Avaya SIP Software 3.2 for 1200 Series User Manual download pdf (Page 237)

Chapter 24: Security

This section specifies the behavior of the following security features:

• SIP over TLS

• Connection persistence

• SRTP

• SFTP

• SSH

SIP over TLS

To avoid security problems such as message integrity attacks, SIP over TLS uses Transport

Layer Security (TLS) to provide secure communication between the Avaya 1100 Series IP

Deskphone and the SIP proxy.

Transport Layer Security (TLS) protects SIP signaling traffic. It sits on top of the Transmission

Control Protocol (TCP), the preferred default protocol for SIP traffic. You can use TLS with a

user name and password to provide a means of server-only authentication. IP Deskphone-

specific Public Key certificates can provide even stronger mutual-authentication of both the

server and the IP Deskphone.

Using SIP over TLS protects SIP messages on a hop-by-hop basis. To achieve complete end-

to-end security through the use of TLS, each element involved in the system must also be

capable of securing SIP traffic using TLS.

Connection persistence

Connection persistence allows the IP Deskphone to establish a connection and monitor the

connection for failure by using "keep-alive requests.

The IP Deskphone establishes connection with the proxy using the commonly accepted ports.

Periodically, based on a configured timer value, the IP Deskphone issues a request to the

server to verify that the connection with the server at the TCP level is still active. When the IP

Deskphone discovers that the keep-alive packet has not been answered, it attempts to

reestablish a connection with the proxy. If this is successful, the IP Deskphone reregisters with

the proxy (and sends a new subscription requests where appropriate). If it is not possible to

reestablish the connection, the IP Deskphone falls back into a state where connection attempts

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Avaya SIP Software 3.2 for 1200 Series User Manual Page 237