Configuration Reference

Configuration Reference

Everything you configure at the container level: environment variables, volumes, ports, capabilities, and sysctls. (The VPN's own behaviour lives in ocserv.conf — see ocserv Configuration.)

Environment variables

These are read by the container's startup scripts (backend-functions) and drive the automatic NAT/forwarding setup. Defaults are the in-image defaults.

Variable	Default	Description
VPN_SUBNET	10.10.10.0/24	IPv4 subnet that gets source-NAT (masquerade) out of the WAN interface. Must match the ipv4-network/ipv4-netmask in your ocserv.conf.
WAN_IF	eth0	The container interface used as the NAT egress (the "outside").
VPN_IF	vpns+	Interface pattern for the tun devices ocserv creates. The trailing + is translated to the nftables wildcard vpns*. Matches device = vpns in ocserv.conf.
IPV6_FORWARD	1	Enable IPv6 forwarding sysctl inside the container.
IPV6_NAT	0	Enable IPv6 masquerade for IPV6_SUBNET. Off by default — see the IPv6 warning below.
IPV6_SUBNET	fda9:4efe:7e3b:03ea::/64	IPv6 ULA subnet to masquerade when IPV6_NAT=1.

About PUID/PGID: this image does not implement LinuxServer-style PUID/PGID user remapping. Setting them has no effect; ocserv drops privileges internally via the run-as-user/run-as-group directives in ocserv.conf.

⚠️ IPv6 caveat

Do not advertise an IPv6 default route (route = ::/0) to clients unless the container actually has working IPv6 egress. By default the Docker bridge has no IPv6 and IPV6_NAT=0, so handing clients an IPv6 address + ::/0 route blackholes their IPv6 traffic (connections hang until they time out and fall back to IPv4).

The maintained samples ship IPv6 off for this reason. To enable it properly you need (1) Docker IPv6 networking on the container's network and (2) IPV6_NAT=1. See Networking NAT and Routing#ipv6.

Volumes

Mount	Purpose
/etc/ocserv	Required. Holds ocserv.conf, the ocpasswd user database, and any certificates you place there. Persist this.
/swag-config (read-only)	Optional. Mount a SWAG config directory here to use its Let's Encrypt certs directly. See Reverse Proxy and Certificates.
/etc/localtime, /etc/timezone (read-only)	Optional. Align container time/logs with the host.

On first start, if /etc/ocserv/ocserv.conf is missing, the container copies a default template into place (see Architecture and Internals#init-config).

Ports

Port	Protocol	Purpose
443	TCP	Primary VPN transport (TLS). Also what camouflage presents as HTTPS.
443	UDP	DTLS transport (faster). Optional — only used if udp-port is set in ocserv.conf.

Map them to whatever host port you like, e.g. 8443:443/tcp. If you run behind another service already on 443 (like SWAG), publish ocserv on a different host port such as 8443.

DTLS in Docker: UDP/DTLS can misbehave behind Docker's userland proxy (reconnect loops). Many deployments run TCP-only (omit udp-port and the UDP port mapping). It's also stealthier for camouflage. See Troubleshooting#dtls--udp-reconnect-loops.

Capabilities, devices, sysctls

Requirement	Why
--cap-add=NET_ADMIN	Configure interfaces, routes, and nftables rules.
--device /dev/net/tun:/dev/net/tun	Create the TUN tunnel device.
--sysctl net.ipv4.ip_forward=1	Forward client traffic to the internet.
--sysctl net.ipv6.conf.all.forwarding=1	Only needed if you actually route IPv6.

--privileged would also work but is not recommended — the three settings above are the least-privilege way to grant exactly what ocserv needs.

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