Python support

Customize the cMAG-c behavior by applying user-defined Python scripts to inspect and modify control protocol packets.

Python scripts

Sending or receiving specific control protocol packets can trigger a user-defined Python script. Using the packet as input, the script applies a set of Nokia API calls to inspect and modify the packet. The script outputs the modified packet.

The direction of the triggering protocol message defines when the Python script runs:

  • ingress – before the subscriber management processing
  • egress – after the subscriber management processing

For example, when the cMAG-c receives a RADIUS Access-Accept message, a user-defined Python script can update the Alc-SLA-Prof-Str attribute in the message to a new SLA profile name. The system processes the modified packet and creates the session with the new SLA profile.

Python version and libraries

The cMAG-c Python support is based on Python version 3.11. The software includes the following libraries:
  • Python standard libraries
  • Nokia-provided TPSDA API
  • Cryptodome package, see PyCryptodome

For more information about the Nokia-provided TPSDA APIs, see cMAG-c TPSDA Python 3 API.

Supported protocol messages

The following tables list the supported protocol message types and direction.

Table 1. Supported direction for RADIUS messages
Message type Ingress Egress
Access-Request ✓
Access-Accept ✓
Access-Reject ✓
Account-Request ✓
Account-Response ✓
Access-Challenge ✓
Table 2. Supported direction for RADIUS CoA messages
Message type Ingress Egress
CoA Request ✓
DM Request ✓
CoA or DM Reply ✓

Operational commands

To check if a Python script is in service, use the following command.
info from state /subscriber-management python python-script <name> oper-state
To see the in-use source code of a Python script, use the following command.
info from state /subscriber-management python python-script <name> source-in-use
To bring a modified script in service, use the following command.
tools subscriber-management python python-script reload script

Configuring a Python script

You can customize the cMAG-c behavior with a Python script.

  1. Create a Python script file, and either save it in the /python folder of the Python pod or upload it to an HTTP or FTP server.
    Note: When storing the script file in the /python folder of the Python pod, it must be backed up on a cMAG-c-wide storage, so that the Python pod can still access the file if the pod is rescheduled to a different worker.
  2. Configure the URL of the script file. 
    subscriber-management python python-script
  3. Specify the trigger packet type, the direction, and the corresponding Python script in a Python policy. 
    subscriber-management python python-policy
  4. Reference the Python policy in the corresponding protocol configuration; for example, inside the radius-authentication-profile for the RADIUS authentication messages.

The following example configures to run the cf3:/test.py Python script file upon sending the RADIUS Access-Request message.

# info from running /subscriber-management python    
   python-script test {
        admin-state enable
        code {
            path /python/test.py
        }
    }
    python-policy rad {
        radius access-request direction egress {
            script test
        }
    }

# info from running /subscriber-management profiles radius-authentication-profile auth1
    server-selection-profile sel1
    python-policy rad
    password $aes1$AWPJEozXM6/vxG8=$P6tGQqEKHwszh6LDBJ3e1w==
    username-format {
        ipoe {
            format mac-address
            mac-format ab:ab:ab:ab:ab:ab
        }
    }