15.5. 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.
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Edit the inetd.conf file vi /etc/inetd.conf and add the line:
ssh stream tcp nowait root /usr/sbin/tcpd sshd -iTo update your inetd.conf file, use the following command:
: 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.[root@deep] /#killall -HUP inetd -
Edit the hosts.allow file, vi /etc/hosts.allow and add the line:
Which mean client IP 192.168.1.4 with host name win.openna.com is allowed to ssh in to the server.sshd: 192.168.1.4 win.openna.com
These daemon strings for tcp-wrappers are in use by sshd:
- sshdfwd-X11
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if you want to allow/deny X11-forwarding
- sshdfwd-<port-number>
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for tcp-forwarding
- sshdfwd-<port-name>
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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:
- ssh(1)
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OpenSSH secure shell client remote login program
- ssh [slogin](1)
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OpenSSH secure shell client remote login program
- ssh-add(1)
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adds identities for the authentication agent
- ssh-agent(1)
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authentication agent
- ssh-keygen(1)
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authentication key generation
- sshd(8)
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secure shell daemon