TCPDCHK(8) System Manager’s Manual TCPDCHK(8)
tcpdchk – tcp wrapper configuration checker
tcpdchk [-a] [-d] [-i inet_conf] [-v]
tcpdchk examines your tcp wrapper configuration and reports all poten‐
tial 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 prob‐
-a Report access control rules that permit access without an
explicit ALLOW keyword.
-d Examine hosts.allow and hosts.deny files in the current direc‐
tory instead of the default ones.
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.
-v 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 dis‐
crepancies between what you want and what the program under‐
The default locations of the tcpd access control tables are:
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.
Wietse Venema (firstname.lastname@example.org),
Department of Mathematics and Computing Science,
Eindhoven University of Technology
Den Dolech 2, P.O. Box 513,
5600 MB Eindhoven, The Netherlands