Keep in mind that IBM i can be both a client and a server.
When using it as a client many applications do not allow you to specify
which IP address to bind to. For example, if I am on my IBM i command
line and I type in
FTP "delivery01-bld.dhe.ibm.com"
it could go out on any of the interfaces listed at CFGTCP, option 1. And
if you have a few, like this sample from one of our lpars:
Internet Subnet Line Line
Address Mask Description Type
10.17.6.34 255.255.254.0 LANLIN *ELAN
10.17.6.35 255.255.254.0 LANLIN *ELAN
10.17.6.36 255.255.254.0 LANLIN *ELAN
10.17.6.37 255.255.254.0 LANLIN *ELAN
10.17.6.38 255.255.254.0 LANLIN *ELAN
10.17.6.39 255.255.254.0 LANLIN *ELAN
10.17.6.40 255.255.254.0 LANLIN *ELAN
10.17.6.41 255.255.254.0 LANLIN *ELAN
10.17.6.48 255.255.254.0 LANLIN *ELAN
127.0.0.1 255.0.0.0 *LOOPBACK *NONE
That can be problematic for some network conditions.
Some applications, such as http and smtp allow you to specify "bind
specific". But most of these are server specific, and even some server
specific ones do not allow you to specify bind specific.
Now, if I execute that IBM i ftp command,
and then from another session
do a netstat *cnn
I will see:
Connection identification:
Remote host name . . . . . . . . . . . . . . : dispby-101.boulder.ibm
Remote internet address . . . . . . . . . . : 170.225.15.101
Remote port . . . . . . . . . . . . . . . . : ftp-control
Local host name . . . . . . . . . . . . . . . : GDSSALES.DEKKO.COM
Local internet address . . . . . . . . . . : 10.17.6.37
Local port . . . . . . . . . . . . . . . . : 52481
Associated user profile . . . . . . . . . . . : ROB
Why did it go out my '37 address? Random selection?
We were having a real issue when trying to ftp new barcode setups from IBM
i to certain printers. Our network guy was trying to be very specific who
could ftp to a printer. This stuff caused us no end of grief.
We try to be nice to him. He hit it big in the dot com bubble and works
as a hobby. His other hobbies include collecting .50 caliber automatic
weapons. Carries a flip phone instead of a smart phone so the man can't
track him as much.
Rob Berendt
midrange.com
