What Is a Portscan?
PortscanOverview of Portscan
Portscanning is a network reconnaissance technique used to determine which ports on a system are open, closed, or filtered. Each port corresponds to a specific service or application, such as HTTP on port 80 or SMTP on port 25. By probing these ports, a scanner can identify running services, their versions, and potential vulnerabilities. While portscans are often a legitimate part of security testing and network inventory, they are also commonly used by malicious actors to find exploitable systems.
Why Portscan Detection Is Important
Early detection of port scanning is critical for identifying potentially malicious actors before they attempt an exploit. Security teams use this intelligence to block suspicious traffic, adjust firewall rules, and prioritize incident response. Portscan data can also be correlated with other threat indicators — such as brute-force attempts or known exploit patterns — to create more accurate risk scoring. Because scanning activity often precedes intrusion attempts, identifying it early reduces the window of exposure.
How IPinfo Handles Portscan Context
In addition to collecting outbound IP intelligence like geolocation, ASN, and privacy detection, IPinfo's Probe Network runs passive honeypots — decoy systems configured to appear vulnerable. These honeypots do not respond to normal web traffic; instead, they listen for unsolicited inbound connections, capturing events such as large-scale port scans, brute-force SSH login attempts, and targeted exploits. By aggregating these observations across our globally distributed sensors, we maintain a continuously updated feed of IPs engaged in port scanning. When such behavior is detected, it's assigned the portscan tag.