wphyer Posted December 3, 2022 Share Posted December 3, 2022 (edited) I'm having a weird problem when trying to SSH into a wireless SBC running Armbian (Ubuntu 22.04.01 LTS). When I try to SSH using the full domain name it doesn't respond: vmplayer@vm-play:~$ ssh -l potato potato-blue.mostly-harmless.wlan ^C If I force IPv4 then it'll connect vmplayer@vm-play:~$ ssh -4 -l potato potato-blue.mostly-harmless.wlan potato@potato-blue.mostly-harmless.wlan's password: Doing a lookup reveals both IPv4 and IPv6 addresses: vmplayer@vm-play:~$ nslookup potato-blue.mostly-harmless.wlan Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: Name: potato-blue.mostly-harmless.wlan Address: 10.20.30.246 Name: potato-blue.mostly-harmless.wlan Address: fdff:9cb4:dff::4bb Looking at the router, I can see that matches: Active DHCPv6 Leases Host IPv6-Address vm-play fdff:9cb4:dff::444 potato-blue fdff:9cb4:dff::4bb If I try to SSH using the absolute IPv6 address it doesn't respond: vmplayer@vm-play:~$ ssh -l potato fdff:9cb4:dff::4bb ^C Pinging also doesn't respond: vmplayer@vm-play:~$ ping fdff:9cb4:dff::4bb PING fdff:9cb4:dff::4bb(fdff:9cb4:dff::4bb) 56 data bytes ^C --- fdff:9cb4:dff::4bb ping statistics --- 7 packets transmitted, 0 received, 100% packet loss, time 6147ms Getting into the wireless device and getting the IP address, I'm getting several IPv6 addresses: potato@potato-blue:~$ ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000 link/ether ba:cd:d0:79:a7:3e brd ff:ff:ff:ff:ff:ff 3: wlx3c3300206d7c: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 link/ether 3c:33:00:20:6d:7c brd ff:ff:ff:ff:ff:ff inet 10.20.30.246/24 brd 10.20.30.255 scope global dynamic noprefixroute wlx3c3300206d7c valid_lft 43105sec preferred_lft 43105sec inet6 fdff:9cb4:dff::4bb/128 scope global noprefixroute valid_lft forever preferred_lft forever inet6 fdff:9cb4:dff:0:e94:aec2:3e03:6800/64 scope global temporary dynamic valid_lft 604707sec preferred_lft 86280sec inet6 fdff:9cb4:dff:0:4a0f:3507:b82:c02a/64 scope global mngtmpaddr noprefixroute valid_lft forever preferred_lft forever inet6 fe80::ff7c:79d3:28c8:2736/64 scope link noprefixroute valid_lft forever preferred_lft forever This is where it gets weird, if I try to SSH using fdff:9cb4:dff:0:e94:aec2:3e03:6800, it doesn't respond: vmplayer@vm-play:~$ ssh -l potato fdff:9cb4:dff:0:e94:aec2:3e03:6800 ^C If I ping it, it responds: vmplayer@vm-play:~$ ping fdff:9cb4:dff:0:e94:aec2:3e03:6800 PING fdff:9cb4:dff:0:e94:aec2:3e03:6800(fdff:9cb4:dff:0:e94:aec2:3e03:6800) 56 data bytes 64 bytes from fdff:9cb4:dff:0:e94:aec2:3e03:6800: icmp_seq=1 ttl=64 time=107 ms 64 bytes from fdff:9cb4:dff:0:e94:aec2:3e03:6800: icmp_seq=2 ttl=64 time=1.36 ms 64 bytes from fdff:9cb4:dff:0:e94:aec2:3e03:6800: icmp_seq=3 ttl=64 time=1.13 ms 64 bytes from fdff:9cb4:dff:0:e94:aec2:3e03:6800: icmp_seq=4 ttl=64 time=1.19 ms If I try to SSH using that address, that works now (but I don't want the IP address added): vmplayer@vm-play:~$ ssh -l potato fdff:9cb4:dff:0:e94:aec2:3e03:6800 The authenticity of host 'fdff:9cb4:dff:0:e94:aec2:3e03:6800 (fdff:9cb4:dff:0:e94:aec2:3e03:6800)' can't be established. ECDSA key fingerprint is SHA256:mJSIyTtITjN4muTp58tlfien/QOC7v41V0/qlcBS5MY. Are you sure you want to continue connecting (yes/no/[fingerprint])? no Host key verification failed. Now if I try to SSH using the full domain name, it works: vmplayer@vm-play:~$ ssh -l potato potato-blue.mostly-harmless.wlan potato@potato-blue.mostly-harmless.wlan's password: Last login: Thu Dec 1 00:11:21 2022 from fdff:9cb4:dff:0:fdea:5e03:da6f:3d2e I have no idea what's happening behind the scenes and I don't know why I can't connect at one point, then I can. Can anyone help or shed some light on this? Edited December 3, 2022 by wphyer Fix formatting 0 Quote Link to comment Share on other sites More sharing options...
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