Thanks for the comments. I do know that the setting in
system/schemes/default/timeout does effect the timing of the process. Not
sure in detail what the timeout is actually manipulating (RT folks - helps
us out here). But the purpose of the script at this point was just to get
an indea on where to start with /View since I will eventually expand this to
be more similiar to the "SHIELDS UP" service provided by Steve Gibson at
Gibson Research grc.com. I think a good book for Elan might be to document
a reference of all the items such as this timeout item and gives us the
purpose and use of these items.
Paul Tretter
----- Original Message -----
From: "Harold Grovesteen" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, April 10, 2001 6:15 AM
Subject: [REBOL] Re: timeout
> What you are attempting to do is open a TCP connection with a host on a
> specific port. The open request is initiated by the application
> (REBOL). Your TCP stack on your system actually handles the three way
> handshake to open the connection. Without an "open" timeout in the
> application, how long it takes for the open request to return to REBOL
> depends upon how the remote host responds (assuming the host is there)
> and timeout settings in the TCP stack. Some hosts will respond with an
> ICMP message indicating the port is not available and that should be
> very quick. Others may ignore the request in which case the TCP stack
> timeout controls how long it will take to complete. UDP is another
> story. Obviously, where actual communication occurs, network time
> contributes to how long the open request takes.
>
> There are also other ICMP messages the network may return which should
> terminate the open request. If REBOL passes these status messages back,
> assuming the TCP stack provides the reason for the failure to REBOL, you
> may want to look at the error to decide what to do. For example if the
> destination host is not available you don't need to go through a bunch
> of connection attempts, because none of them will succeed.
>
> And hopefully you are doing this program for a noble purpose. Internet
> security people consider this type of program an indication of an
> attempt to breach security--a hacker attack in progress.
>
> Harold Grovesteen
>
> Paul Tretter wrote:
>
> > here is an example script thats a port scanner (my intent is to make it
much
> > more than that). Right now it has system/schemes/default/timeout: 1
> >
> > However if you change it to 0:0.5 it responds much slower - why?
> >
> > REBOL [
> >
> > Title: "Port Scanner"
> > Author: "Paul Tretter"
> > ]
> >
> > system/schemes/default/timeout: 1
> >
> >
> > host: Ask "Enter ip address or fully qualified hostname
> > ex.(ftp.microsoft.com) "
> > port: to-integer Ask "Enter start port "
> > End: to-integer Ask "Enter End port "
> > newhost: rejoin [tcp:// host]
> >
> > while [(end + 1) <> port][
> > getports: rejoin [newhost ":" port]
> > either error? error: try [open getports][
> > disarm error
> > print ["nothing at port " port]
> > ][
> > print ["port " port " available"]
> > ]
> > port: port + 1
> >
> > ]
> >
> > halt
> >
> > ----- Original Message -----
> > From: "Holger Kruse" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Monday, April 09, 2001 7:10 PM
> > Subject: [REBOL] Re: timeout
> >
> >
> >
> >> On Mon, Apr 09, 2001 at 06:02:50PM -0500, Paul Tretter wrote:
> >>
> >>> Actually this seems quite buggy on win platform (win2k here). I get a
> >>
> > much
> >
> >>> longer timeout period with "0:0.5" than I get with "1".
> >>
> >> Cannot be :). Keep in mind that as I mentioned before the timeout only
> >> applies to individual reads, not to the other parts of communication,
> >> such as DNS lookup, connecting to a site, sending a request to a site
> >> etc.
> >>
> >> --
> >> Holger Kruse
> >> [EMAIL PROTECTED]
> >>
> >> --
> >> To unsubscribe from this list, please send an email to
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> >> subject, without the quotes.
> >>
>
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