Linux in a Nutshell, 6th Edition

Name

sshd

Synopsis

sshd [options]

TCP/IP command. Server for the ssh program, providing a secure remote-login and remote-execution facility equivalent to rlogin and rsh. Normally started at boot, sshd listens for incoming connections, forking a new daemon when one is detected. The forked daemon handles authentication, command execution, and encryption. Most implementations of sshd support both SSH protocols 1 and 2. The following options are those used by OpenSSH, OpenBSD’s Secure Shell implementation.

Options

−4

Use only IPv4 addresses.

−6

Use only IPv6 addresses.

-b bits

Use the specified number of bits in the server key. Default is 768.

-d

Run sshd in the foreground and send verbose debug information to the system log. Process only one connection. Use the specified number of bits in the server key. This option may be specified from one to three times. Each additional -d increases the level of information sent to the system log.

-D

Do not detach from the foreground process.

-e

Send output to standard error instead of the system log.

-f file

Read configuration information from file instead of the default configuration file /etc/ssh/sshd_config.

-g seconds

Set the grace time a client has to authenticate itself before the server disconnects and exits. The default is 600 seconds. A value of 0 means there is no limit.

-h keyfile

Read the host’s cryptographic key from the specified keyfile instead of from the default file /etc/ssh/ssh_host_key for SSH protocol 1, and the default files /etc/ssh/ssh_host_rsa_key ...