RT-AX86U Port Forwarding issue?

[RoadRunnerTR21]

I have been involved with database administration for 45 years. Mostly mainframe (DB2 and IMS) and Oracle on Linux server. I am not a network person by trade but I can get the basics done. I am also NOT a gammer. That said, my work environment consists of a Arris SB6183 modem connection to the internet. My RT-AX86U router connects to the Arris modem. I have 2 PC's hard wired to the router and several wireless devices as well. This configuration has always worked well for me with what I do. However, last week I ran into a situation that my network contacts cannot solve. I believe I have isolated the issue as being the router which is why I am here.

The issue:
Normally, I can run a stored procedure on a mainframe using a Windows client side product called IBM Data Studio. Once I start data studio, I issue a connection to a mainframe's IP address and then run my SQL statements, stored procedures, etc.. That process works great with or without the router. The problem occurs when I try to run the stored procedure in debug mode. In debug mode, data studio starts something called session manager on the Windows client machine. Before debugging starts, the mainframe tries to ping the session manager IP address to verify it is there and that's when things fail. This ping process times out because the mainframe can't ping the session manger IP address using the designated port which is 4553.

While trying to troubleshoot the problem, I tried connecting my client machine directly to the modem. When I ran debug mode, the process worked correctly.

Modem IP is 43.223.xxx.xx
Client machine IP is 192.168.56.1
The mainframe was pinging 192.168.56.1:4553

This process fails when the router is in the mix.

Modem IP is 43.223.xxx.xx
Router IP is 192.168.50.188
Client machine IP is 192.168.56.1
The mainframe was pinging 192.168.56.1:4553 and it failed to connect

When I contacted my network guy for some help, he suggested port forwarding. So I went to Virtual Server/Port Forwarding under WAN and added 192.168.56.1 for internal IP address, TCP for protocol and 4553 for external port and applied the changes. That did not work. My network guy also suggested turning on UPnP and ICMP but that did not fix the issue.

What can I do to try and remedy this situation?

Thanks

 

[ColinTaylor]

Are you sure your local IP addresses are those that you said? If your SB6183 is a modem (not a router) then whatever you plug directly into it should get a public IP address (e.g. 43.223.xxx.xx), not a private IP address (192.168.56.1).

Or is your PC connecting to the mainframe using a VPN client? It seems strange (and worrying) that you appear to have a database that's exposed to the public internet.

 

[RoadRunnerTR21]

No VPN involved for this application. This particular mainframe is a testing sand box. Not production.

I got the IP addresses from each the two different configurations by running IPCONFIG. I got the modem address using something called IPChicken.com.

So if I understand you correctly, by plugging the router into the modem, the IP address of the router should be 43.223.xxx.xx?

Also when I run IPCONFIG, it says:

Ethernet adapter Ethernet 2
IPv4 address 192.168.50.188
Default gateway 192.168.50.1

Ethernet adapter Ethernet:
IPv4 address 192.168.56.1
Default gateway is blank

 

[ColinTaylor]

So if I understand you correctly, by plugging the router into the modem, the IP address of the router should be 43.223.xxx.xx?

Yes, the router's WAN address address should be something like that. The router's LAN subnet (and therefore all PCs connected to it) should be 192.168.50.x

So I can't see how your "Client machine IP is 192.168.56.1". That makes no sense. Even if that was your PC's IP address the mainframe wouldn't be able to ping it because it is a private IP address and as such is not routable over the internet (unless using a VPN).

Also when I run IPCONFIG, it says:

Ethernet adapter Ethernet 2
IPv4 address 192.168.50.188
Default gateway 192.168.50.1

Ethernet adapter Ethernet:
IPv4 address 192.168.56.1
Default gateway is blank

I don't know what 192.168.56.1 is. Presumably it's a second Ethernet adapter that isn't being used. Or maybe a virtual interface created by Data Studio. Try running ipconfig /all for more detailed information.

How do you know the mainframe was pinging address 192.168.56.1:4553 and not the 43.223.xxx.xx address?

Also, when you say "ping" do you mean ICMP ping, because ICMP doesn't use port numbers (like 4553). Or do you mean a TCP ping?
EDIT: OK, it looks like port 4553 is a Debugger Session Manager port. So it's not ICMP.

 

[ColinTaylor]

I found some more information about Session Manager.

I'm guessing you're running db2dbgm.bat and looking at the port and IP address it displays. Correct? If so it looks like it's picking up the wrong IP address.

Can you edit db2dbgm.bat to specify the correct IP address, 192.168.50.188? You would then need to forward TCP port 4553 on the router to 192.168.50.188.

 

[RoadRunnerTR21]

I looked at my network connections and found that Ethernet was enabled for VirtualBox Host-Only Ethernet Adapter. When I disabled that, I now have one IPv4 Address of 192.168.50.188. The default gateway is 192.168.50.1.

I tried to run Data Studio again using port 4553 but it failed. However, unlike before when it showed the mainframe IP Address was pinging 192.168.56.1:4553, this time it just failed and did not display the IP address it was pinging.

 

[ColinTaylor]

See my previous post and check that your port forwarding rule on the router is directed to 192.168.50.188 and not 192.168.56.1 which is what you had before.

If you haven't already done so you might need a rule setup in the Windows firewall the allow unsolicited incoming traffic on port 4553. You can test whether this is the case be temporarily turning off the Windows Firewall and seeing if it then works.

 

[RoadRunnerTR21]

I'll give it a try

 

[RoadRunnerTR21]

The test failed. I did see a message that 192.168.50.188:4553 was being pinged by the mainframes IP address. So it is picking the correct IP address. I disabled both Norton 360 firewall and the IPv4 firewall on the router. That did not remedy the situation.

 

[RoadRunnerTR21]

The message I see generated by data studio is a popup that says
"Initializing debug session
Pinging session manager (192.168.50.188:4553) from 62.33.xx.xxxx"

The last IP address is a fake mainframe IP address but I know it is the correct IP address

 

[ColinTaylor]

Pinging session manager (192.168.50.188:4553) from 62.33.xx.xxxx"

You need some way of telling it to use your public IP address (43.223.xxx.xx) not the private IP address (192.168.50.188).

 

[RoadRunnerTR21]

I can specify a specific IP address. My question is what port do I use?

 

[RoadRunnerTR21]

That worked! I told it to use my public IP address with port 4553 and it worked perfect! I can't thank you enough for your help Colin!

 

[ColinTaylor]

That's good news.

 

[RoadRunnerTR21]

You have a great weekend where ever you are!