SSH does not try IPv4 after IPv6 fails (when DNS has addresses for both)
Created by: box293
Linux Mint 17.3 Rosa MATE Remmina version 1.2.0-rcgit.14 Desktop environment : MATE Connecting to (OS and version): any linux SSH session Connecting via (RDP, VNC, ...): SSH
I've noticed an unusual behaviour which I can reproduce.
If Remmina cannot connect to the DNS destination using IPv6, it doesn't try IPv4.
I've been setting up some servers to do some application testing. I already have entries in my DNS server for IPv4 and IPv6 for the new server.
core-030.box293.local has address 10.25.5.160 core-030.box293.local has IPv6 address 2001:44b8:3132:25:10:25:5:160
After deploying the servers from a template, they initially have their IPv4 address defined and active but not the IPv6 address. If I try and connect to the dns name core-030 it fails with the error:
Failed to startup SSH session: Timeout connecting to to core-030
If I jump to my Linux Mint terminal session and do a:
It takes a little longer than usual but then eventually connects. I'm assuming at this point it tries and connects to the IPv6 address, fails, and then trys the IPv4 address and succeeds.
My assumption is that Remmina tries to connect to the IPv6 address and fails. It doesn't then try the IPv4 address.
I'm not sure how all of this happens in the back end. I assume that the Linux Mint terminal resolves the core-030 object, receives an IPv6 and IPv4 record and tries the IPv6 record first (perhaps it tries the address based on the IP binding order).