Special Edition Using Linux®, Sixth Edition

tcpdchk

tcpdchk is a utility that enables you to see what kind of syntax errors you've made while creating your /etc/hosts.allow file. The utility has several options, including -d; this option enables you to start from a directory other than /etc, create your hosts.allow file, and then test against that file before replacing the one that you are currently using. The -d option reads the hosts.allow file in the current directory (rather than in /etc). Obviously, this option is somewhat limiting if you are already in /etc.

By using the -v option, you can see every line that tcpdchk is reading and how it operates. See Listing 34.1 for a sample output.

Code Listing 34.1. Sample tcpdchk Test Output

# tcpdchk -v Using network configuration file: ...