Why Would/How Could Ports Refuse to Open?

BTW .. what's the make/model of your router ?

Eagle51 said:

As long as your not trying to run both IIS Web Servers at the same time, then you can have both listen on port 80. You would have to adjust your port forwarding for port 80 to the correct internal IP. I would still set the binding for the internal IP of the given machine and not use the *.

Note: Been while since I've used IIS, but just stopping/starting and/or restarting IIS after making changes wasn't enough for it to pick up the changes, I had to restart the PC.

Yes, I'll believe that. A fairly common nuisance, eh? But the binding took according to 'localhost:81' which worked.

But the overall problem didn't go away. I've switched that other machine off now, anyway.

:)

p.s.

in another place where I'm looking for help with this i'm told we can have as many IIS instances listening on 80 as we like.... What Ports To Use For My IIS? : The Official Microsoft IIS Forums

Eagle51 said:

BTW .. what's the make/model of your router ?

It is local to Australia - a TG800vac. 'Telstra Gateway'. They're a rebadged something but I don't know what.

Ok, and in your router port forwarding, you changed the wan & lan port to 81 for the internal ip of the running web server ?

Edit: Have you double check windows firewall incoming rules ... to make sure port 80 and/or 81 is set/enabled ?

The router port forwarding rule looks like this:

Name. Wan Port Lan Port. Device. Address.
3300 3300 80 10.0.0.13 mac address.

And it doesn't work. netstat shows packets getting to 'syn_sent'

now if I change that to:

Name. Wan Port Lan Port. Device. Address.
3300 3300 80 10.0.0.88 mac address.

then it works. and netstat on that machine will show 'established'

hmmmm..... the wan and lan port should be the same port number. So if your wanting to use port 80, it would be
Name | Wan Port | Lan Port | Device | Address
HTTP | 80 | 80 | 10.0.0.XX

Note: XX is the internal ip of the running web server

Edit: Also double check your bindings so it's 10.0.0.XX port 80

no mate, I keep telling you - it works fine on the other machine.

it worked fine here previously but just in case i've lost my mind and my memory there's the other machine right there here and now today using exactly that configuration, those rules and they work.....

my understanding is:

a router gets a packet addressed to it with a port number, too.
it checks the port number against its 'port forwarded' list.
if it finds it then it looks to see what device and what port it should send the packet to.
that device is named in the port forwarding rule, named by its local IP - I showed an example of 10.0.0.13.
and the port to be used on that device is also named - port 80 in my example rule.

and right here is where you and I differ. You are saying it should be the same as the WAN port.
But why?
On the local machine you need an application 'listening' to that port.
The application we're talking about in this instance is IIS.
And IIS has a 'binding' which we've talked about or this thread has talked about and which is by default port 80.
That's where IIS 'listens'.

So the packet has to be sent to that port - port 80.

If I change IIS bindings to say 81, as I just did a while ago for demo and thorough checking purposes, then the rule must be amended to quote port 81 as the lan port and the URL 'localhost' must be amended to 'localhost:81'

Why doesn't it need 'localhost:80' normally? Because port 80 is the default for http traffic.

Now if it were something different, another app, perhaps a game, perhaps say Minecraft, then it would listen on a different port. I think Minecraft uses something like 25565.

So on the computer Minecraft is listening for Minecraft type packets (which probably only it can understand) on port 25565. And so we have to set the lan port at 25565.

And we find the WAN port is also 25565. Why? Because for convenience Minecraft packets all have the same port number attached: 25565. So they come into the router and it sees 25565.
It looks on its forwarding list and sees it.
And it sees a device address there too.
And it sees a port number on that device - 25565.

So yes. In that case they're the same. In that case and probably the majority of apps.

But not in this case.

As demonstrated by my second IIS installation on the second machine on the same lan receiving traffic without any problem at all.

Ok, ..... The way I see it, you've mapped wan/external port 3300 to lan/internal port 80. That's why, when you check it externally ... it shows port 80 as closed (port 3300 would show open I bet) and why localhost:80 works as it's internal and IIS picks it up cause that's the binding you set in IIS.

Edit: It's easy to check with your current 3300 to 80, have you tried your external IP with port 3300 to see if it connects ?

Yes. That's what I've been doing all along. Constantly.
You don't believe me.
I can't show you on this machine but this machine won't work - that's what the whole thread is about.
But the other machine. I'll go switch it back on.
I'll create a rule 3300 to 80 on that machine.
I'll give you my IP and you can enter IP + port and you'll see that index page.

There, it's done.
IP is 101.167.174.244 Port is 3300

go for it. :)

DUH ... I totally misunderstood, sorry about that. You want it mapped that way ... lol ... I was thinking you wanted to use port 80 in the standard setup, which is what I always use. So, the only thing I can think of is to make sure port 3300 is added to firewall incoming rules or maybe some other process on that machine is using port 3300, both of which I think you've already checked