Dynamic IP address and 'r' commands?

Dynamic IP address and 'r' commands?

Post by Barry Margoli » Wed, 08 Jul 1998 04:00:00





>Using RH5.1

>My local hostname is some daffy name I thought up. I PPP in to get my
>internet connection.

>I want to be able to use the 'r' commands (rlogin, rsh, rcp, etc) to
>another machine where I have an account.

>I tried giving
>cat > $HOME/.rhosts << EOF
>daffy vikas
>EOF

>on the remote machine, but that doesnt work because the remote machine
>doesnt know about 'daffy'. I cant add a entry for daffy in the remote
>/etc/hosts since daffy's IP address is dynamic.

Unfortunately, you're probably screwed.  Unless your ISP has some
arrangement to always assign the same name to the address they've assigned
to you (most don't -- they just have a unique name that's permanently
associated with each dialup address), there's nothing you can put in your
.rhosts file that will work well.

Before someone suggests something like dyndns.com, I've already thought of
that.  The problem is that those services only implement forward DNS.  The
r-command servers generally use reverse DNS -- they translate the client
address to a name and then check the .rhosts file to see if the name is in
there.  Reverse DNS is controlled by the ISP, not the dynamic DNS provider.

--

GTE Internetworking, Powered by BBN, Cambridge, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.

 
 
 

Dynamic IP address and 'r' commands?

Post by Michael Fu » Thu, 09 Jul 1998 04:00:00



> My local hostname is some daffy name I thought up. I PPP in to get my
> internet connection.

> I want to be able to use the 'r' commands (rlogin, rsh, rcp, etc) to
> another machine where I have an account.

> I tried giving
> cat > $HOME/.rhosts << EOF
> daffy vikas
> EOF

> on the remote machine, but that doesnt work because the remote machine
> doesnt know about 'daffy'. I cant add a entry for daffy in the remote
> /etc/hosts since daffy's IP address is dynamic.

> Options?

You could use ssh with RSA authentication: ssh provides 's' commands
that are equivalent to the standard 'r' commands and you get encryption
and (optionally) compression as well.  You'd configure your account on
the remote machine to let you in if you possess a certain key; it
doesn't matter what address you're coming from as long as you have the
key.  This requires ssh to be installed on both machines, so you might
have to convince the remote admin to install it (local laws permitting).

You can find more information about ssh at:

    http://www.cs.hut.fi/ssh/

Hope this helps.
--
Michael Fuhr
http://www.fuhr.net/~mfuhr/

 
 
 

Dynamic IP address and 'r' commands?

Post by Bria » Thu, 09 Jul 1998 04:00:00


Either go with 'ssh' instead. or put in ALL of your ISPs dynamic addresses
(IPs) in the .rhosts file (I don't recommend it though).

-Brian


> Using RH5.1

> My local hostname is some daffy name I thought up. I PPP in to get my
> internet connection.

> I want to be able to use the 'r' commands (rlogin, rsh, rcp, etc) to
> another machine where I have an account.

> I tried giving
> cat > $HOME/.rhosts << EOF
> daffy vikas
> EOF

> on the remote machine, but that doesnt work because the remote machine
> doesnt know about 'daffy'. I cant add a entry for daffy in the remote
> /etc/hosts since daffy's IP address is dynamic.

> Options?

> Thanks,
> Vikas

--
Brian Rectanus

 
 
 

Dynamic IP address and 'r' commands?

Post by Marijn Ro » Thu, 09 Jul 1998 04:00:00



> On Wed, 08 Jul 1998 02:14:36 -0700,

> >Either go with 'ssh' instead. or put in ALL of your ISPs dynamic addresses
> >(IPs) in the .rhosts file (I don't recommend it though).

> My RH5.1 doesnt seem to have ssh installed. Where can I get it? More
> information? How does 'ssh' solve this problem? How  do I configure it? I
> presume ssh is a secure implementaion of rsh.

ssh is a secure shell, yes. But it also relays X through the secure
channel. The way I locate it is by searching for ssh 1.2 (they're at
version 1.2.22 according to the homepage, but 1.2.25 is on their ftp
site) with for example metacrawler.

Bye
        Marijn

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