Linvpn is a secure socket layer for pppd. It allows creation of virtual private networks by using an IP routing system between PPP network interfaces. Cryptography is done by libgcrypt's 3DES or blowfish, and Initialization Vector (IV) is changed in each packet transmission. As linvpn works as client and server, and communication is a single TCP connection, it allows creation of secure tunnels even in complex network layouts, when one or both endpoints are behind a firewall or NAT, with or without dynamic IP addresses.
Cyclone is a low-level network toolkit that provides support for HTTP 1.1 in an API very similar to the one implemented by the Tornado Web server. It has localization based on gettext with pluralization support, native support for XMLRPC and JSONRPC, native support for WebSockets (drafts 75 and 76), decent support for sending plain text or HTML email with TLS and attachments, built-in support for Redis, and support for HTTP authentication.