China Internet access mode, Generally, the structure is as follows:

company enterprise network-1

home application for broadband access

ADSL-2

FTTB-3

wired connection-2

metropolitan area network-1

school campus network

campus ADSL-2

pass. If you are LowID, it is basically because of the firewall.

situation 3: you are not sure whether you have a public IP.

users of external networks (public networks) usually dial up to access the Internet through ADSL, wired communication and telephone lines. Whether an access device (Modem) dials or not is the main behavior to distinguish whether it is a public IP in most cases (it is almost impossible for ordinary users to have a fixed Internet IP address). After dialing, you will apply for a temporary Internet IP address at your ISP(Internet Service Provider). For enterprises (some Modem don't need to dial manually in the system) to connect to the Internet. That is to say, an ADSL broadband is only used by a single computer.

what is public network and intranet

Public network and intranet are two ways to access the Internet.

intranet access mode: the IP address obtained by the computer accessing the Internet is a reserved address on Inetnet, and the reserved address has the following three forms:

1.x.x.x

172.16.x.x to 172.31.x.x

192.168.x.x

intranet. Computers in the intranet can send connection requests to other computers on the Internet, but other computers on the Internet cannot send connection requests to computers in the intranet.

public network access mode: the IP address obtained by the computer accessing the internet is a non-reserved address on Inetnet. Computers in the public network and other computers on the Internet can access each other at will.