The first step in configuring your firewall for managed SIP services is to add the SIP server to the pre-defined service group. SIP is an Internet standard that is used to establish, maintain, and terminate multimedia sessions. SIP is available in most modern operating systems. You can find the server’s IP address on your customer portal. If you’re unsure about the correct port to use, refer to the SIP server’s website.
Adding this configuration to your Firebox will prevent unauthorized calls. For the best results, ensure that you enable SIP-ALG. This feature will enable you to limit the maximum number of media sessions and will log any requests that exceed that limit. Once configured, you can also identify outgoing SIP traffic from malicious sources by removing any IP addresses or private network information. Firebox will also allow you to block the use of a false user agent, which will prevent your company from receiving unsolicited calls.
UDP is used as the transport protocol for SIP. As a result, you should configure UDP Flood Protection on all of the managed devices in your network. You may find instructions on how to customise this in How to Configure UDP Flood Protection
Following the configuration of your firewall for managed SIP services, it is necessary to configure the SIP application-level gateway. For SIP calls, this type of gateway makes use of a NAT door, which is controlled by the firewall. This method allows SIP calls to be made by opening a NAT door or pinhole on the firewall. It also enables for the establishment of SIP connections through the NAT-door and IP address. When you need to block SIP traffic, a firewall pinhole is a suitable choice, but it is also possible to get past the firewall by using NAT doors.
It is necessary to configure access control lists for each of the different interfaces after you have finished configuring your firewall. Make certain that you have rules in place for both the source and destination IP addresses. In addition, make sure that you have a “deny all” rule in place for unapproved traffic. Acls can be applied to each interface in both the outbound and inbound directions. Once you’ve completed this task, you’ll be ready to leave. Keep a backup of your setup in case you need to restore it later.
You can configure your SIP Gateway by configuring the DHCP server on your computer. If you want to specify your Network Time Protocol server, use DHCP options 42 and 2. When you configure a SIP device, it will route the call to the provisioning server so that it can be provisioned there. On the supplied SIP phone, you will see a Teams logo as well as a soft-button for logging in. You are now ready to go after configuring the SIP gateway.
The configuration of the firewall is a significant step. Make sure to seek assistance from a security specialist to ensure that it is correctly configured. Firewalls must be maintained after they have been configured. Every six months, logs must be checked, firmware must be updated, vulnerability scans must be performed, and firewall rules must be evaluated to ensure that they are still effective. When using SIP, it is vital to realise that inspection and transformations can result in one-way audio calls. You must ensure that your firewall settings is up to date in order to avoid this from happening.
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