Ubuntu hosts.allow

Ubuntu hosts.allow file is the primary configuration file for TCP Wrapper. We can use hosts.allow file to filter access to our system and to secured a service. Setting up hosts.allow and hosts.deny files like protecting your system with a simple firewall. The complete manual for hosts.allow (and hosts.deny)file can be found in hosts_access manual. The manual contains all information you need to configure the hosts.allow file.

Here is a default Ubuntu hosts.allow file:

luzar@ubuntu:~$ cat /etc/hosts.allow
# /etc/hosts.allow: list of hosts that are allowed to access the system.
#                   See the manual pages hosts_access(5) and hosts_options(5).
#
# Example:    ALL: LOCAL @some_netgroup
#             ALL: .foobar.edu EXCEPT terminalserver.foobar.edu
#
# If you're going to protect the portmapper use the name "portmap" for the
# daemon name. Remember that you can only use the keyword "ALL" and IP
# addresses (NOT host or domain names) for the portmapper, as well as for
# rpc.mountd (the NFS mount daemon). See portmap(8) and rpc.mountd(8)
# for further information.
#

Example of Ubuntu hosts.allow configurations:

Mostly Closed

ALL: LOCAL @some_netgroup
ALL: .foobar.edu EXCEPT terminalserver.foobar.edu

Booby trap

in.tftpd: LOCAL, .my.domain

That's all.