Is it dangerous to open ports?

Related questions

1. What is filtered port in nmap?
2. What is an Nmap scan?
3. What is the difference between filtered ports and closed ports?
4. What is stealth port scan?
5. What is stealth scan in nmap?
6. What is UDP port 80 used for?
7. How scan TCP and UDP ports nmap?
8. Does nmap scan UDP ports?
9. What is meant by filtered port?
10. Is it illegal to scan a network?

Tags

1. #opening
2. #through
3. #attack
4. #exploit
5. #firewall
6. #access
7. #needs
8. #danger
9. #ports
10. #typically
11. #having
12. #router
13. #answer
14. #while
15. #service
16. #using