SPI Firewall Issue... Does Verizon provide public IPs or private NAT to phones?
I am troubleshooting a DroidX that has been having IMAP issues with a mail server ever since an SPI (stateful packet inspection) firewall was put in place. The problems usually surface overnight, and it has recently come to my attention that the IP address of the phone changes overnight. In trying to determine what might lead to the behavior I am seeing (other than a problem in the firewall's configuration, which I have been actively pursuing for some time), it occurred to me that if the DroidX is getting assigned a private IP that is NAT-ed, then the nightly public IP change might be transparent to the DroidX, leading to packets that the firewall sees as having an invalid state (because technically, they would, as there would not have been existing session with the new IP).
In attempting to determine what IP the DroidX sees, I came across this thread: http://www.droidforums.net/forum/tech-issues-bug-reports-suggestions/8603-ip-address.html However, I don't know whether that app, myip actually pulls the IP address out of the nether-regions of the phone or simply gets it from a service similar to whatismyip.com (which would show the NAT-ed address). I didn't find any threads that were more helpful or descriptive.
Anyway, I thought I would see if anyone could tell me for sure what address the Droid OS actually sees rather than downloading an app that may not help onto this phone (that isn't mine). Then, assuming the phone sees an Internet address, which it would know has changed, there might be a bug to report in that maybe existing sessions shouldn't carry over to a new IP and new sessions should be created. I say this because the DroidX worked fine on IMAP before the SPI firewall, and I am operating under the assumption that the communication after the IP change was met with a TCP RST (I know the firewall is dropping the packet instead of sending a TCP RST, hence my assumption), which wouldn't really be necessary if the DroidX knows it has a new IP address.
Thanks in advance to anyone who can help me sort through this. Also, let me know if more details are necessary.