We're very impressed by the collective smarts of the security community and we highly recommend reading the whole list and investigating any tools you are unfamiliar with. Click any tool name for more details on that particular application, including the chance to read (and write) reviews. Many site elements are explained by tool tips if you hover your mouse over them. Enjoy!
SSH (Secure Shell) is the now ubiquitous program for logging into or executing commands on a remote machine. It provides secure encrypted communications between two untrusted hosts over an insecure network, replacing the hideously insecure telnet/rlogin/rsh alternatives. Most UNIX users run the open source OpenSSH server and client. Windows users often prefer the free PuTTY client, which is also available for many mobile devices, and WinSCP. Other Windows users prefer the nice terminal-based port of OpenSSH that comes with Cygwin. There are dozens of other free and proprietary clients to consider as well.
Read 2 reviews.
TrueCrypt is an excellent open source disk encryption system for Windows, Mac, and Linux systems. Users can encrypt entire filesystems, which are then on-the-fly encrypted/decrypted as needed without user intervention beyond initially entering their passphrase. A clever hidden volume feature allows you to hide a second layer of particularly sensitive content with plausible deniability about whether it even exists. Then if you are forced to give up your passphrase, you give them the first-level secret. That only allows them access to the innocuous material you have there, without proving that a second level key even exists.
Read 4 reviews.
Latest release: version 7.1a on Feb. 7, 2012 (3 years, 2 months ago).
PGP is the famous encryption system originally written by Phil Zimmerman which helps secure your data from eavesdroppers and other risks. GnuPG is a very well-regarded open source implementation of the PGP standard (the actual executable is named gpg). While the excellent GnuPG is always free, PGP is now owned by Symantec and costs a lot of money.
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The OpenSSL Project is a collaborative effort to develop a robust, commercial-grade, full-featured, and open source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library. Apart from being a component of many crypto programs, OpenSSL comes with a lot of command-line tools for encryption, hashing, certificate handling, and more.
Read 1 review.
Latest release: version 1.0.1g on April 7, 2014 (1 year ago).
Tor is a network of virtual tunnels designed to improve privacy and security on the Internet by routing your requests through a series of intermediate machines. It uses a normal proxy server interface so that ordinary Internet applications like web browsers and chat programs can be configured to use it. In addition to helping preserve users' anonymity, Tor can help evade firewall restrictions. Tor's hidden services allow users publish web sites and other services without revealing their identity or location. For a free cross-platform GUI, users recommend Vidalia. Remember that Tor exit nodes are sometimes run by malicious parties and can sniff your traffic, so avoid authenticating using insecure network protocols (such as non-SSL web sites and mail servers). That is always dangerous, but particularly bad when routing through Tor.
Read 1 review.
Latest release: version 0.2.4.21 on Feb. 28, 2014 (1 year, 1 month ago).
OpenVPN is an open-source SSL VPN package which can accommodate a wide range of configurations, including remote access, site-to-site VPNs, WiFi security, and enterprise-scale remote access solutions with load balancing, failover, and fine-grained access-controls. OpenVPN implements OSI layer 2 or 3 secure network extension using the industry standard SSL/TLS protocol, supports flexible client authentication methods based on certificates, smart cards, and/or 2-factor authentication, and allows user or group-specific access control policies using firewall rules applied to the VPN virtual interface. OpenVPN uses OpenSSL as its primary cryptographic library.
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Latest release: version 2.3.4 on May 2, 2014 (11 months, 3 weeks ago).
KeePass is a password manager. It stores many passwords which are unlocked by one master password. The idea is to only have to remember one high-quality password, and still be able to use unique passwords for various accounts. It has a feature to automatically fill in passwords in web forms.
Read 3 reviews.
Latest release: version 1.27 on April 6, 2014 (1 year ago).
The stunnel program is designed to work as an SSL encryption wrapper between remote client and local (inetd-startable) or remote servers. It can be used to add SSL functionality to commonly used inetd daemons like POP2, POP3, and IMAP servers without any changes in the programs' code. It will negotiate an SSL connection using the OpenSSL or SSLeay libraries.
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Latest release: version 5.01 on April 8, 2014 (1 year ago).