Port :105CCSO Nameserver

The CCSO Nameserver Protocol—implemented primarily as Qi on the server side and Ph on the client side—was historically used by academic organizations, such as the University of Illinois, to provide a centralized directory service. Running typically on port 105, it enables searching, retrieval, and management of entity information like email addresses, phone numbers, and departmental info.

From a protocol perspective, Qi functions as a plaintext, query-response system. Client requests are sent via TCP or UDP, and contain formatted queries, which the server then processes before returning relevant records. The communication is straightforward but extensible, allowing both simple searches (e.g., by name) and more complex queries.

While once a common campus infrastructure service, Qi/Ph has been largely supplanted by more modern directories such as LDAP and DNS-based services, owing to their richer feature sets, standardization, and security improvements. Still, understanding the protocol is useful when dealing with legacy network environments or during network reconnaissance.