When configuring the FTP application layer gateway (ALG) profile, after enabling File Transfer Protocol Secure (FTPS), ALG switches to pass-through mode. This allows for an encrypted control connection to proceed. Once the connection is encrypted, it cannot be inspected for control commands, and firewall policies cannot be applied to the contents of the connection. For this reason, you must configure another virtual server, a wildcard CGNAT virtual server, to support the passive data transfer connections. FTPS only supports passive mode data transfers.

The wildcard and FTP virtual servers must share the same LSN pool, and address persistence must be configured on the pool. This configuration ensures that source address translation is consistent for the control and data connections that make up the file transfer.

1. On the Main tab, click Carrier Grade NAT > LSN Pools .
   The LSN Pool List screen opens.
2. Click Create.
3. In the Name field, type a unique name.
4. In the Configuration area, for the Persistence Mode setting, select Address or Address Port.
5. For the Member List setting, type an address and a prefix length in the Address/Prefix Length field, and click Add.
   If your pool uses deterministic mode, ensure that any address ranges you enter as a member do not overlap another member's prefix address ranges. For example, the address and prefix 10.10.10.0/24 overlaps 10.10.10.0/23.
6. Click Finished.

1. On the Main tab, click Carrier Grade NAT > ALG Profiles > FTP .
   The FTP screen opens and displays a list of available FTP ALG profiles.
2. Click Create.
3. Type a name for the profile.
4. From the Parent Profile list, select a parent profile.
5. Select the Custom check box.
6. Select the Translate Extended check box to ensure compatibility between IPv4 and IPv6 clients and servers when using the FTP protocol. The default is selected.
7. Select the Inherit Parent Profile check box to enable the FTP data channel to inherit the TCP profile used by the control channel. The check box is clear by default.
   Note: If disabled, the data channel uses FastL4 (BigProto) only.
8. In the Data Port field, type a number for an alternate port. The default value for the FTP data port is 20.
9. In the Settings area, select the Allow FTPS check box.
10. From the Logging Profile list, select the logging profile the BIG-IP system uses to configure logging options for various TFTP events.
    Note: If you configure a Logging Profile, you must also configure a Log Publisher.
11. Click Finished.

1. On the Main tab, click Carrier Grade NAT > Virtual Servers .
   The Virtual Server List screen opens.
2. Click the Create button.
   The New Virtual Server screen opens.
3. In the Name field, type a unique name for the virtual server.
4. From the Type list, retain the default setting Standard.
5. In the Destination Address field, type the IP address in CIDR format, such as 0.0.0.0/0 for IPv4 or ::/0 for IPv6.
   The supported format is address/prefix, where the prefix length is in bits. For example, an IPv4 address/prefix is 10.0.0.1 or 10.0.0.0/24, and an IPv6 address/prefix is ffe1::0020/64 or 2001:ed8:77b5:2:10:10:100:42/64. When you use an IPv4 address without specifying a prefix, the BIG-IP^® system automatically uses a /32 prefix.

   Note: The IP address you type must be available and not in the loopback network.
6. In the Service Port field, type 21 or select FTP from the list.
7. From the Protocol list, select TCP.
8. From the Protocol Profile (Client) list, select a predefined or user-defined TCP profile.
9. From the Protocol Profile (Server) list, select a predefined or user-defined TCP profile.
10. From the FTP Profile list, select an FTP ALG profile for the virtual server to use.
11. For the LSN Pool setting, select the pool that this server will draw on for addresses.
    Note: You must use the same LSN pool for the wildcard virtual server.
12. Click Finished.

1. On the Main tab, click Local Traffic > Virtual Servers .
   The Virtual Server List screen opens.
2. Click the Create button.
   The New Virtual Server screen opens.
3. In the Name field, type a unique name for the virtual server.
4. In the Destination Address field, type a wildcard network address in CIDR format, such as 0.0.0.0/0 for IPv4 or ::/0 for IPv6, to accept any traffic.
5. In the Service Port field, type 0.
   Note: Port 0 defines a wildcard virtual server that handles all types of services. If you specify a port number, you create a port-specific wildcard virtual server. In that case, the wildcard virtual server handles traffic only for the specified port.
6. Click Finished.

1. On the Main tab, click Carrier Grade NAT > Logging Profiles > ALG .
   The ALG logging profiles screen opens.
2. Click Create.
   The New ALG Logging Profile screen opens.
3. In the Name field, type a unique name for the logging profile.
4. From the Parent Profile list, select a profile from which the new profile inherits properties.
5. For the Log Settings area, select the Custom check box.
6. For the Log Settings area, select Enabled for the following settings, as necessary.

   Setting	Description
   Start Control Channel	Generates event log entries at the start of a control channel connection for an ALG client.
   End Control Channel	Generates event log entries at the end of a control channel connection for an ALG client.
   Start Data Channel	Generates event log entries at the start of a data channel connection for an ALG client.
   End Data Channel	Generates event log entries at the end of a data channel connection for an ALG client.
   Inbound Transaction	Generates event log entries of ALG messages triggered by an inbound connection to the BIG-IP® system.

7. Click Finished.