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Configuration example: SIP session helper in transparent mode

6.0.0
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Configuration example: SIP session helper in transparent mode

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

The FortiGate 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 in transparent mode

General configuration steps

The following general configuration steps are required for this SIP configuration that uses the SIP session helper. This example 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 firewall service to ALL to allow traffic other than SIP on UDP port 5060.

This example assumes that you have entered the following command to enable using the SIP session helper:

config system settings

set default-voip-alg-mode kernel-helper-based

end

  1. Add firewall addresses for Phone A and Phone B.
  2. Add a security policy that accepts SIP sessions initiated by Phone A.
  3. Add a security policy that accepts SIP sessions initiated by Phone B.

Configuration steps - GUI

To add firewall addresses for the SIP phones
  1. Go to Policy & Objects > Addresses.
  2. Select Create New > Address to add the following addresses for Phone A and Phone B:
  3. 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 accept SIP sessions
  1. Go to Policy & Objects > IPv4 Policy.
  2. Select Create New to add a security policy.
  3. Add a security policy to allow Phone A to send SIP request messages to Phone B:
  4. Incoming Interface port1
    Outgoing Interface port2
    Source Phone_A
    Destination Address Phone_B
    Schedule always
    Service SIP
    Action ACCEPT
  5. Select OK.
  6. Add a security policy to allow Phone B to send SIP request messages to Phone A:
  7. Incoming Interface port2
    Outgoing Interface port1
    Source Address Phone_B
    Destination Address Phone_A
    Schedule always
    Service SIP
    Action ACCEPT
  8. Select OK.

Configuration steps - CLI

To add firewall addresses for Phone A and Phone B and security policies to accept SIP sessions
  1. Enter the following command to add firewall addresses for Phone A and Phone B.
  2. 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

  3. 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.
  4. 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

    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

    end

Configuration example: SIP session helper in transparent mode

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

The FortiGate 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 in transparent mode

General configuration steps

The following general configuration steps are required for this SIP configuration that uses the SIP session helper. This example 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 firewall service to ALL to allow traffic other than SIP on UDP port 5060.

This example assumes that you have entered the following command to enable using the SIP session helper:

config system settings

set default-voip-alg-mode kernel-helper-based

end

  1. Add firewall addresses for Phone A and Phone B.
  2. Add a security policy that accepts SIP sessions initiated by Phone A.
  3. Add a security policy that accepts SIP sessions initiated by Phone B.

Configuration steps - GUI

To add firewall addresses for the SIP phones
  1. Go to Policy & Objects > Addresses.
  2. Select Create New > Address to add the following addresses for Phone A and Phone B:
  3. 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 accept SIP sessions
  1. Go to Policy & Objects > IPv4 Policy.
  2. Select Create New to add a security policy.
  3. Add a security policy to allow Phone A to send SIP request messages to Phone B:
  4. Incoming Interface port1
    Outgoing Interface port2
    Source Phone_A
    Destination Address Phone_B
    Schedule always
    Service SIP
    Action ACCEPT
  5. Select OK.
  6. Add a security policy to allow Phone B to send SIP request messages to Phone A:
  7. Incoming Interface port2
    Outgoing Interface port1
    Source Address Phone_B
    Destination Address Phone_A
    Schedule always
    Service SIP
    Action ACCEPT
  8. Select OK.

Configuration steps - CLI

To add firewall addresses for Phone A and Phone B and security policies to accept SIP sessions
  1. Enter the following command to add firewall addresses for Phone A and Phone B.
  2. 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

  3. 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.
  4. 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

    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

    end