BBS and Router Questions

[+9640News]

OK, I have two TIPI's.  One a PEBox setup in a Geneve, and the other a sidecar for the TI-99/4A.

 

My router is setup to port forward port 9640 to my Windows system.  The BBS is setup for 20 inbound connections.

On Windows Explorer, I can connect to both \\TIPI and \\TIPI2 and copy files across without issue.

 

If I connect (telnet) to my BBS via the Geneve system to 9640news.ddns.net:9640, things work.

If I connect (telnet) to my BBS via the TI-99/4A system using Matt's Telnet connection, things work.

 

However, if I try connect both the TI and Geneve systems simultaneously, only one can connect, not both.  

 

Is there a router explanation?  I know I have seen multiple inbound remote calls in the past, so I am trying to understand what is going on at the router level.  I suspect I could add another inbound port if needed, but for moment, just trying to understand what is going on.

 

Beery

 

[wierd_w]

Yeah..

 

If both are using port 9640, then the one that has the port forwarding rule pointing to it will get all the outside traffic.

 

You need to change the active port on one of them, then put two port forward rules. One for the geneve driven one, and one for the 99/4A driven one.

 

 

Supplemental reading on NAT routing should clear all this up.

https://computer.howstuffworks.com/nat.htm

 

The short version:

 

You have a private network living inside your house, which the internet cannot see.

There is a public network outside your house (the internet), that your home network can connect to, via a broker. (your NAT router.)

 

From the internet side, there is a single device. The NAT router.  The NAT router is an intelligent device, and it keeps a table of which private IPs originate a connection to what public IPs, on what ports.  It makes use of its extended port area to handle additional requests. (Such as two or more private addresses using a port 80 request on a website). The NAT router will assign one port number to the first device, and another to the second, and that is how it handles both sessions.

 

However, since all connections made this way must originate inside the private network before transmissions can be sent back through, this makes running a server impossible.

 

Enter Port Forwarding.

 

Port forwarding makes a permanent port->PrivateIP:port assocation, and is a 1:1 relationship.  If you say port 9640 points at private IP 191.168.0.4's port 9640, that is ALWAYS where traffic delivered to the NAT router will be redirected to. 192.168.0.4's port 9540.  Always.

 

You want to either set up a fault tolerance configuration (which will be unique to your situation), so that one unit will handle traffic unless it gets too busy, then the other will.  OR-- you want to create another port forwarding rule at the router to redirect another NAT facing port the IP:port of the second device.

 

EG, a rule like

 

port 9641 ->192.168.0.5:9640

 

Then, from the internet, you would probe port 9640 for the first device, and probe 9641 and get the second device.

 

 

NOW-- servers that handle multiple incomming connections tend to use a PORT RANGE-- rather than a fixed port.  They have a single port used to negotiate a session, but still use a range of ports to direct the connecting device to get a unique session on.  See for example, passiv FTP.  Incomming connection happens on port 21, like expected. The server also has a range of additional ports it has earmarked for its use. It tells the incomming connection to reconnect on one of those other ports, and specifies which one. The connecting system does that, and then lives on the new connection. this frees port 21 for another incomming handshake.

 

To handle that, you need to set up port forwarding RANGES to the hosting IP in your router. Not all routers support ranges. (You will have to instead create a bunch of manual single forward rules for each port in the range if that is true. Nasty.)

Edited November 12, 2019 by wierd_w

[+arcadeshopper]

OK, I have two TIPI's.  One a PEBox setup in a Geneve, and the other a sidecar for the TI-99/4A.
 
My router is setup to port forward port 9640 to my Windows system.  The BBS is setup for 20 inbound connections.
On Windows Explorer, I can connect to both \\TIPI and \\TIPI2 and copy files across without issue.
 
If I connect (telnet) to my BBS via the Geneve system to 9640news.ddns.net:9640, things work.
If I connect (telnet) to my BBS via the TI-99/4A system using Matt's Telnet connection, things work.
 
However, if I try connect both the TI and Geneve systems simultaneously, only one can connect, not both.  
 
Is there a router explanation?  I know I have seen multiple inbound remote calls in the past, so I am trying to understand what is going on at the router level.  I suspect I could add another inbound port if needed, but for moment, just trying to understand what is going on.
 
Beery
 

Try using the local ip address and port of the BBS instead of the URL. Then you are not using the router

Sent from my LM-G820 using Tapatalk

[+9640News]

Thanks everyone.  Things make a bit more sense.

 

Beery