RE: Programmatically Pull the IP Address of The iSeries -- MIDRANGE-L

Terry,

RTVNETA    SYSNAME(&SYSNAME)


This is the SNA/APPC system name.

PING       RMTSYS(&SYSNAME)
RCVMSG     MSGTYPE(*INFO) MSG(&MSGDTA)
CHGVAR     VAR(&IPADDR) VALUE(%SST(&MSGDTA 57 12))

This is the TCP/IP DNS name. Nothing requires this to match the SNA name.Granted, many people would probably use the same name for both SNA andDNS, but there's no promise that this'll always work. Heck, you couldactually end up pinging a different system this way!

Also, there's nothing that forces the IP address to always be in position57 of the message. Anyone could use CHGMSGD to change the position. IBMcould re-word the text of the message in the next release of OS/400. Youcould install a different language on the system, and it'd be in adifferent position. You should be getting the address from the messagedata, rather than from the message itself!

Worse, you've hard-coded the length at 12. If the IP address were"207.100.123.206' your program would try to ping '207.100.123.' choppingoff the last number. If the IP address were '9.3.21.4' your program wouldgrab the whole address plus part of the wording that comes after it.

CHGVAR     VAR(&PATH) VALUE('net use T: \\' *TCAT +
            &IPADDR *TCAT '\CMTEMP')

This is Windows Networking. Only in newer versions of Windows can you usethe IP address in a UNC name, in older versions you have to use theNetBIOS name.

And, naturally, the NetBIOS name is not the same as the SNA name or DNSname. Granted, the admin might make them all the same for consistency,but he doesn't have to... just like the DNS name.

Furthermore, the whole idea of getting the IP address for a "machine" isflawed. IP addresses are assigned to network interfaces, they're notassigned to computers.

You'd be better off hard-coding the name, or putting it in a data areathat's easily changed, than you would writing code like the one you postedhere. That way, it's simple and won't mislead the next guy.

If you REALLY want to write program that figures it out yourself, you needto use the correct APIs. gethostname() will tell you the host name ofyour system. gethostbyname() will perform a DNS or host table lookup ona domain name to get it's IP address. The QZLSLSTI API can be used to getthe Windows Networking name of the server.