5. Configure OpenSSH to use TCP-Wrappers/inetd super server

Tcp-Wrappers should be enabled to start and stop our OpenSSH server. Upon execution, inetd reads its configuration information from a configuration file which, by default, is /etc/inetd.conf. There must be an entry for each field of the configuration file, with entries for each field separated by a tab or a space.

  1. Edit the inetd.conf file vi /etc/inetd.conf and add the line:

              ssh	stream	tcp	nowait	root	/usr/sbin/tcpd	sshd -i


    The -i parameter is important since it's specifies that sshd is being run from inetd. Also, update your inetd.conf file by sending a SIGHUP signal killall-HUP inetd after adding the above line to the file.

    To update your inetd.conf file, use the following command:

              [root@deep] /#killall -HUP inetd

  2. Edit the hosts.allow file, vi /etc/hosts.allow and add the line:

              sshd: win.openna.com

    Which mean client IP with host name win.openna.com is allowed to ssh in to the server.

These daemon strings for tcp-wrappers are in use by sshd:


if you want to allow/deny X11-forwarding


for tcp-forwarding


port-name defined in /etc/services. Used in tcp-forwarding


If you do decide to switch to using ssh, make sure you install and use it on all your servers. Having ten secure servers and one insecure is a waste of time.

For more details, there are several man pages you can read:


OpenSSH secure shell client remote login program

ssh [slogin](1)

OpenSSH secure shell client remote login program


adds identities for the authentication agent


authentication agent


authentication key generation


secure shell daemon