Configuration example: SIP in Transparent Mode

Configuration example: SIP in Transparent Mode

The figure below hows an example SIP network consisting of a FortiGate unit operating in Transparent mode between two SIP phones. Since the FortiGate unit is operating in Transparent mode both phones are on the same network and the FortiGate unit and the SIP ALG does not perform NAT. Even though the SIP ALG is not performing NAT you can use this configuration to apply SIP security features to the SIP traffic.

The FortiGate unit requires two security policies that accept SIP packets. One to allow SIP Phone A to start a session with SIP Phone B and one to allow SIP Phone B to start a session with SIP Phone A.

 

SIP network with FortiGate unit in Transparent mode

o

Po                                                         Port2

 

SIP Phone A (PhoneA@10.31.101.20)

rt1                                                     P

FortiGate unit in Transparent mode SIP Phone B (PhoneB@10.31.101.30)

General configuration steps

The following general configuration steps are required for this SIP configuration. This example uses the default VoIP profile. The example also includes security policies that specifically allow SIP sessions using UDP port 5060 from Phone A to Phone B and from Phone B to Phone A. In most cases you would have more than two phones so would use more general security policies. Also, you can set the security service to ANY to allow traffic other than SIP on UDP port 5060.

1. Add firewall addresses for Phone A and Phone B.

2. Add a security policy that accepts SIP sessions initiated by Phone A and includes the default VoIP profile.

3. Add a security policy that accepts SIP sessions initiated by Phone B and includes the default VoIP profile.

 

Configuration steps – web-based manage

Before you begin this procedure you may have to go to System > Feature Select and turn on VoIP.

 

To add firewall addresses for the SIP phones

1. Go to Policy & Objects > Addresses.

2. Add the following addresses for Phone A and Phone B:

Category                                     Address

Name                                          Phone_A

Type                                            IP/Netmask

Subnet / IP Range                     10.31.101.20/255.255.255.255

Interface                                     port1

Category                                     Address

Name                                          Phone_B

Type                                            IP/Netmask

Subnet / IP Range                     10.31.101.30/255.255.255.255

Interface                                     port2

 

To add security policies to apply the SIP ALG to SIP sessions

1. Go to Policy & Objects > IPv4 Policy.

2. Add a security policy to allow Phone A to send SIP request messages to Phone B:

Incoming Interface                   port1

Outgoing Interface                   port2

Source                                        Phone_A

Destination Address                 Phone_B

Schedule                                    always

Service                                       SIP

Action                                         ACCEPT

3. Turn on VoIP and select the default VoIP profile.

4. Select OK.

5. Add a security policy to allow Phone B to send SIP request messages to Phone A:

Incoming Interface                   port2

Outgoing Interface                   port1

Source                                        Phone_B

Destination Address                 Phone_A

Schedule                                    always

Service                                       SIP

Action                                         ACCEPT

6. Turn on VoIP and select the default VoIP profile.

7. Select OK.

 

Configuration steps – CLI

To add firewall addresses for Phone A and Phone B and security policies to apply the SIP ALG to SIP

sessions

1. Enter the following command to add firewall addresses for Phone A and Phone B.

config firewall address edit Phone_A

set associated-interface port1 set type ipmask

set subnet 10.31.101.20 255.255.255.255 next

edit Phone_B

set associated-interface port2 set type ipmask

set subnet 10.31.101.30 255.255.255.255 end

2. Enter the following command to add security policies to allow Phone A to send SIP request messages to Phone B

and Phone B to send SIP request messages to Phone A.

config firewall policy edit 0

set srcintf port1 set dstintf port2 set srcaddr Phone_A set dstaddr Phone_B set action accept set schedule always set service SIP

set utm-status enable

set voip-profile default next

edit 0

set srcintf port2 set dstintf port1 set srcaddr Phone_B set dstaddr Phone_A set action accept set schedule always set service SIP

set utm-status enable

set voip-profile default

end


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