Cloudflare Developers•11mo ago

CF Tunnel SSH Not Connecting

I'm having some trouble getting a CF Tunnel SSH session established. I have an active and healthy (confirmed with other apps on the same tunnel) CF Tunnel working on another server, running in a docker container. I want to enable CF Access SSH through the browser-based rendering. I went ahead and set up the Public Hostname on the Tunnel's page and set it to ssh://<server2> as the address. I'm getting a white screen when loading into the public hostname being set. On the host, SSH logs show:

Jan 10 23:58:05 athens sshd[3660]: Connection from <server1> port 43228 on <server2> port 22 rdomain ""
Jan 10 23:58:05 athens sshd[3660]: error: kex_exchange_identification: Connection closed by remote host
Jan 10 23:58:05 athens sshd[3660]: Connection closed by <server1> port 43228

Jan 10 23:58:05 athens sshd[3660]: Connection from <server1> port 43228 on <server2> port 22 rdomain ""
Jan 10 23:58:05 athens sshd[3660]: error: kex_exchange_identification: Connection closed by remote host
Jan 10 23:58:05 athens sshd[3660]: Connection closed by <server1> port 43228

I confirmed that no firewalls are active and that server1 is able to properly SSH into server2 normally. Further, I also tried with a different CF Tunnel installed on the server2 directly with the same kex_exchange_identification error. This isn't the first time I've set up SSH over CF Tunnels, but this is the first time I'm seeing this and I'm incredibly baffled. Any help would be appreciated!

1 Reply

musicman123 — FJLaboratoriesOP•11mo ago

to add, the CF Tunnel logs show the following message:

upstream->downstream copy: read tcp <server1>:49046-><server2>:22: use of closed network connection

upstream->downstream copy: read tcp <server1>:49046-><server2>:22: use of closed network connection

I'm dumb - I didn't specify browser rendering on teh Application settings tab...

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CF Tunnel SSH Not Connecting