Port 1935 RTMP · TCP

What runs on port 1935

RTMP: Adobe's real-time messaging protocol, still the de facto ingest format for live streaming. OBS pushes to Twitch, YouTube and your own nginx-rtmp or MediaMTX server over 1935; playback has moved to HLS/DASH over HTTPS. RTMPS (TLS) is on 443 at most platforms.

Software that uses it: OBS Studio (sender) · nginx-rtmp-module · MediaMTX · SRS · Wowza · Twitch/YouTube ingest

Should port 1935 be open?

Internet-facing only with authentication and care. It can be exposed when the service behind it is authenticated, rate-limited and kept up to date; most deployments are better off behind a VPN, an allow-list or a reverse proxy.

• Open only to the sources you expect; an open RTMP ingest will be found and used.

Check port 1935

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :1935'
sudo lsof -i :1935

# from another machine: is it reachable?
nc -zv host 1935
nmap -p 1935 host
curl -v telnet://host:1935      # raw TCP connect test, Ctrl-C to leave

A port that answers from the internet when it should not is the finding; nmap from a machine outside your network (or a VPS) is the honest test, because scans from inside the LAN pass the firewall you are trying to verify.

Allow or block port 1935

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 1935 proto tcp
sudo ufw deny 1935/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 1935 accept
nft add rule inet filter input tcp dport 1935 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 1935 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 1935 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=1935 protocol=tcp accept'

Replace 10.0.0.0/8 with the networks that need access. Allowing by source address is the rule that matters; "allow 1935" with no source is just "open".

Related ports

• 554 RTSP — Streaming control (IP cameras)
• 443 HTTPS — Web over TLS; UDP for HTTP/3 (QUIC)
• 8554 RTSP alt — MediaMTX, cameras

Part of the port number reference. Ports are 16-bit numbers; see also the subnet calculator and the packet decoder, which shows ports inside TCP and UDP headers.

Questions