Re: nmap showing port 21 (ftp) open, but port is actually closed

[Paul Day <paulday () toll com au>]

On Fri, 9 Sep 2005, Mike Jones wrote:
> Has anyone ever seen this before, nmap is showing port 21 to be open on
> a machine on the internet, but 21 is not listening on that machine.  It
> happens to all machines I scan outside the local area network.

What nmap scan options were you using? By default, non-root users use the
system-supplied connect() mechanism for the TCP scanning, which I can't
see being able to false-positive. However, some of the other trickier
options could well do so.

PD

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