[ale] Apache/CGI

cfowler cfowler at outpostsentinel.com
Tue Nov 28 21:48:16 EST 2006


On Tue, 2006-11-28 at 21:09 -0500, David Corbin wrote:
> In general, what you're trying to do sound very 'un-HTTP'.

You are right.  The only HTTP part is when we send
'GET /wherever/proxy.cgi'

The rest is old-fashioned bidirectional communications.

My theroy is that these KVM over IP vendors that I use saw that forcing
their applet to run over different ports other than 80 or 443 would
cause problems with firewall config.

Think about it.  You have a KVM -> IP device at a remote site behind
firewall.  You need to NAT port 80 on your firewall to that KVM device. 
To use the applet to communicate with with the KVM to take control of
the server you could use port 81.  You now have to nat 2 ports and one
is not standard.  It would just be easier to nat 1.  These devices do
that.  The web server runs on port 80 and the client runs on port 80
too.  How do they do that?  Magic?  

I think it is possible via 2 ways.

1.  pre-server
    Listen on port 80 and watch traffic.  See anything that
    starts out as XXXX send to the software that handles the 
    client piece.

2.  CGI.
    Client executes a 'GET /givemecontrol' and then
    the server fires off CGI that makes communication bidirectional.

With these small web servers designed for embedded devices I can do this
today with #2 above.  Apache does way too much processing on the stream
for me to do anything like this.

Would anyone on this list with a KVM over IP device raise their hands
and tell me what port the applet contacts the device to communicate on?

Chris





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