distccd

Start a daemon with the default settings

$ distccd --daemon

$ distccd --daemon --allow-private

$ distccd --daemon [[-a|--allow]] [ip_address|network_prefix]

$ distccd --daemon [[-j|--jobs]] [4] [[-N|--nice]] [5]

$ distccd --daemon --zeroconf

distccd [OPTION]…

--allow HOST
    Allow jobs from this host/IP/mask/netgroup (repeatable)

--blacklist HOST
    Deny jobs from this host/IP/mask/netgroup

--daemon
    Fork into background (default unless --no-daemon)

--listen ADDR
    Bind to this address (default all interfaces)

--log-file FILE
    Log to this file (default stderr)

--log-level LEVEL
    Set verbosity: critical|error|warning|notice|info|debug

--no-compression
    Disable compression of job data

--port PORT
    Listen on this TCP port (default 3632)

--user USER
    Drop privileges to run as this user/group

--verbose
    Increase log verbosity

--version
    Print version and exit

-h, --help
    Show help

distccd is the server daemon for distcc, a distributed compilation system that speeds up C, C++, and other compilations by spreading jobs across multiple machines on a network.

It listens on a TCP port (default 3632) for requests from distcc clients, which send preprocessed source code. distccd then compiles the code locally using the system's compiler (gcc, clang, etc.), performs assembly, and returns the object file to the client.

Linking remains local to avoid inconsistencies. This enables massive parallel builds on clusters or farms, ideal for large projects like Linux kernel or Chromium.

Key benefits include near-linear speedup with more hosts, low network overhead (compressed CPP output), and simplicity—no shared filesystem needed. However, all hosts must have identical compiler/toolchain versions.

Security is critical: by default, it allows all clients, so use --allow or firewalls to restrict access. Logs help monitor activity.

Insecure by default: accepts jobs from any host unless restricted with --allow. Use firewalls. Identical compilers required across hosts. High load possible without limits. Not for untrusted networks.

Run as non-root with --user. Restrict with --allow 192.168.0.0/24. Use TCP wrappers or iptables. Monitor logs for unauthorized access.

Use fast LAN; enable compression unless bandwidth-limited. Match distcc version across cluster. Test with distcc -jN make.

Developed in 2002 by Martin Pool as open-source (GPL) to accelerate Gentoo Linux builds. Gained popularity for kernel compilation. Maintained by distcc community; latest stable 3.4.x integrates better with modern build systems like Ninja.

distcc(1), ccache(1), make(1), gcc(1)