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Web: Example for Configuring Mail Filtering by Email Address or Attachment

This section provides an example for configuring mail filtering by mail address or attachment on the FW that serves as the security gateway on the intranet.

Networking Requirements

An enterprise has about 200 employees who work for two departments: sales and R&D. In addition, the enterprise has a domain name of its own and deploys a mail server on the intranet.

Figure 1 Mail filtering networking diagram

Restricts the mail transmission permissions to prevent confidential information from being leaked. To be more specific,

  • In the R&D department, only a few employees can send and receive mails, and the others can receive but cannot send mails.
  • In the sales department, all employees can send and receive mails, but the maximum size of attachments cannot exceed 10 MB.

Configuration Roadmap

  1. Construct the intranet for the enterprise and deploy the FW as the security gateway.

    • Add the mail server to the dmz.
    • Add all the employees in the sales department to the user-defined sale security zone.
    • Add all the employees in the R&D department to the user-defined research security zone.
    • Add the Internet to the untrust zone.

  2. Configure mail filtering.

    The mail filtering profile is zone-specific. Plan the mail filtering policies for the security zones.

    Purpose

    Configuration Roadmap

    Grants John and Jane the permission to send and receive mails, and other employees in the R&D department only the permission to receive mails.

    Enable mail address checks in the sending direction between the research zone and the dmz to filter out mails based on the sender addresses. Only John and Jane are permitted to send mails.

    Grants all employees in the sales department the permission to send and receive email, but restricts the attachment size per mail to a maximum of 10 MB.

    Enable the mail attachment control in the sending direction between the sale zone and the dmz to restrict the maximum attachment size to 10 MB.

Procedure

  1. Set the interface IP address and add the interface to a security zone.
    1. Add GE0/0/1 to the untrust zone.

      1. Choose Network > Interface.
      2. Click for GE0/0/1 and set the parameters as follows:

        Zone

        untrust

        IP Address

        1.1.1.1/24
      3. Click OK.

    2. Add GE0/0/2 to the dmz based on the preceding steps.

      The parameters of GE0/0/2 are as follows:

      Zone

      dmz

      IP Address

      10.2.0.1/24

    3. Create security zone sale and add GE0/0/3 to the sale zone.

      1. Choose Network > Zone.
      2. Click Add.
      3. Set the parameters as follows:

        Zone Name

        sale

        Priority

        60
      4. Select GE0/0/3 in Un-Added Interface. Click to add GE0/0/3 to the sale zone.
      5. Click OK.
      6. Choose Network > Interface.

      7. Click for GE0/0/3 and set the parameters as follows:

        Zone

        sale

        IP Address

        10.3.0.1/24
      8. Click OK.

    4. Create security zone research and add GE0/0/4 to the research zone.

      Set the parameters of the research zone as follows:

      Zone Name

      research

      Priority

      70

      Set the parameters of GE0/0/4 as follows:

      Zone

      research

      IP Address

      10.4.0.1/24

  2. Enable the mail attachment control in the sending direction between the sale zone and the dmz to restrict the maximum attachment size to 10 MB.
    1. Choose Object > Security Profiles > Email Filtering.
    2. Click Email Content Filtering.
    3. Click Add.
    4. Set the Name and Description of the mail filtering policy.

      Name

      profile_mail_sale_dmz

      Description

      Mail filtering policy for sale-dmz interzone

    5. Click Attachment Size and Quantity Control.

    6. Enter 10240 in Upper Limit of Sending Attachments.
    7. Set the action to Block in Action.
    8. Click OK.
    9. Configure the security policy for the sale-dmz interzone.

      1. Choose Policy > Security Policy > Security Policy.
      2. Click Add Security Policy and set the parameters of the security policy for the sale -> dmz interzone as follows:

        Name

        policy_sec_sale_dmz

        Source Zone

        sale

        Destination Zone

        dmz

        Action

        Permit

        Content Security

        Email Filter

        profile_mail_sale_dmz
      3. Click OK.

  3. Enable mail address checks in the sending direction between the research zone and the dmz to filter out mails based on sender addresses. Only John and Jane are permitted to send mails.
    1. Choose Object > Security Profiles > Email Filtering.
    2. Click Email Content Filtering.
    3. Click Add.
    4. Set the Name and Description of the mail filtering policy.

      Name

      profile_mail_research_dmz

      Description

      Mail filtering policy for research-dmz interzone

    5. Click corresponding to the sender address in Send Email.
    6. Set the action to Allow.

    7. In Selected, click Add.
    8. Set the mail address group as follows:

      Name

      mail_group_research

      Email Address
      • john_example@huawei.com
      • jane_example@huawei.com

    9. Click OK.
    10. Click OK.
    11. Click OK.
    12. Configure the security policy for the research -> dmz interzone.

      1. Choose Policy > Security Policy > Security Policy.
      2. Click Add Security Policy and set the parameters of the security policy for the research -> dmz interzone as follows:

        Name

        policy_sec_research_dmz

        Source Zone

        research

        Destination Zone

        dmz

        Action

        Permit

        Content Security

        Email Filter

        profile_mail_research_dmz
      3. Click OK.

  4. Click Submit.

Configuration Script

#                                                                               
sysname FW      
#                                                                               
interface GigabitEthernet0/0/1   
 undo shutdown
 ip address 1.1.1.1 255.255.255.0
#                                                                               
interface GigabitEthernet0/0/2   
 undo shutdown
 ip address 10.2.0.1 255.255.255.0
#                                                                               
interface GigabitEthernet0/0/3   
 undo shutdown
 ip address 10.3.0.1 255.255.255.0
#                                                                               
interface GigabitEthernet0/0/4   
 undo shutdown
 ip address 10.4.0.1 255.255.255.0
#                                                                               
firewall zone untrust                                                           
 add interface GigabitEthernet0/0/1
#                                                                               
firewall zone dmz                                                           
 add interface GigabitEthernet0/0/2
#                                                                               
firewall zone name sale id 4                                                    
 set priority 60                                                                
 add interface GigabitEthernet0/0/3
#                                                                               
firewall zone name research id 5                                                
 set priority 70
 add interface GigabitEthernet0/0/4
#                                                                               
mail-address-group name mail_group_research                                     
 pattern exact john_example@huawei.com                                          
 pattern exact jane_example@huawei.com                     
#                                                                               
profile type mail-filter name profile_mail_research_dmz                         
 description Mail filtering policy for research-dmz interzone
 send-mail sender filter-mode allow                                             
 send-mail sender group name mail_group_research                                
#                                                                               
profile type mail-filter name profile_mail_sale_dmz                             
 description Mail filtering policy for sale-dmz interzone
 send-mail attachment max-size 10240 action block  
#                                                                               
security-policy                                                                 
 rule name policy_sec_sale_dmz                                                  
  source-zone sale                                                              
  destination-zone dmz                                                          
  profile mail-filter profile_mail_sale_dmz                                     
  action permit                                                                 
 rule name policy_sec_research_dmz                                              
  source-zone research                                                          
  destination-zone dmz                                                          
  profile mail-filter profile_mail_research_dmz                                 
  action permit
Parent Topic: Configuration Examples for Mail Filtering
Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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