Open the shell and enter the "mount" command to list the mounts. "Connecting" to the server my cause the smb share to be mounted. If so, you can cd to the mount point and use "ls -l" to list the files and their permissions.
I thought you were between macs and using Ubuntu to transfer the files out of the NAT.
Since the mac also uses Samba, you can also use "smbclient" to access the share.
"smbclient -l <hostname>" to list the shares.
Try entering "help" and see which commands are available.
will access the share as you might with ftp.
If cifs is used (maybe not on the mac), you will have access to commands such as getfacl, setfacl. Try to list a problem file with "getfacl". It should list the permissions and ownership of the file. CIFS allows you to use and change unix/linux ownership & permissions on a samba share. Since the nas uses ext3, it uses linux and may support CIFS.
Here is an example of mounting a share (in Linux) on a nas device (maxtor external drive with ethernet port):
sudo mount -t cifs //maxtor/jschiwal /mnt/maxtor/ -o uid=jschiwal,gid=jschiwal,dir_mode=0777,file_mode=0666,rw
Look at the mount manpage on your mac or you could use Ubuntu as before.
Now I can use "ls -l" to list the owner and the permissions. I can even use "sudo chown bob" to change the owner, and chmod to change the permissions.
Another possibility is to create a user & samba owner to match the ownership of the files.
Also try to remember your previous username/password under the old system.