Giacomo Falchetti

thx for your answer @tomus,not quite the one I was looking for though.

Why IPv6 shouldn't do the job?

What I am interested to explore is

- to have a non-standard protocol port open for inbound traffic, say 12345

- have port forwarding or virtual server enabled on the router. I am not sure that the section IP filtering is actually the right one to make ssh connections working from outside

With the current (limited in my opinion) set of features available in my router, is remote ssh connection possible to happen?

I am trying to connect from an outside network via ssh with rsa keys to my Ubuntu server behind CH7465VF router.

I found the DS-Lite address of the router and I can ping6 its FQDN address without problem (IPv4 ping doesn't work).

Only few ports seem to be open from the outside, namely 21, 53, 80, 443, 8080.

In router management UI at 192.168.0.1 I disabled IPv6 Firewall and configured IPv6 port filtering as follows:

- Inbound

- Source IPv6 addresses = All

- Destination IPv6 address = my ubuntu server ipv6 address

- Protocol = TCP

- Source port = 8080

- Destination port = 22

- Allow

- Enabled

I chose 8080 as a test port to verify the ssh connectivity. I am trying several ssh options, the most relevant result to provide here is the following:

ssh -6 -p 8080  -vvv -i ~/.ssh/ubuntusrvrsa <user>@<routerDSLiteFQDN>

In the verbose log I can see that connection to router on port 8080 is established and not refused:

debug1: Connecting to <DSLiteFQDNaddress> port 8080.
debug1: Connection established.

then it throws 400 BadRequest

The request could not be understood by the server. Please verify the site you are attempting to access and retry.

I am trying different ssh options and getting different results, what I think is meaningful is that connections on port 8080 of the router are not refused.

Question is whether is possible to open different ports on the router from the outside and what configuration should be set up in the router configuration UI, which seems to be extremely basic and not many feature available.