[X-Unix] rsync & ssh

[Stroller]

On Jul 5, 2004, at 10:30 pm, amoser at sewanee.edu wrote:

> ...in
> the wee hours of the morning the powerbook would connect to
> the imac via ssh, using public key authentication, and would
> then use rsync to synchronize some key folders. ...but I've recently 
> noticed that the ssh connection no
> longer works -- any attempt to ssh from the powerbook to the
> imac yields the following msg:
>
> WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
> @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
> IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
...
> It is also possible that the RSA host key has just been
> changed.

This means that the secure key associated with the ssh server on that 
IP address has changed.
Have you reinstalled the o/s on the iMac recently..?

> RSA host key for 10.0.1.2 has changed and you have requested
> strict checking.

Is it possible that the  iMac no longer has this IP address, and that 
it has been allocated to another machine on your LAN..?

> The fingerprint for the RSA key sent by the remote host is
> 5f:6a:9d:b6:63:b1:3b:5f:65:91:ee:62:44:e9:3d:d7.

This is the secure key that the server at 10.0.1.2 has sent.

> Please contact your system administrator.
> Add correct host key in /var/root/.ssh/known_hosts to get
> rid of this message.

It doesn't match the one in this file, which is the PowahBook's "master 
list" of trusted SSH keys.

> Offending key in /var/root/.ssh/known_hosts:1

Specifically on line one of that file.

> Keeping in mind that my knowledge of unix (and the technical
> terms associated with it) is woefully inadequate, any
> suggestions about what I need to do to get the ssh and
> backup scheme up and running again?

Check the iMac still has the IP address that the PowahBook is trying to 
connect to.
If it doesn't, then reassign IP addresses statically on your LAN so 
that it does.
If it does still have that IP address, delete the line corresponding to 
that IP address from /var/root/.ssh/known_hosts on the PowahBook.

> Also, it seems like there just aren't many unix resources
> (books, websites, etc.) geared toward showing people who
> aren't unix gurus but are competent with computers how they
> can leverage the unix commands inn Mac OS X to accomplish
> useful things like backups. (Man pages tend to be pretty
> unhelpful in this respect.) Any thoughts on this score?

Any "Unix resources geared to toward showing people who aren't unix 
gurus but are competent with computers how they
can leverage" ANY unix commands to accomplish stuff will be more or 
less applicable to Mac OS X.

Unfortunately, learning Unix is just plain hard. Any Unix "gurus" you 
meet will probably have suffered a great deal of frustration & 
exasperation in the acquisition of their knowledge, and they surely 
spent lots of time doing things the long &/or hard way in the process. 
Unix is *horribly* obscure & complex, and for no good reason other than 
compatibility with legacy systems. I personally spent several hours 
trying to change the time on my first Unix system, although that 
includes time spent reading some of the fascinating notes notes on 
world timezones which I am sure were distributed with that version of 
Irix (perhaps they were these 
<ftp://elsie.nci.nih.gov/pub/tzarchive.gz>). If you find what you're 
learning useful &/or interesting then stick with it! It will become 
easier.

Stroller.