FTP : How to find destination site address.

vasanthz · Posted: Wed Mar 21, 2012 11:36 am

Hi,

I have a query regarding FTP.
We FTP from LPAR A to LPAR B.

To initiate the connection we type in
TSO FTP XX.YY.ZZ.AA.BB

FTP happens successfully from LPAR A to LPAR B.
But when we go to LPAR B and issue a TSO NETSTAT or TSO HOMETEST, I was unable to find the XX.YY.ZZ.AA.BB on any of the NETSTAT or HOMETEST ouput.

One of my teammate said that the address is NAT'ed, but he too is an application programmer & does'nt know what it means. Could you please let me know how this thing works and is there anyway to find these addresses.

Wat sorcery is this.

Thanks in advance,

vasanthz · Posted: Wed Mar 21, 2012 1:11 pm

Hi,
after some searching found
"NAT (Network Address Translation) is the translation of an Internet Protocol address (IP address) used within one network to a different IP address known within another network. One network is designated the inside network and the other is the outside. Typically, a company maps its local inside network addresses to one or more global outside IP addresses and unmaps the global IP addresses on incoming packets back into local IP addresses. This helps ensure security since each outgoing or incoming request must go through a translation process that also offers the opportunity to qualify or authenticate the request or match it to a previous request. NAT also conserves on the number of global IP addresses that a company needs and it lets the company use a single IP address in its communication with the world."

Is there anyway we can see this translation addresses map?

PeterHolland · Posted: Wed Mar 21, 2012 1:24 pm

computer.howstuffworks.com/nat.htm

vasanthz · Posted: Wed Mar 21, 2012 1:49 pm

Thanks, Very informative article.

"a computer on an external network cannot connect to your computer unless your computer has initiated the contact. You can browse the Internet and connect to a site, and even download a file; but somebody else cannot latch onto your IP address and use it to connect to a port on your computer. "

Robert Sample · Posted: Wed Mar 21, 2012 2:32 pm

Your best bet is to contact your site support group. They will know how the different LPARs are configured, including any NAT being used. Without access to your site support group, finding the IP address may be impossible since the TCP/IP parameter file, which is where that data would reside, tends to be well protected by the site security package.