Re: [LUG] Testing an open socket

[Steve Marvell <steve@xxxxxxxx>]

On Wed, Jul 10, 2002 at 03:18:21PM +0100, John Horne wrote:
> 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.

If you select() on the socket and it's not available for write, then
it's dead dude.

There may be some SIGPIPE action too :)

Steve

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