This topic

Port Forwarding sftp blocked

jmcd-tf1 — Sun, 26 Jun 2022 11:23:55 GMT

I'm trying to setup port forwarding to allow sftp to a storage server. This has worked fine with a previous router, and is working fine on the LAN, but I cannot make it work from the external IP address.

Even if the firewall is disabled the port is blocked.

The storage RAID unit is assigned a fixed IP address and I can access this just fine on my internal network, using either sftp or ssh.

As a test, I've used Termius on Android phone with the wifi disabled so that it goes via the phone network to my external IP address. The log file for this shows:

starting new connection
starting address resolution
address resolution finished
connecting to port
connection established
starting SSH session
connection closed with error: connection reset by peer

this suggests the connection was made, but the storage box disconnected the session. But this doesn't make sense compared to using a LAN connection and it works. Is the smart hub doing something to disconnect the session?

The event log of the router doesn't contain anything relevant.

Anything else I can do to investigate further?

Re: Port Forwarding sftp blocked

licquorice — Sun, 26 Jun 2022 11:59:53 GMT

Make sure UPnP is disabled on the hub as it may be causing a conflict. Are you sure the application is actively listening on the relevant port, the port won't open unless it is.

Re: Port Forwarding sftp blocked

jmcd-tf1 — Sun, 26 Jun 2022 12:16:07 GMT

I'm sure the ssh/sftp application is OK as it works fine via the LAN ip. Only via external IP is it failing.
I tried disable UPnP but sadly didn't make a difference.

Re: Port Forwarding sftp blocked

licquorice — Sun, 26 Jun 2022 12:31:04 GMT

Yes, but on the LAN it doesn't have to open a port

Re: Port Forwarding sftp blocked

jmcd-tf1 — Sun, 26 Jun 2022 12:46:48 GMT

sorry, I'm not understanding you.
the unit is listening on port 22 on the LAN.
the router should be forwarding the external port to the device on port 22, but this is failing. even if I disable the firewall it still fails.

Re: Port Forwarding sftp blocked

licquorice — Sun, 26 Jun 2022 13:59:13 GMT

Yeah, ignore my last post.

How are you testing accessing the server, via an externally connected device or via your public IP but connected to the hub's wifi? If the latter, NAT loopback seems to sometimes work other times not, try via 4G.

Re: Port Forwarding sftp blocked

jmcd-tf1 — Mon, 27 Jun 2022 13:08:04 GMT

I'm using my phone with wifi disabled, i.e. not connected to the router but going via public network back to the router external IP address. I'm also setting up the phone as a hotspot so that my PC can test the router external IP. I'm using both a terminal app on the phone, and filezilla and also ssh on my PC to check the port.

To be clear, I'm aware that accessing the external IP from inside the LAN is a problem. Hencedisconnecting the devices from the LAN when testing the router external IP.

Reading other posts in the forum, it seems a common issue and I can't find it resolved.

Re: Port Forwarding sftp blocked

licquorice — Mon, 27 Jun 2022 14:38:27 GMT

I've just set up a test to a Raspberry Pi and can SSH to that just fine using external port 2022 and internal port 22 with my laptop tethered to my phone using 4G.

Make sure you are saving the rule, you need to click on the + symbol first before saving the rule.