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Chapter 7. UC Security > Firewalls and Application Layer gateways
Firewalls and Application Layer gateways
Firewalls are commonly used to protect networks, including those that transport voice traffic. Firewalls inspect the headers and, in some cases, payload of packets to ascertain which traffic they should permit and which traffic they should block. Stateful firewalls also maintain state information so that they know which traffic forms part of permitted flows and should be allowed.
In the case of voice traffic, several protocols and ports must be permitted to ensure that voice operates correctly across firewalls. These protocols include MGCP, H.323, SIP, SCCP, RTP, and RTCP. In the case of RTP and RTCP, the number of ports that could potentially be used number in the thousands.
Table 7-1 in the section, “TCP/UDP Port List,” lists the protocols and ports that firewalls should permit for CUCM to operate correctly.
