Cisco PIX UDP 123

You should modify your existing Access List to add the traffic. It's good idea to copy existing ACL into the Notepad, modify it, and then replace old one. If you are doing a big change, it could be better to create a NEW access list (modified copy of the old one), leave old WORKING access-list unchanged, and then change your "access-group" command. If your new access-list fails, you can modify one command (access-group statement), and restore everything back.

Here is the example, how you could allow UDP/123:

access-list acl_in permit udp host any eq 123
access-group acl_in in interface inside

Also you can go to Cisco.com, and search for "pix configuration guide" - they have all bunch of examples.

Good luck,

Michael Shavrov
CCNP, CCDP, CCSP, Security+, Checkpoint CCSA, etc.
http://www.ciscoheadsetadapter.com