to tell the truth, this problem was really make me very confusing, and exactly how to listen to me slowly!
at first the cause of the problem is: the Taiwanese boss can't visit suzhou factory DVR through Internet (3).
at first the solution: check whether can reach the public network routing and change the port mapping. (public unicom) after
tried the above solution found that routing is accessible, port mapping set method is right, no transfer passing by, why suddenly can't use?Then I use the webmaster's home port scanning tool scans found port are all closed, but I really have opened up a few routing port, why test or shut down?To eliminate the problem of the home of webmaster tools I tested a can normal visit HTTP service IP test, findings suggest open port 80, which proves that tool there is no problem, is still the problem on my side.
May be able to change a kind of thinking mode to check the fault point of error, I try to change all the port mapping to telecommunication lines above, then test, found that can normal use.But why can't unicom line?I began to use the following ways to try to solve the fault.
the second solution: one of them (192.168.16.113) DVR one-to-one NAT out directly.
set to end, start to test it, but found that the problem remains.Here, reminds me of the content of the recently popular 2014 net net action (port).So immediately picked up the phone and dialed the telephone of customer manager, for help.But when the query after found that my public IP doesn't even have ports 80 and 8080.This, I feel a bit helpless.Under normal, again how can bad one-to-one NAT is definitely out of, but why this is so special?But under continue to demand China unicom's support, the present and unicom engineer tried the following two ways:
1, replacing a server/host/port mapping, replace a
2 but no one available with the public IP
perhaps, I do not say, you know, problems still!This is the quiet down and think about the problem really out there!
after about 20 minutes, unicom engineers call let me test need mapping host public IP, when I saw the public IP public IP (telecom), I take a tumble.The cause of the problem is so simple, just because of my carelessness to ignore, I even forget my routing is double WAN!!!!
reason actually very simple, because my routing is double WAN double ISP, without any other routing policy (static routing, policy routing, etc.), under the condition of WAN1 will be set to the default export (I didn't use intelligent load balancing).This means that by default, all packets will pass WAN1 out, unless you manually specify static routing or strategy.
final malfunction: public IP mapping is unicom, but the default data packets through telecommunications export, so lead to cannot reach!
solution: specify the strategy route to 3 DVR hosts use WAN2 (unicom out two) as the default, and map port!
summary: the cause of the problem can only say it's so easy, the main reason is because of carelessness, together with some time ago to add static routing and ignored the problem, lead to the failure.