Avaya SIP Software 3.2 for 1200 Series Manual de usuario descargar pdf (Pagina 240)

How the IP Deskphone uses TLS

Transport Level Security (TLS) is a protocol for establishing a secure connection between two

end-points. After a connection is established using TCP, TLS negotiates the cryptographic

parameters used to secure the traffic that is sent over that connection. TLS, Public Key

Cryptography, and X.509 certificates provide either mutual or server authentication.

• Mutual authentication occurs when both the client and the server have public key

certificates assigned, that are used during the TLS handshake, to validate the identity of

both communicating parties. Both the server and the end point device certificates are

"signed" by well-known trusted certificate authorities.

• Server authentication occurs when a server has a certificate signed by a certificate

authority. The certificate is only used for the client to validate the identity of the server it

is connected to. After the TLS connection is established, the server can identify the IP

Deskphone through a user name and password.

How TLS impacts SIP

TLS impacts SIP in the following ways:

• URIs – contain transport parameters used to indicate the preferred method of contact.

For example,

Contact: Bob<sip:[email protected];transport=tls>

Important:

A transport parameter of TLS indicates that the server or client prefers TLS to be used

for communication.

SIP Software Release 3.2 adds transport=tls to the contact header when using TCP or

TLS.

• VIA header – contains the transport protocol used to send a request. For example, Via:

SIP3.2/TLSbob.company.com;....;alias

The IP Deskphone attempts to downgrade the allowed protocols if connection attempts

are made and fail. In order to avoid the IP Deskphone using an unsecure protocol, only

TLS is enabled.

The order of preference for protocols is always: TLS, TCP, and UDP.

You must enable the SIP TLS Listening port for incoming TLS connections to be made.

Security

240 SIP Software for Avaya 1200 Series IP Deskphones-Administration January 2012

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Avaya SIP Software 3.2 for 1200 Series Manual de usuario Pagina 240