oss-security - Re: Re: Some fun with tcp

Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers

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Date: Wed, 15 Apr 2009 14:28:14 -0400 (EDT)
From: wietse@...cupine.org (Wietse Venema)
To: Tomas Hoger <thoger@...hat.com>
CC: wietse@...cupine.org, oss-security@...ts.openwall.com
Subject: Re: Re: Some fun with tcp_wrappers

Tomas Hoger:
> $ cat hosts.allow hosts.deny
> foobar: localhost
> foobar: ALL: DENY
> cat: hosts.deny: No such file or directory
> 
> $ ./test-hostsctl -d foobar unknown 127.0.0.1 unknown
> denied
> 
> (this is expected to be allowed)

My software behaves exactly as documented.

The hostsctl is called with a name of "unknown" and an address of
"127.0.0.1". There is no access rule that matches "unknown",
therefore, no such access rule will fire.

> $ cat hosts.allow hosts.deny
> foobar: localhost: DENY
> cat: hosts.deny: No such file or directory
> 
> $ ./test-hostsctl -d foobar unknown 127.0.0.1 unknown
> allowed
> 
> (this is expected to be denied)

Again, the software behaves exactly as documented.

The hostsctl is called with a name of "unknown" and an address of
"127.0.0.1". There is no access rule that matches "unknown",
therefore, no such access rule will fire.

> "test-hostsctl servicename unknown IP unknown" is what some
> applications do expecting tcp_wrappers to resolve IP to hostname.

I think that it would be a mistake to change a documented API that
has been in use for almost 20 years, just because some people can't
be bothered to read the API documentation.

	Wietse

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