This is a cross-post. I've posted it in a couple of other places, mostly because I am completely baffled and have no idea where to turn. Here's the issue: I've got an AS/400 sitting behind a router. The router performs NAT for me, but also does some port forwarding if I ask it nicely. For example, requests to my realworld IP address on port 25 go to my Linux machine, which has an internal address. I have a Linux box, a W2K workstation and an AS/400, all sitting behind a router. Let's say my addresses look like this: Realworld IP: 220.127.116.11 Router: 10.10.10.101 Linux: 10.10.10.102 AS/400: 10.10.10.103 W2K WS: 10.10.10.104 Now, if I forward port 80 to the Linux box it works just fine. I do an HTTP GET to my realworld IP, and up comes the welcome page from my Linux machine. This is way cool. However, I can't seem to get it to map to the AS/400. I can access the AS/400's HTTP server INTERNALLY just fine, by using my 10. addressing. But it won't listen to the mapped request. So I did a little sniffing, and found out something interesting. When my W2K machine makes a request using the realworld IP, the following occurs on my network: 10.10.10.104 --> 18.104.22.168 (initial request) 22.214.171.124 --> 10.10.10.102 (request forwarded to Linux box!) 10.10.10.102 --> 126.96.36.199 (response from Linux box to router) 188.8.131.52 --> 10.10.10.104 (response finally returned to me) Notice how the router handles the port forwarding... it sends a request to the destination device, but only after spoofing the source address to be the realworld address of the router! I don't have the time to sit and think it through; I'd think you would just leave the real source address in place, or else pass the WAN address of the router (not the realworld address). I tried picturing the possible combinations of multiple requests forwarded to multiple devices through multiple IP addresses, and I started to get ill. And regardless of the WHY, this is how it works. So, rather than try to figure it out, I decided to go the next step. And that next step is to try and figure out why the AS/400 wasn't responding. And pure and simple, the AS/400 was ignoring those packets. Here's the trace: 10.10.10.104 --> 184.108.40.206 (initial request) 220.127.116.11 --> 10.10.10.103 (request forwarded to AS/400) (delay) 10.10.10.104 --> 18.104.22.168 (initial request) 22.214.171.124 --> 10.10.10.103 (request forwarded to AS/400) (delay) That goes on until the browser times out. Remember, communications work fine on the intranet, and if I watch the communications, it's fine: 10.10.10.104 --> 10.10.10.102 (request) 10.10.10.102 --> 10.10.10.104 (response) So, the issue seems to be that the AS/400 doesn't want to communicate with the external address. Now, where in the world is this configured? Due to a different problem (which I'll outline when I get a chance), I did a RMVTCPTBL TBL(*ALL), so that should have gotten rid of any latent IP filtering. So where else is IP filtering defined? In the HTTP configuration? In the line description? WHERE??!?!?!? <sigh> Thanks a million for listening to the frustrations of a beaten man... <wry grin>. +--- | This is the Midrange System Mailing List! | To submit a new message, send your mail to MIDRANGE-L@midrange.com. | To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com. | To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com. | Questions should be directed to the list owner/operator: email@example.com +---
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