When I attempt a SSH connection between client C and server S (both on the same LAN) the client looks up the server's key in the client user's
In the usual case for connection attempts, if the server's key is not found, the client is prompted to accept the server's key into the user's
known_hosts file . If the key is found then the connection process continues.
However I have a situation where if the connection request is forwarded through the LAN router/modem the lookup for the server's key fails even though the target server's key is there, and the client is not prompted. Instead the attempt is refused with
Connection reset by <IP of router>
Connect success to the LAN host directly using :
ssh -vvv stephen@acer
Connect failing to the LAN router to forward to acer using:
ssh -vvv stephen@michigan
This has just started happening. Any idea why?
Is the server key altered by the router?
Is the router replacing the target server's key with its own?
Is there some way of getting a look at the key that's being passed. I am calling with
ssh -vvvhave the SSH logging set to
VERBOSEbut see nothing I recognize as useful
Server host Ubuntu 18.04: Openssh-server/bionic-updates,bionic-security,now 1:7.6p1-4ubuntu0.1 amd64 Tested with clients: - Ubuntu 18.10: openssh-client/cosmic,now 1:7.7p1-4 amd64 - Ubuntu 18.04: openssh-client/bionic-updates,bionic-security,now 1:7.6p1-4ubuntu0.1 amd64 - Debian 9.5: openssh-client/stable,now 1:7.4p1-10+deb9u4 amd64 Modem: Arris Xb6