Golang TCP拨号错误：主机已关闭

Question

net.Dial("tcp", "192.168.1.100:3000")

The above call give me dial tcp 192.168.1.100:3000: connect: host is down.

I can successfully ping the endpoint. I wonder what will be the cause of this error. What will be the possible causes of host is down?

Let me provide more details. The endpoint I am dialing to is running mysql server. And I can successfully connect to it with command line. The endpoint is host in a NAS.

Further investigation, I believe the error message is from https://github.com/golang/go/blob/60e3ebb9cba900f7b2f559b472726cee47e823c0/src/net/fd_unix.go#L94

Answer 1

I have found out why. This is because of firewall settings. This situation is caused by using Little Snitch which will check executable has valid code signature or not. If the executable does not have valid code signature, the request is filtered and Little Snitch will return error number 64 which mean host is down in Mac.