I have a username on an ubuntu server, lets call it user a. I want to mount a directory from that server to my Mac, on which I have another username, lets call it user b. My problem is that, after I mount the directory (using the disk utility app) I can view files on the server but can't modify or create new files on it.

I checked, and if I change the permissions of the server directory so that its open to everyone (chmod 777), I can write to it. So what I need to know, is how can I specify the username and password in the NFS client when setting up the mount? That is, I want to specify that I'm trying to log in as user a to the server.