Port 696 carries RUSHD—the server daemon for Rush, a priority-based render queue that manages distributed processing for film and video render farms.
If you've ever wondered how animation studios render complex 3D scenes that would take days on a single computer, this is part of the answer. Rush coordinates the work, distributing render jobs across dozens or hundreds of machines, turning impossible deadlines into achievable ones.
What RUSHD Does
RUSHD is the server component of Rush, a network render queue system. When an animator submits a rendering job—say, 1,440 frames for a 60-second animation—Rush breaks that job into smaller pieces and distributes them across available machines in the render farm.
The daemon listening on port 696 handles:
- Job submission from artists' workstations
- Status updates from render nodes as they complete frames
- Priority management when multiple jobs compete for resources
- Resource allocation across the farm
Rush uses both UDP and TCP on port 696, favoring UDP for performance—because when you're coordinating hundreds of machines, every millisecond of overhead matters.1
The Problem It Solves
Rendering is embarrassingly parallel. Each frame of an animation can be rendered independently of the others. But someone needs to coordinate the work—who renders what, in what order, with what priority.
Rush solves this without requiring a complex database or heavyweight infrastructure. It's designed to be lightweight and fast, which matters when you're managing thousands of render tasks across a network that needs to stay responsive.2
The architecture is deliberately simple: a client submits jobs, the daemon (rushd) on port 696 manages the queue, and render nodes pull work and report results. This simplicity has kept Rush relevant for over two decades in an industry where tools come and go quickly.
History and Context
Rush was created by Greg Ercolano in the early 2000s for film and video production environments. It's maintained by Seriss Corporation and has been used in visual effects and animation studios for managing render farms since the early days of computer-generated imagery in film.3
The choice of port 696 in the well-known range (0-1023) reflects when it was created—a time when getting an official IANA port assignment was still relatively common for specialized industry tools. Today, most new applications use ports in higher ranges.
Security Considerations
Port 696 should only be accessible within your render farm network. RUSHD is designed for trusted environments—studios where all the machines are under your control and the network is isolated from the Internet.
Do not expose port 696 to the Internet. There's no reason for render farm management to be publicly accessible, and doing so would allow anyone to submit jobs to your render farm or potentially disrupt ongoing work.
If you see unexpected traffic on port 696 and you're not running a render farm, investigate immediately. This port has a specific purpose and shouldn't be active on typical workstations or servers.
Checking What's Listening
On Linux or macOS:
On Windows:
If something is listening on port 696, it should be the rushd daemon on a render farm server. If you're not running Rush and something is using this port, that's worth investigating.
Why This Port Matters
Port 696 represents a category of ports that most people never encounter but that are essential to specific industries. Render farms are how the film and visual effects industry makes the impossible possible—creating imagery that would take years on a single computer by distributing the work across hundreds of machines.
Every frame of CGI you've seen in a modern film passed through something like Rush. The daemon on port 696 isn't glamorous, but it's part of the infrastructure that makes modern filmmaking work.
The port itself is a reminder that the Internet and its protocols serve countless specialized purposes beyond web browsing and email. Somewhere right now, on port 696, a render farm is churning through frames for a film you'll see next year.
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