← Port Encyclopedia
991
Port-991
TCP
System Low Risk
Reserved or unassigned port 991 — may appear in network scans as open, closed, or filtered

🔍 How to Scan Port 991

nmap -sV -p 991 target
nmap -sV -sC --script=banner -p 991 target
nc -zv target 991

🛡️ Security Considerations

  • Scan port 991 with nmap -sV to identify the exact service and version
  • If Port-991 is not needed, close or firewall this port immediately
  • Check for default credentials if a management interface runs on this port
  • Use searchsploit port-991 to find known exploits
  • Monitor traffic on port 991 with Wireshark or tcpdump for anomalies
  • Ensure the service is patched to the latest version to prevent known CVE exploitation

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systat
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📍 Nearby Ports

Port 986
Port-986
Port 987
Port-987
Port 988
Port-988
Port 989
Port-989
Port 990
Port-990
Port 992
Port-992
Port 993
IMAPS
Port 994
Port-994
Port 995
POP3S
Port 996
Port-996
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