Sessions and Media

Maximum number of media streams per SIP session

Enter the number of media streams a single SIP session can handle. This restriction is primarily made for preventing DOS attacks.

Maximum number of concurrent sessions

Enter the number of concurrent SIP sessions which the firewall should handle. If the field is left empty, no upper limit is set.

Session timer

Enter the maximum time for a SIP initiated connection. When the timeout is reached, the firewall discards the media streams. The clients won't notice, as the connection is still active, but you won't hear anything as no media streams are let through. To avoid this, clients can regularly ask for new timeouts.

Limitation of sender of media streams

The firewall usually locks a media stream to the first sender IP address and port (for security reasons). Some SIP clients change ports during the first media stream packets, which will block the media stream from being let through the firewall. There are also scenarios where the media stream sender is changed to an entirely new sender.

You can select for the firewall to Lock to the first sender, which will render the behaviour described above. Allow multiple concurrent senders lets the media stream through even if ports and/or IP addresses change.

Ports

Enter the lower and upper limit of the port range that the firewall should use for media streams. The upper limit must be at least as high as the lower limit.