FTP - TCP 21

Scan for vulnerabilities with Nmap

nmap --script=ftp-* -p 21 <target ip>

Grab FTP banner with nc

nc -nv <target ip> 21

Check if anonymous login is enabled

ftp <target ip> 21
anonymous:anonymous

Bruteforce FTP login with Hydra

hydra -l <username> -P /opt/wordlists/rockyou.txt ftp://<target ip>