tcpdchk (8) - Linux Manuals

tcpdchk: tcp wrapper configuration checker


tcpdchk - tcp wrapper configuration checker


tcpdchk [-a] [-d] [-i inet_conf] [-v]


tcpdchk examines your tcp wrapper configuration and reports all potential and real problems it can find. The program examines the tcpd access control files (by default, these are /etc/hosts.allow and /etc/hosts.deny), and compares the entries in these files against entries in the inetd network configuration file.

tcpdchk reports problems such as non-existent pathnames; services that appear in tcpd access control rules, but are not controlled by tcpd; services that should not be wrapped; non-existent host names or non-internet address forms; occurrences of host aliases instead of official host names; hosts with a name/address conflict; inappropriate use of wildcard patterns; inappropriate use of NIS netgroups or references to non-existent NIS netgroups; references to non-existent options; invalid arguments to options; and so on.

Where possible, tcpdchk provides a helpful suggestion to fix the problem.


Report access control rules that permit access without an explicit ALLOW keyword.
Examine hosts.allow and hosts.deny files in the current directory instead of the default ones.
-i inet_conf
Specify this option when tcpdchk is unable to find your inetd.conf network configuration file, or when you suspect that the program uses the wrong one.
Display the contents of each access control rule. Daemon lists, client lists, shell commands and options are shown in a pretty-printed format; this makes it easier for you to spot any discrepancies between what you want and what the program understands.


The default locations of the tcpd access control tables are:



Wietse Venema (wietse [at],
Department of Mathematics and Computing Science,
Eindhoven University of Technology
Den Dolech 2, P.O. Box 513, 
5600 MB Eindhoven, The Netherlands


tcpdmatch(8), explain what tcpd would do in specific cases.
hosts_access(5), format of the tcpd access control tables.
hosts_options(5), format of the language extensions.
inetd.conf(5), format of the inetd control file.