol-handler.expose -> <Right-click> on the main window
- -> New -> Boolean -> Enter the preference name: network.protocol-handler.expose.magnet -> Ok
- -> False -> Ok
- DO NOT CLOSE the about:config tab until this step is complete! While the about:config tab remains open, go to the tab with your magnet link available. Click on the magnet link. A dialog box should appear to choose the application.
- Firefox -> Launch Application: Choose an Application: Choose... -> File system: /usr/bin/ktorrent
- -> Remember my choice for magnet links (ticked) -> Ok
- Now whenever you click on a magnet link in Firefox, it should be added automatically to KTorrent and will be found in the KTorrent -> Magnet section. If a different downloading program is later desired for use with magnets, the setting in Firefox can subsequently be changed:
- Firefox -> Preferences -> Applications -> magnet -> (dropdown box)
- Note: Magnet links will not work with KTorrent versions prior to 4.3 (and libktorrent 1.3). Download and install the current KTorrent / libktorrent versions from source code according to instructions here or install the Debian (.deb) packages found here.
Azureus is a Java-based BitTorrent client.
sudo apt-get install azureus
QBitTorrent is a PyQT-based BitTorrent Client that is based on the uTorrent model.
sudo apt-get install qBittorrent
Transmission (BitTorrent Client)
Transmission is the GTK-based default BitTorrent client in Ubuntu (Gnome). KTorrent can be used in Kubuntu.
sudo apt-get install transmission
Deluge is a GTK-based BitTorrent client, with plugins and a server package / daemon available. Install the client:
sudo apt-get install deluge-torrent
or the GTK-based interface:
sudo apt-get install deluge-gtk
- The server daemon and web interface (for server functions) can be installed:
sudo apt-get install deluged deluge-web
Bittornado (BitTorrent Client)
BitTornado is a KDE-compatible BitTorrent client. Install:
sudo apt-get bittornado bittornado-gui
Torrentflux (P2P client and server)
TorrentFlux is a PHP based BitTorrent controller that runs on a web server (using a MySQL database with the mysql-server package for server functions or the mysql-client for client functions) and uses a web interface that can be accessed remotely (e.g. http://localhost/torrentflux). This makes it ideal for seedbox purposes. It uses the BitTornado client for downloads. Install:
sudo apt-get install torrentflux
Apollon (P2P Filesharing)
Apollon is an older (now relatively obsolete) BitTorrent client that uses the Gift network (Gnutella, etc.). It uses plugins for compatibility with multiple networks. Obtain the packages from the Debian Etch archives for apollon and gift.
KMLDonkey (P2P eMule/eDonkey2000 Client)
sudo apt-get install kmldonkey mldonkey-server
Opentracker (Torrent tracker)
Opentracker is the most widely used torrent tracker software. It can be used within a private organisation or as a public service to track freely-available torrents. Download (through CVS) and installation instructions are at the website.