I am trying to find out if it is possible to redirect the traffic of several Android systems on my WLAN to specific internal hosts using IPFW. It seems Android hardcodes specific NTP servers and does not honor the "ntp-servers" DHCP option, meaning I have to allow NTP traffic outbound for these devices to be happy. I have an internal NTP server listening on the WLAN gateway machine, so I want to grab all outbound NTP traffic from internal NAT'ed systems to the WAN and force those packets over to the internal NTP server, AND rewrite the destination address in the packet header.
ipfw's
ipfw's
fwd directive seems like it does all of this EXCEPT rewriting the destination address in the packet header. Is there some other piece of ipfw that will accomplish this by itself or combined with an ipfw fwd rule? I looked at the in-kernel's NAT's redirect_port parameter, but my reading of the man page indicates it is intended primarily for redirecting ports from external to internal, not the other way around. I also can't find an explanation of what the "aliasIP" or "remoteIP" optional parameters to it are for (they're not documented in the man page as far as I can tell).