Support of IPv6

Home

4D v16.3

Support of IPv6

Starting with version 14, 4D supports IPv6 address notation. This concerns the following 4D integrated servers:

the Web server as well as the SOAP server,
the SQL server.

Note: For more information about IPv6, refer to the following specification: RFC 2460.

Support of IPv6 is transparent for users and for 4D developers: the program accepts either IPv6 or IPv4 connections indiscriminately when the listening "IP address" of the server is set to All (see Defining the IP Address for the HTTP Requests (HTTP server) and SQL Server Publishing Preferences (SQL server).

However, you should pay attention to the following points:

Indication of port numbers
Since IPv6 notation uses colons (:), adding port numbers may lead to some confusion, for example:
2001:0DB8::85a3:0:ac1f:8001 // IPv6 address 2001:0DB8::85a3:0:ac1f:8001:8081 // IPv6 address with port 8081

To avoid this confusion, we recommend using the [ ] notation whenever you combine an IPv6 address with a port number, for instance:
[2001:0DB8::85a3:0:ac1f:8001]:8081 //IPv6 address with port 8081

No longer any warning when TCP port is occupied
Unlike previous versions of 4D, when the server is set to respond on "all" IP addresses with 4D v14, if the TCP port is being used by another application, this is no longer indicated when the server is started. In fact, 4D server does not detect any error in this case because the port remains free on the IPv6 address. However, it is not possible to access it using the IPv4 address of the machine, nor by means of the local address: 127.0.0.1.
If your 4D server does not seem to be responding on the port defined, you can test the address [::1] on the server machine (equivalent to 127.0.0.1 for IPv6, add :portNum to test another port number). If 4D responds, it is likely that another application is using the port in IPv4.

IPv4-mapped IPv6 addresses
To standardize processing, 4D provides a standard hybrid representation of IPv4 addresses in IPv6. These addresses are written with a 96-bit prefix in IPv6 format, followed by 32 bits written in the dot-decimal notation of IPv4. For example, ::ffff:192.168.2.34 represents the IPv4 address 192.168.2.34.