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 client applications:
ssh — A secure remote console access
scp — A secure remote copy command.
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.