IANA lists port 1935 as unassigned. The entire live streaming industry disagrees.
Every time you go live on Twitch, push a stream to YouTube, or broadcast from OBS, your video almost certainly leaves your machine on port 1935 via the Real-Time Messaging Protocol (RTMP). The protocol was invented by Macromedia, the company that made Flash. Adobe bought Macromedia in 2005. Adobe killed Flash in 2020. Port 1935 is still running.
What Port 1935 Carries
RTMP is a TCP-based protocol designed for one thing: getting audio and video from a source to a server fast, without dropping frames.
When you configure a streaming encoder — OBS, Streamlabs, ffmpeg, a hardware encoder — you give it two things: an RTMP URL and a stream key. The URL almost always ends in port 1935. The encoder opens a persistent TCP connection to that port and starts pushing chunks of video in real time. The server on the other end — Twitch, YouTube, a Wowza instance, an Nginx RTMP module — receives those chunks, reassembles them, and re-distributes them to viewers.
RTMP itself has variants:
- RTMP — Plain TCP, port 1935. The default.
- RTMPS — RTMP over TLS. Increasingly required by platforms for security.
- RTMPT — RTMP tunneled through HTTP, for networks that block port 1935.
- RTMPE — RTMP with Adobe's proprietary encryption. Largely obsolete.
Why RTMP on Port 1935, Specifically
Macromedia assigned port 1935 when they built Flash Communication Server in the early 2000s. They never formally registered it with IANA — hence the "unassigned" status — but the choice stuck. By the time live streaming became mainstream, every encoder, every server, and every platform had already standardized on 1935. Changing it would mean breaking millions of configurations simultaneously. Nobody wants to do that.
This is how de facto standards work. The port isn't assigned. It's just used. Universally.
RTMP's Peculiar Position in 2026
RTMP is simultaneously obsolete and irreplaceable.
It's obsolete at the viewer end. Browsers can't speak RTMP natively — Flash is gone. Platforms ingest on port 1935 and immediately transcode to HLS or DASH for delivery to viewers. What you send on port 1935 is never what your audience receives.
It's irreplaceable at the encoder end. RTMP is simple, stable, and universally supported. Every encoder speaks it. Every platform accepts it. Newer protocols like SRT and WebRTC offer lower latency and better reliability over bad networks, and they're gaining ground — but they haven't displaced 1935 yet. The inertia is enormous.
Security Considerations
Plain RTMP on port 1935 sends your stream unencrypted. For most streaming scenarios this is fine — you're broadcasting to the world anyway. But your stream key travels in the clear, which means anyone on your network (or watching your traffic) could capture it and stream to your account.
RTMPS (RTMP over TLS, typically on port 443) resolves this. YouTube and Facebook now require RTMPS. Twitch still accepts plain RTMP but supports RTMPS as well.
If port 1935 is open on a server you run, make sure it's intentional. Exposed RTMP servers can be abused to relay unauthorized streams.
What Range This Port Belongs To
Port 1935 falls in the registered ports range (1024–49151). These ports don't require root/administrator privileges to bind, and they're meant to be registered with IANA for specific services. Port 1935's IANA registration simply says "unassigned" — Macromedia's informal claim never became an official registration — but informal consensus in the streaming industry has made it functionally standardized regardless.
How to Check What's Listening on Port 1935
If you're running streaming software — OBS, a media server, Plex — you may well see something on 1935. If you're not and something shows up anyway, investigate.
Frequently Asked Questions
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