TCP is two-way. If the master can't talk to the slave it won't work.
I'd suggest putting a new nic in the master and give it a private address
and use that network to talk between the master and slave.
Read this to learn how to setup a master/slave pair.
http://www.openldap.org/doc/admin22/replication.html
This may not necessarilly be accurate... The inability of the master to
"talk" to the slave is perhaps just a result of the non-routable address
that the slave will be using. If the slave can establish a TCP
connection to the master then you should have enough for replication to
occur via the syncrepl method. See the following links for more
information:
http://www.openldap.org/doc/admin22/syncrepl.html
FAQs:
http://www.openldap.org/faq/data/cache/1117.html
http://www.openldap.org/faq/data/cache/1125.html
Essentially the sync replication mechanism allows the client to connect
to the server and pass a cookie notifying the server of the state of
it's DIT. The server then sends changes back to the slave using standard
search result mechanisms. So if the slave can do a search on the master
it can replicate via syncrepl...
Lee Jensen