The default ports are:
ssh, sftp = 22 (Secure Socket Shell, Secure File Transfer Protocol)
http = 80, 8080 (Hyper Text Transfer Protocol)
https = 443 (Hyper Text Transfer Protocol Secure)
RDP = 3389 (Remote Desktop Protocol)
SMTP = 25 (Simple Mail Transfer Protocol)
FTP = 20, 21 (File Transfer Protocol)
TELNET = 23
IMAP = 143 (Internet Message Access Protocol)
DNS = 53 (Domain Name System)
DHCP = 67, 68 (Dymanic Host Configuration Protocol)
POP3 = 110 (Post Office Protocol Version 3)
DNS Checker:
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