I think you can through the firewall as stated in this article:
- Click the System Preferences icon in the Dock.
- Click the Security icon.
- Click the Firewall tab.
- Click the Start button to turn on your firewall.
- Click the Advanced button.
- Click the Automatically Allow Signed Software to Receive Incoming Connections radio button to select it.
This enables the firewall. And, by default, virtually all incoming
TCP/IP traffic is blocked. You must enable each sharing method that
you want to be able to use. When you enable different sharing methods
from the Sharing pane in System Preferences (such as File Sharing or
FTP Access), you’ll notice that those types of traffic now appear in
the Firewall list. (In other words, when you turn on a sharing method,
the firewall automatically allows traffic for that sharing method,
which Snow Leopard calls a service.)
Click the up/down arrow icon to the right of any service to specify
whether the firewall should allow or block connections.
Sometimes, you might want to allow other traffic through your firewall
that isn’t on the firewall list of recognized services and
applications. At that point, you can click the Add button (which bears
a plus sign) to specify the application that your firewall should
allow. Snow Leopard presents you with the familiar Add dialog, and you
can choose the application that needs access.