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Hi everyone, According to previous discussion on fax client and server through FTP port 4559, no one can answer this firmly. What I think is that this is a problem due to NAT. This situation occurs similarly in Voice Over IP (VOIP). For example, in SIP, NAT will only change the source IP address for LAYER 3 only, but those embedded in IP message at or above Layer 4 (TCP/UDP layer or above) will not be translated to the NAT address. A voice channel (UDP) cannot be established as internal IP address is un-routeable. This can be solved by installing STUN server or Tunneling techniques. Will this be the same problem happened in Hylafax Client - Server Model? When Hylafax Client try to send a job request to Hylafax Server, after hand-shaking, a RTP/UDP port must be established on top of Layer 3 (IP Layer), however, the internal IP address embedded in IP packet used in Layer 4 (RTP/UDP layer) CANNOT BE MODIFIED by NAT. This internal IP cannot be route outside Internet. I think this problem could be solved by VPN or PPPoE, but I have not tried that before. Once the client can access the internal network behind the router, they can use fax client to send fax job to the Hylafax Server. Am I correct? -------------------- Thomas Tam ____________________ HylaFAX(tm) Users Mailing List _______________________ To subscribe/unsubscribe, click http://lists.hylafax.org/cgi-bin/lsg2.cgi On UNIX: mail -s unsubscribe hylafax-users-request@xxxxxxxxxxx < /dev/null *To learn about commercial HylaFAX(tm) support, mail sales@xxxxxxxxx*