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Re: port direction definition



Kamaraju S Kusumanchi wrote:
> In snapshot3.jpeg, the field (1) "Enter a name for the custom service:" can 
> be any random name. But what about (2)? Should I choose "Port Forwarding" 
> or "Port Triggering". 

Select Port Forwarding.  Port Triggering is used to dynamically make a
selection based upon outbound activity.  But in this case you want to
make a static configuration.

> The options in section 3 of snapshot3.jpeg are even more confusing. Under 
> the Protocol, there are three options - tcp, udp, both. I guess I should 
> choose "both"?

Select TCP.  Both is okay.  HTTP for your web server is a TCP protocol
and does not use UDP.  Therefore the exact match is TCP.  Specifying
BOTH will allow both TCP and UDP and since you are not using UDP it
won't hurt but will create a UDP route anyway.  But since nothing is
listening for UDP packets it won't hurt anything.

> For Global PortStart, Global PortEnd should I choose 8088?
> For Base HostPort, should I choose 8088?

Yes to both.  It is allowing you to specify a range of ports.  For
something like bittorrent you would need to specify a range of ports.
Since you only have one port you should give the same port number to
both ends of the range.

> What about Direction? In/Out?
> If the Direction is "In", then "Port Direction" can only be Dst.
> If the Direction is "Out", then "Port Direction" can be Dst or Src. Which 
> Port direction should I choose?

That is very confusing to me.  I vote to select In.  But I do not
understand why it would provide an option for Out.

After setting this up it is possible that the port forwarding will
only work from the external network inbound to your internal network.
That is, testing from your internal network may not be possible.  This
is because it would require your packages to exit your internal
network, then be translated through the NAT function of your router to
the external router address, then the router would need to realize
that it matches the external router address and route it back down the
same interface.  That feature is often not allowed.

Meaning that you will only be able to test if this is working from an
external network.  I often do this using an ssh connection to a text
terminal and then using lynx, w3m, or elinks to poke at the web site.

> Thanks for any help. This is utterly confusing to me. No amount of googling 
> helped me. There is no help page for this router. Did anyone get this 
> working or is my best choice to buy another router?

Those pages were confusing to me too.  :-)

Try the above suggestions first.  Try testing only from a remote
network.  The odds are good that you will have this working with this
modem.

If all else fails then I would fallback to setting up your Debian
machine as a DMZ host.  DMZ host was one of the other options from the
menu showed in your first screen image.  A DMZ host forwards all
incoming connections to the designated host.  This means that your
host machine will need to be secure against the hostile Internet.  It
will appear as if it is placed on the Internet directly.  But Debian
hosts are quite secure by default and are very suitable for that
purpose.  Review the open ports on your machine and if desired install
a firewall (I recommend Shorewall) to block inbound access from your
router to all but the web server.  This is quite easy and adds a layer
of protection.

Bob

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