McKown, John wrote:
-----Original Message-----
From: IBM Mainframe Discussion List
[mailto:[EMAIL PROTECTED] On Behalf Of Hunkeler Peter (KIUK 3)
Sent: Friday, October 20, 2006 7:27 AM
To: [email protected]
Subject: Re: Multiple FTP Problems
I may be on the wrong track again, but anyway I can't get rid
of the thought about "not enough TCP ports" available.
- You define the ephemeral port range in TCPIP's profile
- Each transfer of a file needs a new port.
- A TCP connection stays in Close-Wait state for some time
(2 minutes?) after the close, so the port is still blocked
Too many file transfers in a short time and too small an
ephemeral port range might lead to no port available.
Glad if someone corrects me if I'm mixing up things again.
Peter Hunkeler
CREDIT SUISSE
I think this will depend on whether you are using "active" or "passive"
ftp. With "active" ftp, all data connections are originated from the
__server__ to the client, using port 20 on the server. There are no
ephemeral ports used. Ephemeral ports are only used for "passive" ftp
transfers. That's where an ephermeral port is allocated by the ftp
server, which listens on that port, and connected to by the client. Or
do I have that backwards again??
--
John McKown
Senior Systems Programmer
HealthMarkets
Keeping the Promise of Affordable Coverage
Administrative Services Group
Information Technology
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Nope, you have it correct. When using active ftp the server is really
the client and the client is really the sever for the actual data
transfer connection. The sever always uses port 20 as the source port
and the client side uses ephemeral ports.
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