Root Cause:
In the ssh library of guacd, the TCP socket for connecting to ssh server is created with AF_INET. So it does not support IPv6 address.
Solution:
When guacd creates the socket for ssh in guac_common_ssh_create_session(), stop using hard coded AF_INET for socket() call, use the address family which is returned from getaddrinfo().
Test:
- Connected successfully via ssh connections with IPv4 and IPv6 hosts.
- No connection error in guacd logs.
- Simulated a connection failure with specifying a ssh server which does not exist. guacd worked well in this case.