[LUG] Testing an open socket

[John Horne <J.Horne@xxxxxxxxxxxxxx>]

Hi,

A quick question: does anyone know how I can test from within a c program
whether a given socket is still open or not, without sending anything down
it? Our big brother monitoring system opens a socket to a system using (say)
port 23 for telnet. The system has inetd configured for telnet but has tcp
wrappers around it and disallows any telnet access. In that respect the
socket gets closed by the remote system, but big brother doesn't see this.
Hence it reports that telnet is available on that system, when in fact it
isn't.

My thoughts are to try setting socket options and see if that gives any sort
of error to indicate that the socket has been closed. I haven't tested that
yet. Anyone done anything like this and know of a better way to test the 
socket?


Thanks,

John.

------------------------------------------------------------------------
John Horne, University of Plymouth, UK           Tel: +44 (0)1752 233914
E-mail: jhorne@xxxxxxxxxxxxxx
PGP key available from public key servers

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