First, open the port.
To close port 25 of SMTP service in Windows 2000/XP, first open the control panel, double-click the administrative tools, and then double-click the service.
Select the port you want to open. Just select Automatic in the startup type, click OK, then open the service, click Start Enable Port in the service status, and finally click OK.
Second, close the port.
If you close port 25 of SMTP service in Windows 2000/XP, you can do this: first open the control panel, double-click the administrative tools, and then double-click the service.
Then find and double-click the Simple Mail Transfer Protocol (SMTP) service in the opened service window, click the Stop button to stop the service, then select Disable in the Startup Type, and finally click the OK button. In this way, closing the SMTP service is equivalent to closing the corresponding port.
The role of various ports:
Port: 0?
Service: reserved?
Description: Usually used to analyze the operating system. ?
Port: 19
Service: character? generator
Description: This is a service that only sends characters.
Port: 2 1
Service: FTP
Description: FTP server opens ports for uploading and downloading.
Port: 22
Service: Ssh
Description: The connection between TCP established by PcAnywhere and this port may be to find ssh.
Port: 23
Service: Telnet
Description: Telnet remote login.
Port: 25
Service: SMTP
Description: The port opened by SMTP server is used to send mail.
Port: 3 1
Service: msg? certificate
Caption: Trojan horse owner? Heaven, hackers? Heaven opened the port.
Port: 42
Service: win? Separation
Description: WINS replication.
Port: 53
Service: domain name? Name? Server (DNS)
Description: For the port opened by DNS server, intruders may try to pass TCP, cheat DNS(UDP) or hide other communication. Therefore, firewalls usually filter or record this port.
Port: 67
Service: Bootstrap? Agreement? Computer network server
Description: Through DSL and cable? The firewall of modem often sees a lot of data sent to the broadcast address 255.255.255.255.
Port: 69
Service: cumbersome? Documents? transfer
Description: Many servers provide this service together with bootp, so it is convenient to download the startup code from the system.
note:
On Windows? There is no "service" option in 98, which can be set in the rule setting function of the firewall.