Port 1501NetGuard GuardianPro Auth Client
The NetGuard GuardianPro firewall Authentication Client enables secure communication and verification processes between client systems and the GuardianPro firewall on NT4 platforms. Operating mainly over UDP port 1501, it facilitates authentication requests and responses, helping enforce network access control. This service is essential for validating clients before granting protected network access via the GuardianPro security suite..
- transport
- udp
- in transit
- cleartext
- assignment
- unofficial
- risk
- 4/10
- lookups
- 12,017
single transport
payload readable on path
used by convention
caution
rank 327 of 993 · top 33%
Technical Details
what runs on :1501NetGuard GuardianPro's Authentication Client on port 1501 serves as a dedicated communication endpoint for authentication interactions between client devices and the GuardianPro firewall appliance, typically implemented on Windows NT4 infrastructures. It primarily utilizes UDP as the transport protocol, optimized for lightweight and rapid authentication transactions without the overhead of connection-based protocols.
The Authentication Client initiates requests to verify user credentials, device legitimacy, or policy compliance before access is granted to the internal network or protected resources. The communication often follows proprietary protocols specific to the GuardianPro ecosystem, handling token exchanges, session validation, and access grant or denial messages. During the process, it may also interface with internal directory services or credential stores maintained by the firewall.
Because this service is NT4-based, it exhibits legacy system characteristics, such as minimal encryption and deprecated security algorithms by modern standards. Maintenance of this service requires careful network segmentation or compensating security controls due to its outdated technology stack.
Security Information
exposure of :1501risk score
4/ 10caution
worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.
security averages 3.8 across 216 ports — this one sits 0.2 above.
in transit
cleartext
credentials and payloads are readable by anyone on path
assignment
unofficial
used by convention, not registered — what answers here varies by deployment
reachable over
udp
udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite
security overview
Common Vulnerabilities:
- Lack of Encryption: Communications are typically unencrypted, making them susceptible to packet sniffing and credential interception.
- Legacy Protocol Weaknesses: The NT4 environment and legacy protocols may harbor multiple known vulnerabilities exploitable via spoofing, replay attacks, or credential harvesting.
- UDP-based Attacks: The use of UDP increases exposure to spoofing, reflected amplification DDoS attacks, or unauthorized scanning due to the stateless nature of UDP communication.
Common Mitigations:
- Network Isolation: Isolate legacy GuardianPro authentication services on separate network segments or VLANs with strict access controls.
- Ingress Filtering: Implement strict ACLs or firewall rules to restrict incoming requests to known authentic clients only.
- Upgrade and Patch Management: Where possible, migrate away from deprecated NT4 systems and replace GuardianPro with modern, supported solutions.
- Encryption Overlay: Use VPNs or encrypted tunnels to protect authentication exchanges over untrusted networks.
- Monitoring: Employ logging and anomaly detection on UDP 1501 traffic to identify and respond to suspicious activities in real time.
Related Ports
the 8 most looked-up other ports in security — 216 ports carry that label.
| port | service | risk | |||
|---|---|---|---|---|---|
| :8881 | Atlasz Secure Server | TCP | Web Services | caution | 67.6k |
| :443 | HTTPS | TCPtls | Web Services | caution | 65.9k |
| :8291 | Winbox MikroTik Admin | TCP | Security | caution | 62.9k |
| :3268 | Microsoft Global Catalog (GC) | TCPUDP | Security | caution | 54.6k |
| :135 | Microsoft EPMAP | TCPUDP | Security | caution | 51.9k |
| :3128 | Squid Proxy HTTP | TCP | Web Services | caution | 45.8k |
| :8080 | HTTP Alternate | TCPtls | Web Services | caution | 44.9k |
| :7000 | Vuze HTTPS Tracker | TCPtls | Security | caution | 28.9k |
risk mix of the 8 listed
- caution100%
3 of 8 encrypted