UDP 1604
Synopsis
- Citrix ICA Browser (service name: icabrowser) uses UDP port 1604.
- It’s used by Citrix MetaFrame, Presentation Server, and XenApp (including 5/6/6.5) clients such as Program Neighborhood/PNAgent/older Citrix Receiver to discover servers and enumerate published applications via broadcast.
- Real-world example: In legacy XenApp 6.5 environments, clients send UDP 1604 queries to locate a Zone Data Collector and retrieve the application list; many enterprises historically allowed UDP 1604 between subnets for this purpose.
- Modern Citrix deployments typically use the Citrix XML Service over HTTP/HTTPS instead, so UDP 1604 is mainly seen in older or legacy setups.
Observed activity
Last 30 days
Detailed chart