Red Hat Knowledgebase

This is likely due to a firewall blocking traffic. Samba runs over tcp ports 137-139 and depending on your environment 445 may need to be available as well. To see if this is the cause do the following:

1. On the Samba server stop iptables: service iptables stop
(Some systems may use service ipchains stop instead.)
2. Check /etc/hosts.allow and /etc/hosts.deny to make sure there are no rules prohibiting access.
3. On the client make sure there are no personal firewalls running.

Note: In order to turn your firewall back on, you can issue the following command:
service iptables start
(Some systems may use service ipchains start instead.)