Connect to internet DVR via squid+iptables?

Question

linux

There are Dahua video recorders of the same brand in several offices connected to the Internet. All work and show. At the main office, the Internet is connected via iptables+squid (opaque proxy). It is armed through a separate computer connected directly to the router. There was a need to view these cameras to the management.
When trying to authorize through IE, we successfully see the login and password window for the user to enter, but when we enter the correct data, we get the answer: "Login failed". I can't understand why this is happening.
Tried to use SmartPSS but it doesn't know how to proxy. Maybe there is a way to pass SmartPSS through the proxy or bypass it.

Answer 1

I screwed up with the settings, it was enough to enter

-A FORWARD -s 192.168.4.3/32 -p tcp -m multiport --ports 37777 -j ACCEPT

Answer 2

Why through a proxy? in iptables, you need to forward the ports just those that you have on the screen, and you will break through smartpss on an external ip.