Initial access (protocols)

Theory

Practice

Well known ports

Common port	Protocol	Description
21/TCP	FTP
22/TCP	SSH
23/TCP	Telnet
53/UDP or 53/TCP	DNS
80/TCP	HTTP
88/TCP	Kerberos
389/TCP	LDAP
443/TCP	HTTPS
445/TCP	SMB
554/TCP	RTSP
1433/TCP	MSSQL
2049/TCP	NFS
3306/TCP	MySQL
3389/TCP	RDP
5585/TCP or 5586/TCP	WinRM