Modifying a Custom Media Type

You can edit an existing Custom Media Type to change its details.

The Custom Media Type allows you to define a hexadecimal signature that can be identified at the start or end of a media type file and the offset, in bytes, from the start or end of the file. See Custom Media Type Signatures for further information.

To modify a Custom Media Type:

1. From the Policy Center Home page, click Custom Media Types. The Manage Custom Media Types page appears listing the existing Custom Media Types.
2. Select the Custom Media Type you wish to modify and click Edit. The Custom Media Type page appears.

3. The Overview area enables you to provide a name and optional notes for the Custom Media Type. To edit these details:

• Move the mouse pointer over the Overview area and click Click here to change these settings.
• Edit the Name if required. Clearswift Gateway provides a default name. Change this to something more meaningful, if required.
• Edit the Notes if required. You can insert, change, or delete text in this field, which is empty by default.
• Click Save.

4. The Signatures area defines the list of signatures to search on. To add signatures to the list:

• Move the mouse pointer over the Signatures area and click New. The Add Signature dialog appears.
• In Signature Pattern, specify a signature to search for. You must enter pairs of hexadecimal characters separated by spaces. See Custom Media Type Signatures for further information.
• Specify whether the Signature Pattern is from the start of the file or end of the file using the drop-down list.
• Specify the Offset value in bytes.
• Click Add to add the signature to the list.
• The signature you defined is listed in the Signatures panel.
• Repeat the above steps for any additional signatures you wish to define.

5. To edit or remove a signature in the list, move the mouse pointer over the Signatures area and select the signature you wish to edit, then click Edit or Delete as required.
6. The Match All Signatures area enables you to match either all or any signatures. To edit these details:

• Move the mouse pointer over the Match All Signatures area and click Click here to change these settings.
• To match either all or any signatures, click the checkbox to Only match if all signatures are detected, as required.
• Click Save.

When you have finished modifying your content security policy you must apply the configuration for any changes to take effect. If the Gateways are configured as a group, any group changes should be applied to each Gateway.

You can create a Custom Media Type to reference from a Which Media Types clause in the What To Look For? section of a content rule.