As the size and popularity of the Internet has grown, so has the
threat of communication interception. Over the years, tools have
been developed to encrypt communications as they are transferred
over the network.
Red Hat Enterprise Linux ships with two basic tools that use
high-level, public-key-cryptography-based encryption algorithms to
protect information as it travels over the network.
OpenSSH — A free implementation of
the SSH protocol for encrypting network communication.
Gnu Privacy Guard (GPG) — A free
implementation of the PGP (Pretty Good Privacy) encryption
application for encrypting data.
OpenSSH is a safer way to access a remote machine and replaces
older, unencrypted services like telnet
and rsh. OpenSSH includes a network
service called sshd and three command line
ssh — A secure remote console
scp — A secure remote copy
sftp — A secure pseudo-ftp client
that allows interactive file transfer sessions.
It is highly recommended that any remote communication with
Linux systems occur using the SSH protocol. For more information
about OpenSSH, refer to the chapter titled OpenSSH in the Red Hat
Enterprise Linux System Administration Guide. For more
information about the SSH Protocol, refer to the chapter titled
SSH Protocol in the Red Hat Enterprise Linux Reference Guide.
Although the sshd service is inherently
secure, the service must be kept up-to-date
to prevent security threats. Refer to Chapter 3 Security Updates
for more information about this issue.
GPG is one way to ensure private email communication. It can be
used both to email sensitive data over public networks and to
protect sensitive data on hard drives.
For more information about using GPG, refer to the appendix
titled Getting Started with Gnu Privacy
Guard in the Red Hat Enterprise Linux Step
By Step Guide.