Problem

Transfert CFT can be set to use source ports from the system Ephemeral range instead of the predefined range.

It is the best choice vs the range from the CFT configuration.

It ensures the provided port will be reserved and available.
It prevents from looping through the preset range until a port is found as free to be used.

It is really the recommended choice for a multi-node installation, otherwise, all nodes are sharing the same presets range.

It can be set independently for transfers, Sentinel notifications and for the synchronous CFTUTIL

For CFT settings, see the documentation for parameters below:

• For Transfers: CFTNET SRCPORT
• For the COMS: LOWPORT=0 (in the config command when using the synchronous CFTUTIL)
• For Sentinel: UCONF sentinel.trk_min_port & sentinel.trk_max_port

How to display the Ephemeral port range?

Resolution

You can display the available Ephemeral port range using the below commands:

Linux:

Command: sysctl net.ipv4.ip_local_port_range

Or

Command: cat /etc/sysctl.conf | grep net.ipv4.ip_local_port_range

The detail is also available from a cftsupport in the file sysctl-a.txt

Windows:

Command: netsh int ipv4 show dynamicport tcp

z/OS:

Command: tso netstat config

(check the range from EphemeralPorts in the output of this command)

IBM i

The default ephemeral port range on the IBM i is 5000 through 65535 for both TCP and UDP. This broad range may allow applications using ephemeral ports to bind to a port used by a server application causing the application to fail on startup because the server’s port is already in use.
IPCONFIG’s new ephemeral port options provide a solution to this problem. The ephemeral port range for both TCP and UDP can now be uniquely configured.

These options set the lowest and highest valid ephemeral port to be used by TCP or UDP. The value must be in the range of 5000 to 65535. The ephemeral port ranges can be modified at anytime; however, the newly configured values will not apply until after TCP has been restarted.

TCP Ephemeral Port Range Options
-tcp_ephemeral_low:
-tcp_ephemeral_high:

UDP Ephemeral Port Range Options
-udp_ephemeral_low:
-udp_ephemeral_high:

Displaying Ephemeral Port Ranges
-display