← Port Encyclopedia
821
Port-821
TCP
System Low Risk
Reserved or unassigned port 821 — may appear in network scans as open, closed, or filtered

🔍 How to Scan Port 821

nmap -sV -p 821 target
nmap -sV -sC --script=banner -p 821 target
nc -zv target 821

🛡️ Security Considerations

  • Scan port 821 with nmap -sV to identify the exact service and version
  • If Port-821 is not needed, close or firewall this port immediately
  • Check for default credentials if a management interface runs on this port
  • Use searchsploit port-821 to find known exploits
  • Monitor traffic on port 821 with Wireshark or tcpdump for anomalies
  • Ensure the service is patched to the latest version to prevent known CVE exploitation

🔗 Related System Ports

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systat
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Daytime
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📍 Nearby Ports

Port 816
Port-816
Port 817
Port-817
Port 818
Port-818
Port 819
Port-819
Port 820
Port-820
Port 822
Port-822
Port 823
Port-823
Port 824
Port-824
Port 825
Port-825
Port 826
Port-826
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