rrs is a reverse (connecting) remote shell.
Instead of listening, it will connect out to rrs
in listen mode. The listener will accept the
connection and receive a shell from the remote
host. rrs features full pseudo-TTY support, full
OpenSSL support (client/server authentication and
choice of cipher suites), Twofish encryption, a
simple XOR cipher, plain-text sessions, peer-side
session snooping, a daemon option, and
reconnection features. It is known to compile and
run under Linux, FreeBSD, NetBSD, OpenBSD, and QNX.