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Highly optimised ICAP server Integrate, customise & extend to meet your needs

Customised ICAP Server
ICAP servers extend proxy servers by performing specific tasks such as content filtering, virus scanning, translation and more.

CensorNet has developed a proprietary, highly optimised, ICAP server which is a core component in a number of services that are provided by the company and its partners. The ICAP server fully supports the ICAP protocol specified in RFC 3507 and errata, including message previews, 204 responses and request pipelining for increased performance.

CensorNet licenses its ICAP server to 3rd party vendors to integrate into their existing solutions. CensorNet can also build custom ICAP servers and provide a virtual machine or ISO installation image for ease of deployment.

ICAP server features

  • 64-bit Linux architecture
  • Pure C code implementation
  • Real-time FIFO thread scheduling
  • Pipelining for early responses
  • Dynamically sized thread pools
  • Prefix trees for fast lookups
  • Zero-copy policy on data buffers
  • Minimal inter-thread locking
  • Highly optimised DFSA protocol grammar parsers
  • REQMOD, RESPMOD support
  • In the case of a web filtering service, support for multiple 3rd party URL classification engines
  • Efficient log processing
  • Available as a customised virtual appliance

Performance expectations (URL filtering example)

  • Each ICAP instance with 1 CPU core can handle up to 10,000 persistent connections
  • User lookup cache can handled hundreds of thousands of different users
  • URL categorisation ~50,000 transactions per second (2.5GHz x 64 core)


CensorNet invites requests to license and customise the ICAP server for use in your own projects. We offer flexible licensing and delivery models.

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