To transfer a single file or just a couple of files, I usually use scp. But if you prefer an ftp-like interface, use sftp (comes as part of the ssh client on my Debian woody box). Normal ftp won't work unless you have an ftp server running on your Z, but sftp is better anyway.
I added a password to root on my Z, but you can still login without having to type it by sharing a key between the desktop machine and the Z:
(On the desktop)
Create a public/private key pair:
$ ssh-keygen -t rsa
Then copy the public key to your Z:
$ scp ~/.ssh/id_rsa.pub root@zaurus:/root/.ssh/authorized_keys
(Assumes "zaurus" is in your /etc/hosts)
Now you can ssh, scp or sftp from your desktop to the Z without having to type a password, even if a password is set.
But it seems to me that what the original poster wants is to be able to access the Internet from his Z via the desktop, i.e. you need to set up the desktop as a masquerading router. In brief:
- Enable networking between Z and Linux box (seems like you have got this far)
- Edit /etc/resolv.conf and add your DNS servers
- Type "route" on the Z and check your default route is through the Linux box
- On the Linux box, enable IP masquerading (NAT) in the kernel
- Use iptables (NAT) to enable masquerading
- Type "ping zaurususergroup.com" on the Z to confirm that everything works
- Now use AQPkg (or "ipkg update" and "ipkg install") to install packages.