Opening Firewall Port to allow SQL replication Traffic to/from a SQL Cluster

I have a SQL Server 2005 cluster with two nodes (active/passive). Here's the configuration :

Cluster name : MYCLUSTER .
Cluster IP :
Node 1 (active node) hostname : NODE1
Node 1 IP :
Node 2 (passive node) hostname : NODE2
Node 2 IP :
Instance IP:

I need to have my Network Folks open the Firewall to allow SQL Replication Traffic to a SQL Server outside of our Network. We opened the Firewall using the IP of the SQL Instance ( but that did not do the trick. Can someone tell me what IPs have to be opened at the Firewall to allow the Replication Traffic?

Replication usually just uses the default ports of the instance. Opening up should be enough.

I'm assuming that the firewall is also open to the distributor and subscriber(s)?

Is SQL Server running on port 1433?