MatrixSSL is an embedded SSL and TLS implementation designed for small footprint devices and applications requiring low overhead per connection. The library is less than 50Kb on disk with cipher suites. It includes client and server support through TLS 1.2, mutual authentication, session resumption, and implementations of RSA, ECC, AES, 3DES, ARC4, SHA2, SHA1, and MD5. The source is well documented and contains portability layers for additional operating systems, cipher suites, and cryptography providers.
INDI is an instrument-neutral distributed interface control protocol that aims to provide backend driver support and automation for a wide range of astronomical devices (telescopes, focusers, CCDs, etc.). Current supported devices include many telescopes, CCDs, filter wheels, focusers, and video cams. INDI is used in popular astronomy suites like Xephem, KStars, DCD, and Cartes Du Ciel.
msmtp is an SMTP client with a sendmail compatible interface. It can be used with Mutt and other MUAs. It forwards messages to an SMTP server which does the delivery. Features include various SMTP AUTH methods, TLS/SSL-encrypted connections (including support for client certificates), support for multiple accounts, DSN, and IPv6 support.
Ctpp is the C99-compatible C preprocessor of the Ctalk language, which provides object oriented extensions for C. The preprocessor is compatible with GNU cpp and provides extensions like macro expansion in warning and error messages, saving expanded macros to files, and built-in symbol definition for many command line options. You can download the preprocessor separately while Ctalk is between versions for development.
DISLIN is a high-level, easy-to-use plotting library for displaying data as curves, bar graphs, pie charts, 3D-colour plots, surfaces, contours, and maps. Several output formats are supported, such as X11, VGA, PostScript, PDF, CGM, HPGL, TIFF, and PNG. Plotting extensions for the interpreter-based languages Perl, Python, and Java are also supported for most operating systems.
Libpwmd provides an API for applications needing to communicate with PWMD (Password Manager Daemon). It is thread safe. It can connect to a remote pwmd server over an SSH channel or via TLS using a client certificate as authentication. It can use a pinentry program to prompt for a passphrase when needed. It supports secure memory management. It includes a command line client with a shell-like interface that can also read a Pwmd protocol command from standard input.
rsync is a replacement for rcp (and scp) that has many more features. It uses the "rsync algorithm" which provides a very fast method for remote files into sync. It does this by sending just the differences in the files across the link, without requiring that both sets of files are present at one of the ends of the link beforehand.