Linux Server Security, Second Edition

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Secure Shell Background and Basic Use

|

127

There are many other options in addition to these; some of them are covered in

“Intermediate and Advanced SSH” (later in this chapter). Refer to the ssh(1)

manpage for a complete list.

Configuring and Running sshd, the Secure Shell Daemon

Editing ssh_config is sufficient if the hosts you connect to are administered by other

people. But we haven’t yet talked about configuring your own host to accept ssh con-

nections.

Like the ssh client, sshd’s default behavior is configured in a single file, sshd_config,

that resides either in /etc or wherever else you specified in SSH’s configuration direc-

tory. As with the ssh client, settings in its configuration file are overridden by com-

mand-line arguments. Unlike ssh, however, there are no configuration files for the

daemon in individual users’ home directories; ordinary users can’t dictate how the

daemon behaves.

Table 4-2 lists just a few of the things that can be set in sshd_config.

ForwardX11

Yes, No (Default=No) Whether to redirect X connections over the

encrypted tunnel and to set

DISPLAY vari-

able accordingly. Very handy feature!

PasswordAuthentication

Yes, No (Default=Yes) Whether to attempt (encrypted) Unix pass-

word authentication in addition to or instead

of trying RSA/DSA.

Table 4-2. Some sshd_config ...