Description-en: program for managing a Netfilter firewall
The Uncomplicated FireWall is a front-end for iptables, to make managing a Netfilter firewall easier. It provides a command line interface with syntax similar to OpenBSD's Packet Filter. It is particularly well-suited as a host-based firewall.

Description-en: decentralized instant messenger built on top of the Tor Network
TorChat is a peer to peer instant messenger with a completely decentralized
design, built on top of Tor's location hidden services, providing strong
anonymity while being very easy to use
.
Top most relevant feature TorChat claims, above from text messaging and file
sending, rest on the difficulty someone would experiment trying to find out
where you are communicating from
.
In the condition someone might be observing you and sniff your internet traffic
connection, the person will find highly difficult to find out:
- Where your contacts are located
- To whom you are sending or receiving from
- What you send or receive, as everything is end-to-end encrypted
Homepage: http://code.google.com/p/torchat

Tribler is a social community that facilitates filesharing through a peer-to-peer (p2p) network. A p2p network is different from a centralised service, where every user downloads his files from one central server. With p2p, the user/downloader is also an uploader to another user. This way, there is no central computer required that provides every file to all users.

Secure video calls, conferencing, chat, desktop sharing, file transfer, support for your favorite OS, and IM network. All this, and more, in Jitsi - the most complete and advanced open source communicator.

Features
Security

Encrypted password storage
Password protection with a master password
Encrypted Instant Messaging with Off-the-Record Messaging (OTR)
Call encryption with SRTP and ZRTP for XMPP and SIP
Call encryption with SRTP and SDES for SIP
DNSSEC support
TLS support and certificate-based client authentication for SIP
Miscellaneous

On-line provisioning
Provisioning server discovery via DHCP and mDNS (Bonjour)
IPv6 fully supported by SIP and XMPP
Call history
Missed call notifications
Systray notifications (using Swing, Growl or libnotify)
Drag and drop support for file transfer
Integration with Microsoft Outlook and Apple Address Book
Support for LDAP directories
Support for Google Contacts
SIP specific

On-line contact list storage with XCAP
Secure signalling with TLS
DTMF (SIP INFO, RTP RFC 2833/4733, inband)
Message Waiting Indication (RFC 3842)
XMPP Specific

DTMF (RTP RFC 2833/4733, inband)

If you want to turn on 2-step verification and own a smartphone, we recommend you use the Google Authenticator app -- a mobile application available on Android devices, iPhones, and BlackBerry devices -- to generate verification codes. The application doesn't require an Internet connection, mobile service, or a data plan to generate verification codes.

PeerGuardian helps protect your privacy by blocking many ranges of aggressive IPs while you use P2P.

moblock-deb provides packages related to IP blocking software, similar to PeerGuardian: In order to protect your privacy internet traffic is blocked based on large lists of IP address ranges. The packages are PeerGuardian Linux (pgl), and its precessors moblock, blockcontrol and mobloquer.

RetroShare is a Open Source cross-platform, private and secure decentralised communication platform.
It lets you to securely chat and share files with your friends and family, using a web-of-trust to authenticate peers and OpenSSL to encrypt all communication.
RetroShare provides filesharing, chat, messages, forums and channels

RetroShare is the next generation sharing network, which provides:

Reliable Identification and Authentication of your friends.
Plus an Introduction Scheme which connects you to the friends of your friends, and facilitates network growth.
Encrypted Communication, ensuring all shared information is known only to you and your peers.
A Communication Platform which can potentially support services such as Secure Email, File Sharing, Streaming, Video or Voice over IP, Photos, Wall and Messaging
A Decentralised Social Sharing Network designed **For the People** with no dependancies on any corporate system or central servers.

You want to chat and share files securely with your friends
Only your friends will be able to see and download files that you share.
RetroShare is serverless, which means - unlike other messengers, you don't* need to register, complete annoying registration forms and receive tons of ads. Sending a key to your friend by e-mail is enough to set up your own IM network. This also means no IM spam, because people you didn't invite absolutely cannot connect.
You can also use your favorite nick name either: no need to use cryptic names like "john.smith148@something.com" just because someone (whom you don't even know) snapped your favorite nick before you.
RetroShare is encrypted, meaning high privacy: nobody, including your
ISP, can see what files you're sharing.

You need secure instant messaging and files exchange for a small workgroup.
You need to chat securely and exchange files with other colleagues at work, but do not trust your data to a public chat network like Live or Google Chat ? Don't want a hassle of installing and maintaining your own chat server either ? Use RetroShare instead:

RetroShare is serverless , which means that no server, ever, gets to see your data. Any IM server, no matter how secure, poses a risk of data leak because of hacker's attack. Retroshare completely eliminates this security risk associated with the IM server, without any added costs.
RetroShare encrypts all connections, which means every bit of data is encrypted end-to-end. Unlike other products using self-made weak encryption, RetroShare uses a special version of industry standard Openssl library, trusted by banks and other organizations.
Absolutely no vendor lock-in: you own your RetroShare network. There is no 3rd party vendor whom you have to pay, or who may go out of business and force you to migrate to another product.

Why DNSCrypt is so significant

In the same way the SSL turns HTTP web traffic into HTTPS encrypted Web traffic, DNSCrypt turns regular DNS traffic into encrypted DNS traffic that is secure from eavesdropping and man-in-the-middle attacks. It doesn't require any changes to domain names or how they work, it simply provides a method for securely encrypting communication between our customers and our DNS servers in our data centers.

DNSCrypt has the potential to be the most impactful advancement in Internet security since SSL, significantly improving every single Internet user's online security and privacy.

Here are the correct steps:
gedit /etc/init.d/dnscrypt.sh
Paste:

### BEGIN INIT INFO
# Provides: dnscrypt
# Required-Start: $all
# Required-Stop: $all
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: DNSCrypt for OpenDNS
# Description: Launch the dnscrypt to communicate with OpenDNS
### END INIT INFO

/usr/sbin/dnscrypt-proxy --daemonize

Save then:
cd /etc/init.d/
chmod +x dnscrypt.sh
update-rc.d dnscrypt.sh defaults
update-rc.d dnscrypt.sh enable

Configure your connection manager to use 127.0.0.1 as DNS and now it should work