RTSP Port Forwarding

README.md

之前在这里研究过的用iptables配置跨网段的端口转发

Assume we have the following network environments:

• Device:
  • eth0 (192.168.6.59): for external access
  • enx000ec6a490c5 (192.168.1.2): for ip camera
• IP Camera：192.168.1.10
• PC：192.168.6.2

On Device, we want to forward the 554 port (used for RTSP) in ip camera (192.168.1.10) to the same port in 192.168.6.59.

1. Run script/enable_port_forwarding.sh

   #!/usr/bin/env bash
   
   enable_forwarding () {
     ip=$1
     port=$2
     nic=$3
   
     # forward traffic from interface eth0 (public ethernet) and port 554 to the ip camera (192.168.1.10:554)
     sudo iptables -t nat -A PREROUTING -p tcp -i ${nic} --dport ${port} -j DNAT --to-destination ${ip}:${port}
     sudo iptables -t nat -A PREROUTING -p udp -i ${nic} --dport ${port} -j DNAT --to-destination ${ip}:${port}
   
     # accept traffic from ip camera
     sudo iptables -A FORWARD -p tcp -d ${ip} --dport ${port} -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
   }
   
   # parameters
   INTERNAL_IP=192.168.1.10 # for IP camera connected to Host
   PUBLIC_NIC=eth0 # for NIC connected to Internet
   # enable ipv4 forwarding in system side
   sudo sysctl net.ipv4.ip_forward=1
   # flush existed rules of iptables
   sudo iptables -F
   sudo iptables -t nat -F
   sudo iptables -X
   # enable port forwarding
   enable_forwarding ${INTERNAL_IP} 80 ${PUBLIC_NIC}
   enable_forwarding ${INTERNAL_IP} 554 ${PUBLIC_NIC}
   # enable routing
   sudo iptables -t nat -A POSTROUTING -j MASQUERADE

2. You can use the following command to play forwarded RTSP stream on PC:

   ffplay -hide_banner -rtsp_transport tcp "rtsp://192.168.6.59:554/user=admin&password=&channel=1&stream=0.sdp?"
   

3. But you still need to use the original url (like rtsp://192.168.1.10:554/user=admin&password=&channel=1&stream=0.sdp?) to receive video stream on Device.

This is useful, thanks! Do you know why -rtsp_transport tcp is required and whether there is a way to do it without?

For anyone finding this and wondering how to get UDP transport to work, here is my updated fork of this gist:
https://gist.github.com/julianoes/0555ee982991fe97e5a4c2b11316195f