VMS TCPIP

[John Butt]

I understand that if you bind a socket to port zero VMS TCPIP will allocate a free ephemeral port which we can now listen on.

My question is what range of ephemeral ports does VMS use 1023-65535 full range or less?

Can TCPIP services be configure to restrict the range of free ports bind will use?

If so how is this done, TCPIP command ?
Please give an example for a range or say 32000 -32999

[Hoff · Accepted solution]

The core tool here is sysconfig, both to display and to modify the port range.

When last I looked, the default range is 49152 to 65535 port range. The ephemeral port range varies by platform and by implementation.

Details and commands are here:

http://64.223.189.234/node/530

Ephemeral ports and firewalls don't mix all that well.

[John Butt]

Thank you very much; the answer you gave hit the nail right on the head, and as you guessed the problems is with FTP and firewalls with a FTP failure rate between 5-10%.

[John Butt]

I how have all the information need to solve the problem.

Thanks again