HP-UX Reference (11i v3 07/02) - 5 Miscellaneous Topics (vol 9)

hosts_access(5) hosts_access(5)

Service trapping can be especially useful on network ﬁrewall systems. The typical network ﬁrewall only

provides a limited set of services to the outer world. All other services can be trapped just like the above

tftp example. The result is an excellent early-warning system.

DIAGNOSTICS

Problems are reported via

syslogd, the syslog daemon, at info, notice, warning and err lev-

els. An error is reported in the following cases:

• When a syntax error is found in a host access control rule,

• When the length of an access control rule exceeds the capacity of an internal buffer,

• When an access control rule is not terminated by a newline character,

• When the result of

%letter expansion would overﬂow an internal buffer,

• When a system call fails that should not.

WARNINGS

If a name server lookup times out, the host name will not be available to the access control software, even

though the host is registered.

Domain name server lookups are not case-sensitive. NIS (formerly YP) netgroup lookups are case-

sensitive.

AUTHOR

Wietse Venema (wietse@wzv.win.tue.nl)

Department of Mathematics and Computing Science

Eindhoven University of Technology

Den Dolech 2, P.O. Box 513,

5600 MB Eindhoven, The Netherlands

FILES

/etc/hosts.allow (daemon,client) pairs that are granted access.

/etc/hosts.deny (daemon,client) pairs that are denied access.