Question & Answer
Question
netstat command display tcp6 instead of tcp for Syslog log source connections on port 514 in a QRadar setup sometimes, even though the connections are established over IPv4?Cause
In a QRadar environment, it's common to receive Syslog log sources over port 514 using IPv4. However, a peculiar observation can arise when running the netstat command: instead of seeing tcp for IPv4-based connections, the output lists tcp6.
This behavior might seem counterintuitive, as it suggests that the connections are using IPv6. In reality, this is not necessarily the case. Understanding this discrepancy is critical to ensuring accurate network configuration and verifying that Syslog data is handled as expected in QRadar.
Answer
Seeing tcp6 instead of tcp or tcp4 in netstat on QRadar typically indicates that services are listening on IPv6 sockets, which can also support IPv4 connections. This is common in modern systems where IPv6 is enabled by default. Modern operating systems and applications often use dual-stack sockets, which allow a single listening socket to handle both IPv4 and IPv6 traffic. When a service binds to an IPv6 address, it can also accept connections from IPv4 clients through the IPv4-mapped IPv6 address feature.
The syslog services in QRadar may be configured to listen on dual-stack sockets for compatibility with both IPv4 and IPv6. This approach simplifies configuration and supports environments transitioning to IPv6 while maintaining backward compatibility with IPv4.
Implications:
- The display of
tcp6innetstatdoes not indicate an issue with the QRadar configuration or syslog connections. IPv4 connections are still being handled correctly, even if they are shown as mapped IPv6 addresses. - This is standard behavior in modern network stacks and does not affect the handling of IPv4 traffic. Understanding this behavior ensures confidence in your system's network configuration and log processing capabilities.
Was this topic helpful?
Document Information
Modified date:
10 July 2025
UID
ibm17179577