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Is it possible to setup port forwarding on a GS108tv2 switch? I have a unmanageable router at home which does not allow me to forward email sent to port 25 to a local IP (virtual machine) so this will need to be done at the switch level. Can it be done?
No, there is no other way: your router must let the traffic go by "opening" that port in its firewall. Without that, any incoming traffic is dropped, emails sent to TCP port 25, or any other traffic.
I'm not sure of your terminology: if this is a "modem", then only one PC can connect to it, directly. In that case, there is no firewall, all traffic goes through. You can connect an Ethernet Router to your modem, and this Router would come with configurable Firewall and solve your issue.
If this is already a "modem-router", then it is very surprising there is no configurable Firewall in it. After reading your post another time, maybe I was wrong, I'm sorry. I thought you had a "modem-router". It looks like you only have a cable modem, connecting one PC (your PC in that case gets your WAN IP address directly, there is no NAT). If this is right, you should procure a Router and just configure it for NAT and proper firewalling.
First, I think you need to make sure email traffic coming from the internet and sent to your WAN IP address (TCP port 25) is accepted by your unmanageable router. I might be wrong, but basic firewalling would simply drop any incoming TCP connection on your router. On a more standard router, with basic configuration capability, one must open that TCP port 25 in the firewall to let it go through. Are you sure email traffic sent to your WAN port 25 is going through? If that's the case, the following will apply. If not, I'm afraid you first need to fix that issue.
To answer your question, no, GS108Tv2 Smart Managed Switch isn't capable of "port forwarding".
I would advise M4100 series Fully Managed Switches for this need. You could go with M4100-D12G (GSM5212-100NES).
Then you could use an ACL (Access Control List) and attach it to the port connecting your router. Following explanations on M4100 Web User Manual page 358, one IP Extended rule would filter traffic with destination port = TCP 25 and redirect this matching traffic stream to the ingress physical interface (other port) where your PC / VM is connected.
I hope this helps, I'm sure the Community will assist you
Thank you for the very informative post! Well what I am trying to do is setup a mail server at home using smartermail. Since my cable modem is unmanageable I have no way to connect to the interface to look into traffic. Would you know of any other way to ensure traffic on port 25 is making its way to the modem and ensure it is not being dropped?
No, there is no other way: your router must let the traffic go by "opening" that port in its firewall. Without that, any incoming traffic is dropped, emails sent to TCP port 25, or any other traffic.
I'm not sure of your terminology: if this is a "modem", then only one PC can connect to it, directly. In that case, there is no firewall, all traffic goes through. You can connect an Ethernet Router to your modem, and this Router would come with configurable Firewall and solve your issue.
If this is already a "modem-router", then it is very surprising there is no configurable Firewall in it. After reading your post another time, maybe I was wrong, I'm sorry. I thought you had a "modem-router". It looks like you only have a cable modem, connecting one PC (your PC in that case gets your WAN IP address directly, there is no NAT). If this is right, you should procure a Router and just configure it for NAT and proper firewalling.
Ok you are a great resource and this is great information. I do have a wireless WIFI Dlink router where I can setup port forwarding and you are correct that I do have to configure a static IP on my laptop to connect to the cable modem for internet access. When using wifi I configure the same static IP on the wifi interface and then the wifi router allows DHCP connections via WIFI broadcast. Hope this clarifies my setup 🙂
