Port 774 holds a peculiar place in networking history—it was assigned to two different services depending on which protocol and operating system you were using. Both services are now essentially obsolete, replaced by more modern authentication mechanisms.
What Ran on Port 774
rpasswd (TCP/774)1 was a remote password changing service for Unix systems. It allowed users to change their passwords on a remote server over an SSL connection. A normal user could change their own password, but with the administrator's credentials, any account password could be changed.
acmaint-dbd (UDP/774)2 (originally acmaint_dbd) was Apple's account maintenance daemon for Mac OS X, part of the NetInfo RPC-based services infrastructure. It handled remote procedure calls related to user and account management functions.
The dual assignment reveals how chaotic early port management was—different organizations used the same port number for different purposes, and IANA documented both.
The History
Port 774 first appears in RFC 1340 from July 1992, assigned to rpasswd for TCP and acmaint_dbd for UDP.3 This was before the formalization of port assignment procedures that came with RFC 6335 in 2011.
IANA later renamed acmaint_dbd to acmaint-dbd to conform to well-formed service naming conventions (hyphens instead of underscores).2 The old entry is now marked as historic and not usable with many common service discovery mechanisms.
Why These Services Disappeared
Both services were replaced by more secure, standardized authentication protocols:
- rpasswd was superseded by Kerberos password changing protocols and SSH-based password management tools that provide better security and encryption
- acmaint-dbd became obsolete when Apple deprecated NetInfo in favor of Open Directory and other modern directory services
Security Concerns
Some security databases note that port 774 has been used by malware in the past.4 This is common for abandoned well-known ports—once legitimate services stop using them, they become attractive to malicious actors because they're less likely to be monitored.
What Range This Port Belongs To
Port 774 is in the well-known ports range (0-1023). These ports are assigned by IANA for standardized services and typically require administrative privileges to bind to on Unix-like systems.
The well-known range was meant to be the stable foundation of Internet services—the ports everyone could depend on. Port 774 shows that even within this protected range, services come and go as technology evolves.
Checking What's Listening
To see if anything is listening on port 774:
On modern systems, you'll likely find nothing. Both services are historical artifacts.
Related Ports
- Port 106 - Used by older Mac OS password servers
- Port 464 - Kerberos password changing (kpasswd), the modern replacement for rpasswd
- Port 389 - LDAP, which replaced NetInfo and other proprietary directory services
Why This Port Matters
Port 774 is a reminder that the well-known ports range isn't eternal. Services get assigned, become critical infrastructure, then disappear completely as technology moves forward. The dual assignment also shows how the Internet evolved from a collection of different organizations doing their own thing to a more coordinated system with formal procedures.
IANA's renaming of acmaint_dbd to acmaint-dbd in the registry—just to fix an underscore—demonstrates the level of care that eventually went into maintaining the port number system, even for services that no longer mattered.
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