Connecting to Ubuntu machine from PowerBook

Do you actually have Bonjour/Zeroconf running on Linux? If so, the appropriate command to connect would be:

ssh username@hostname.local

Sorry, I avoid Linux whenever possible. I'm curious. Why are you running Linux anyway? Why not just use your Mac?

You're launching X with that -X (or -Y), which means you'll need to issue that ssh command from an Xterm session. Install (if it's not already installed) X11 from your distro disks, launch it, then create an Xterm session, then issue the ssh command to the Linux box. (Terminal.app doesn't launch an X Window Server on your OS X system, which is what ssh -X (or -Y) needs to have running on your OS X box to allow the X displays to render on your OS X box. X11.app does that.)

You'll want to check with somebody that knows Ubuntu better than I do (or a Ubuntu-focused forum) around the set-up steps required for this, but starting up an RDP server over on Ubuntu would allow desktop sharing. This using either Screen Sharing within OS X, or installing and using the Apple ARD product, or the (free) CoRD package, can get you screen sharing.

In addition to RDP, remote X displays and remote desktops can also work here, but can tend to be a little clunky.

Or you can use the command-line to manage the Ubuntu box, of course.

The following assumes you're on a NAT'd network... I'd establish a DNS server going here (possibly on the Ubuntu box, if that's going to be up all the time), and also configure the Ubuntu box at a fixed address. Set your DHCP server to pass out the address of the Ubuntu box as the DNS server for your local network.

Here is how to use OS X as an X client (for an entirely different operating system, you'll need to adjust that part for Ubuntu) and a few links to how to set up the ssh private and public keys for a no-password or a passphrase-based login.

According to the stats for that project, you would be making a more significant contribution if you used your Macs. There are over 50% more Linux machines but their total processing contribution is virtual the same as Mac. Windows is even worse. Windows machines provide 2.45 times the processing power of the Macs, but it takes almost 10 times the number of machines to do that.

Setting up a login without a password is easy. Run:

ssh-keygen -t dsa

Make sure to provide a passphrase. Many instructions on the internet suggest using an empty passphrase. This is less secure but makes ssh much harder to use - except on a Mac, of course.

Then, copy the generated public key into the .ssh directory in the home directory of the account on Linux that you wish to login to. You should then be able to log in without a password.

But that is because you are using the Mac. My theory is that if you replaced the Linux machine with a Mac, you would get even more performance. I work with Linux machines every day and I don't think they are that fast at all. Sure the Linux server runs faster than my MacBook Pro, but it has 64 cores to my 2 cores and 128 GB RAM to my 4 GB. Is it 32 times faster? No way. Does the Linux machine lock up and need a reboot once a week - yep.

To be fair to my Linux system - it is about as souped up as they get. It has 64 cores and they get used. It saturates its 10 Gbit ethernet. Still, the amount of data I have to process with it requires overnight to run. Something flakes out in the fancy hardware drivers and causes it to lock it. That isn't typical Linux behaviour.

As for the iMac, there is nothing wrong with running it hard. That is what the fans are for. It is designed for style over cooling, obviously. An i7 machine is much faster than a Core 2 duo. That isn't a fair comparison. An equivalent Mac would also be a stellar performer, rock solid, look great, and run Microsoft Word.

Thanks for your long reply. I'm sorry to say that I don't really understand most of the technicalities in it. I have an extremely limited exposure to this so far, and have learned a few tricks to achieve what I want.

FWIW, you're playing in the proverbial deep end of the pool here. The shell can be quite unforgiving of certain sorts of mistakes, too.

Although in my first post I set out the command ssh -X user@user-etc, I can achieve the same effect that I want (or so it seems) by simply typing ssh user@user-etc.

For instance, the command sensors works with or without the -X.

Similarly, I can update and/or upgrade the software by issuing the appropriate commands (via aliases I created), with or without the -X.

With the -X (or -Y), ssh is intending to tunnel X Windows sessions, and (to function) the ssh -X (or -Y) command is issued from an X11.app Xterm environment. If you're not using remote X displays tunneled via ssh, then you don't need -X (or -Y) here, nor do you need X11.app for that matter.

Basically, I'm happy to acquire the few commands I need to carry out a limited number of tasks.

I'd spend a little time with the bash beginner's intro and related materials including the shell-scripting intro. If you're going to be using Terminal.app on OS X or managing a Linux box with the command line, you'll need some grounding in bash and related.

What I'm wondering, is whether I can shortcut the whole login process after the prompt, and do away with the need for a password.

That's what I was referring to in that reply, and in the linked ssh no-password article. (I don't have an article covering connecting to Linux, unfortunately. There are undoubtedly a few posted around the 'net, however.)

In general, you can get to a no-password login by setting up the certificate keys appropriately. ssh can use what is called a public-private key-pair, and the public key can be, well, public. The private key must be maintained like a password; privately. You first create a key-pair on OS X as described in the article, or from various other resoures around the 'net. With the private key kept on your local system (again, as described in the article) and with the public key transferred over onto the Linux system (and into its ssh directories), you will get an automatic login, or you'll be prompted for the passphrase associated with the key-pair. This passphrase is associated with the key-pair, and is not your login password.

There are other ways to do a no-password login including as setting up Open Directory and Kerberos on your local network, but those are more involved than setting up an ssh key-pair. Those are going to be more effort to set up.

ARD, screen sharing or CoRD are the other options, and entirely avoid the command-line, assuming the Linux box has RDP server capabilities configured.