SSH hangs after “Connection established”
hello hello.. im having a weird SSH issue and im running out of ideas
we have multiple servers using a tenable image across different VCNs and we added our SSH key during provisioning
initially SSH was asking for a password and i logged in through the tenable web interface, changed the default credentials, then checked the server and noticed the .ssh setup was missing so i created it, added our public key/user, fixed the permissions and after that SSH from our jump server worked fine for all servers except one (w new subnet)
for this one server SSH just hangs no password prompt no error
ssh -vvv stops here:
$ ssh -vvv <user>@10.x.x.x
OpenSSH_7.4p1, OpenSSL 1.0.2k-fips
debug1: Connecting to 10.x.x.x [10.x.x.x] port 22.
debug1: Connection established.
...
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.4
the interesting part is that SSH to the exact same server works from our PAM server!! but not from our jump server
the affected server is on a new subnet so im suspecting something network related, we checked the routing and it looks correct also checked the firewall but strangely we couldn’t see any traffic coming from the jump server
i ran sudo tcpdump -nn -i ens3 host <target_ip> and port 22 on the jump server while trying to SSH. the TCP connection gets established and the jump server sends a 21-byte packet (looks like the SSH client banner), but it keeps retransmitting it and gets no response back
i also tested MTU 1500 with ping -M do -s 1472 and got 0% packet loss
could this be asymmetric routing or some subnet/firewall/ACL issue specific to the path from the jump server?