how to ssh to a ipv6 ubuntu in a LAN?

I'm able to ping my Ubuntu box via command: (where c2h2ttt is listed in /etc/hosts)

c2h2@c2h2crawler:~/ttt$ ping6 -I eth1 c2h2ttt
PING c2h2ttt(c2h2ttt) from fe80::21b:21ff:fe22:e865 eth1: 56 data bytes
64 bytes from c2h2ttt: icmp_seq=1 ttl=64 time=10.3 ms
64 bytes from c2h2ttt: icmp_seq=2 ttl=64 time=2.06 ms
64 bytes from c2h2ttt: icmp_seq=3 ttl=64 time=1.33 ms

And when I try ssh -6 c2h2ttt it shows:

c2h2@c2h2crawler:~/ttt$ ssh -6 c2h2ttt
ssh: connect to host c2h2ttt port 22: Invalid argument

What's the correct command?

On the server side /etc/ssh/sshd_config has:

ListenAddress ::
ListenAddress 0.0.0.0

I was able to ssh to c2h2ttt via ipv4 on port 22. and netstat -lnt | grep :22 is

root@c2h2think:~# netstat -lnt | grep :22
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp6 0 0 :::22 :::* LISTEN

ufw is used and its allowing any inbound traffic on port 22

root@c2h2think:~# ufw status
Status: active
To Action From
-- ------ ----
22 ALLOW Anywhere

And the iptables configuration:

root@c2h2think:~# ip6tables -L -v -n
Chain INPUT (policy DROP 55 packets, 10758 bytes)
pkts bytes target prot opt in out source destination 0 0 ACCEPT all lo * ::/0 ::/0
Chain FORWARD (policy DROP 0 packets, 0 bytes) pkts bytes target prot opt in out source destination
Chain OUTPUT (policy DROP 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 0 0 ACCEPT all * lo ::/0 ::/0 

3 Answers

Try specifying the interface to the ssh client. The ping6 utility allows you to specify an interface, however ssh does not have a switch for that, you have to use this syntax:

ssh -6 fe80::21b:21ff:fe22:e865%eth1

Link local addresses aren't supposed to be used for SSH, they're for low-level protocol bootstrapping stuff. If you don't have an ISP-provided prefix to use on your network, then generate a unique-local prefix from fd00::/8 instead:

To connect SSH IPv6 you most have IPv6 ISP connectivity on your computer and than try as.

root@hostname[~]# ssh -6 2205:f200:40:401::9ab4:8b43

and this command it will ask first time to confirm SSH key. than type Y/Yes

Note: 2205:f200:40:401::9ab4:8b43 mean Your IPv6. This Only example of IPv6 so don't forget to replace you IPv6.