How to find Port number of IP address?

问题:

We can find out IP address of a domain name or URL. But how to find out Port number on which a domain name is hosted?

回答1:

Unfortunately the standard DNS A-record (domain name to IP address) used by web-browsers to locate web-servers does not include a port number. Web-browsers use the URL protocol prefix (http://) to determine the port number (http = 80, https = 443, ftp = 21, etc.) unless the port number is specifically typed in the URL (for example "http://www.simpledns.com:5000" = port 5000).

Can I specify a TCP/IP port number for my web-server in DNS? (Other than the standard port 80)

回答2:

DNS server usually have a standard of ports used. But if it's different, you could try nmap and do a port scan like so:

> nmap 127.0.0.1

回答3:

The port is usually fixed, for DNS it's 53.

回答4:

Port numbers are defined by convention. HTTP servers generally listen on port 80, ssh servers listen on 22. But there are no requirements that they do.

回答5:

If it is a normal then the port number is always 80 and may be written as http://www.somewhere.com:80 Though you don't need to specify it as :80 is the default of every web browser.

If the site chose to use something else then they are intending to hide from anything not sent by a "friendly" or linked to. Those ones usually show with https and their port number is unknown and decided by their admin.

If you choose to runn a port scanner trying every number nn from say 10000 to 30000 in https://something.somewhere.com:nn Then your isp or their antivirus will probably notice and disconnect you.

回答6:

Use of the netstat -a command will give you a list of connections to your system/server where you are executing the command.

For example it will display as below, where 35070 is the port number

 TCP    10.144.0.159:**52121**    sd-s-fgh:35070   ESTABLISHED

回答7:

 domain = self.env['ir.config_parameter'].get_param('web.base.url')

I got the hostname and port number using this.