问题
When I listen on a port on localhost, Windows will popup a dialogue in which the user must add my program to the list of firewall exceptions. This is annoying, and requires administrator-rights, which the user may not have.
Why does Windows do this for loopback connections (127.0.0.1) and is there some trick to prevent this?
回答1:
The answer was to specify:
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Loopback, Port);
instead of
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, Port);
for the listening socket. At first sight this seems to prevent any firewall warnings and doesn't require any rules to be added to the firewall. But I have to do some more extensive testing to be sure this works on all Windows configurations.
回答2:
It does this to prevent people from doing bad things. If a program is accessing something via localhost, it might do things at higher privileges than it might be able to do if it does it via non-localhost.
Example:
- A localhost administrative port
- Applications that only listen to localhost to prevent remote access, file indexing services
- etc.
There is no way to avoid the popup. Otherwise, what would be the use of it? You can, if your program has administrative privileges, add a firewall exception rule, thus preventing this popup.
来源：https://stackoverflow.com/questions/21230691/why-are-localhost-connections-blocked-by-the-firewall