Yes you can! If you are having problems with getting dnetc to connect through a firewall, you should speak to your local sysadmin/computer expert in the first instance.
Alternatively, you can always get (fetch) and send (flush) work units via email.

If you wish to download 123 packets of work for the OGR-28 project, you should enter "numblocks=123" and "contest=OGR" on separate lines in the body of an email to fetch@distributed.net. If you don't enter the "contest=OGR" line, it will download packets of work for the RC5-72 project instead.

To send us completed work, attach your buff-out.r72/buff-out.og2 file to an email and send it to flush@distributed.net. Please note that the flush@distributed.net service can only handle messages encoded in uuencode or base64.