# SSH using IPv6 addresses?



## michaelsanford (Jan 15, 2004)

I've read up a bit on IPv6, and even though I understand only the basic differences from IP (IPv4) some things still ellude me.

For example, an IPv6 address is this long 128 bit address. I see that localhost can be condensed to simply "::1", and when I *# ssh ::1* it works just fine, connects to localhost prompts to save RSA key etc etc.

However, I can't seem to SSH into my other computers with IPv6 addresses. For example, I sshed normally (with its rendezvous address) to my other Panther machine, and issued *ifconfig en0* to get the "inet6 fe80::203:93ff:fe86:f73a prefixlen 64 scopeid 0x4" address.

Sadly, *# ssh fe80::203:93ff:fe86:f73a* returns "ssh: connect to host fe80::203:93ff:fe86:f73a port 22: No route to host". Why is that, and what _exactly_ does that mean? Interestingly, when I *# ifconfig en0* on my localhost, and try to *# ssh (local IPv6 address-not ::1)* I get the same error message...


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## brianleahy (Jan 15, 2004)

IP6 is extremely bleeding-edge, support for it may be tentative at best.   I would suspect that for it to work properly all your computers, routers, etc. - including your ISP if you're using one - need to be running it.  

IF you're using a LAN with no internet connection, and all the machines are Macs set to IP6, you should be able to do it - unless you're using an IP4 router to connect them.  You could try running your CAT5 cable directly from one machine to the other.  Or use a 'dumb' hub instead.


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## michaelsanford (Jan 15, 2004)

All the macs are Panther, running in IPv6 auto-config mode (and all have addresses assigned them, which I can confirm in the Network preference pane). The router is (as far as I can see) IPv6-compatible, so I'm still dumfounded.

I was, at first, wondering if the address was mal-formed? The IPv6 address reported in the Network pane is different from the ifconfig en0 address:
Network Pane = fe80:0000:0000:0000:020a:27ff:feab:4f82
ifconfig en0 = fe80::20a:27ff:feab:4f82

I know the :: represents 0000, but then shouldn't it be more like fe80:::020a... ?


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