Tutorial: Allow UDP Multicast and IGMP to Pass Through⁠

Overview⁠

This tutorial guides you through switching from unicast (Access Server's default data transfer) to allowing UDP multicast and IGMP. This is done with the configuration key, vpn.routing.allow_mcast.

Access Server blocks multicast or broadcast traffic. Follow these steps to lift that restriction.

Connect to the console and get root privileges.
Switch to the scripts directory:
```
cd /usr/local/openvpn_as/scripts/
```

Allow UDP multicast and IGMP traffic to pass through:

./sacli --key "vpn.routing.allow_mcast" --value "true" ConfigPut
./sacli start

This setting implements these iptables rules on the VPN server, which is what allows the traffic to pass through:

ACCEPT udp   -- anywhere  base-address.mcast.net/4 udp
ACCEPT igmp  -- anywhere  anywhere
ACCEPT udp   -- anywhere  base-address.mcast.net/4 udp
ACCEPT igmp  -- anywhere  anywhere

To restore the default setting (and again restrict UDP multicast and IGMP traffic):
```
./sacli --key "vpn.routing.allow_mcast" ConfigDel
./sacli start
```

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Tutorial: Allow UDP Multicast and IGMP to Pass Through⁠

Overview⁠

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