PBR with netifd

• This how-to provides most common scenarios for PBR (Policy Based Routing) with netifd.
• It contains both IPv4 and IPv6 routing rules to prevent traffic leaks.
• Enable IPv6 NAT or NPT and disable IPv6 source filter if necessary.
• Follow Routing and PBR basics for common routing principles.

• Assign each interface to a separate routing table.
  • It makes netifd create essential rules automatically to simplify the setup.
  • This isolates each default route resolving possible routing conflicts.
• Keep the default route enabled for each upstream interface.
  • Multiple interfaces can be connected and used simultaneously by different clients.
• Do not duplicate static routes in different routing tables.
  • Duplicating the same routes in different tables is redundant and pointless.
  • Avoid adding routes on different interfaces to the same table.
• Create custom routing rules for each assigned routing table.
  • Elevate routing decision on the level of routing rules.
    • Abstract from the contents of routing tables for easier troubleshooting.
  • Use a specific custom priority for each routing rule.
    • A priority of about 30000 can override the main table.
    • A priority of about 40000-80000 follows after the main table.
  • Arrange more specific rules before less specific ones.
    • Remember to prioritize tunnel endpoints and local addresses and subnets.
  • Preferably use the main table only for tunnel endpoints.
  • Optionally use the main table for one of the upstream interfaces.
    • This can be useful in a trivial case to minimize configuration.
    • It makes problematic to utilize high numeric priority values.

Assuming the following setup:

• VPN and WAN - upstream networks
• LAN and DMZ - downstream networks

Prioritize routing LAN to VPN. Route DMZ to WAN by default.

for IPV in 4 6
do
uci set network.lan.ip${IPV}table="1"
uci set network.vpn.ip${IPV}table="2"
uci set network.dmz.ip${IPV}table="3"
uci -q delete network.lan_vpn${IPV%4}
uci set network.lan_vpn${IPV%4}="rule${IPV%4}"
uci set network.lan_vpn${IPV%4}.in="lan"
uci set network.lan_vpn${IPV%4}.lookup="2"
uci set network.lan_vpn${IPV%4}.priority="30000"
done
uci commit network
service network restart

Assuming a working WireGuard site-to-site setup.

Allow default routes via VPN client peer on VPN server. Prioritize routing VPN server LAN to VPN tunnel.

uci add_list network.wgclient.allowed_ips="0.0.0.0/0"
uci add_list network.wgclient.allowed_ips="::/0"
for IPV in 4 6
do
uci set network.lan.ip${IPV}table="1"
uci set network.vpn.ip${IPV}table="2"
uci -q delete network.lan_vpn${IPV%4}
uci set network.lan_vpn${IPV%4}="rule${IPV%4}"
uci set network.lan_vpn${IPV%4}.in="lan"
uci set network.lan_vpn${IPV%4}.lookup="2"
uci set network.lan_vpn${IPV%4}.priority="30000"
done
uci commit network
service network restart

Prioritize routing LAN to VPN. Route LAN to WAN as fallback when VPN is down.

for IPV in 4 6
do
uci set network.lan.ip${IPV}table="1"
uci set network.wan${IPV%4}.ip${IPV}table="2"
uci -q delete network.lan_wan${IPV%4}
uci set network.lan_wan${IPV%4}="rule${IPV%4}"
uci set network.lan_wan${IPV%4}.in="lan"
uci set network.lan_wan${IPV%4}.lookup="2"
uci set network.lan_wan${IPV%4}.priority="40000"
done
uci commit network
service network restart

Route LAN traffic to VPN except destinations matching IP set. Mark LAN traffic with firewall to apply custom routing.

for IPV in 4 6
do
uci -q delete firewall.wan_set${IPV%4}
uci set firewall.wan_set${IPV%4}="ipset"
uci set firewall.wan_set${IPV%4}.name="wan${IPV%4}"
uci set firewall.wan_set${IPV%4}.family="ipv${IPV}"
uci set firewall.wan_set${IPV%4}.match="net"
uci -q delete firewall.lan_mark${IPV%4}
uci set firewall.lan_mark${IPV%4}="rule"
uci set firewall.lan_mark${IPV%4}.name="Mark-LAN-VPN"
uci set firewall.lan_mark${IPV%4}.src="lan"
uci set firewall.lan_mark${IPV%4}.dest="*"
uci set firewall.lan_mark${IPV%4}.ipset="!wan${IPV%4} dest"
uci set firewall.lan_mark${IPV%4}.proto="all"
uci set firewall.lan_mark${IPV%4}.family="ipv${IPV}"
uci set firewall.lan_mark${IPV%4}.set_mark="0x1"
uci set firewall.lan_mark${IPV%4}.target="MARK"
uci set network.lan.ip${IPV}table="1"
uci set network.vpn.ip${IPV}table="2"
uci -q delete network.lan_vpn${IPV%4}
uci set network.lan_vpn${IPV%4}="rule${IPV%4}"
uci set network.lan_vpn${IPV%4}.in="lan"
uci set network.lan_vpn${IPV%4}.mark="1"
uci set network.lan_vpn${IPV%4}.lookup="2"
uci set network.lan_vpn${IPV%4}.priority="30000"
done
uci commit firewall
uci commit network
service firewall restart
service network restart

Route all traffic to VPN except a webserver running in LAN and serving to WAN. Mark the webserver traffic with firewall to apply custom routing.

uci -q delete firewall.lan_web
uci set firewall.lan_web="rule"
uci set firewall.lan_web.name="Mark-HTTPS"
uci set firewall.lan_web.src="lan"
uci set firewall.lan_web.src_mac="00:11:22:33:44:55"
uci set firewall.lan_web.src_port="443"
uci set firewall.lan_web.dest="*"
uci set firewall.lan_web.proto="tcp"
uci set firewall.lan_web.set_mark="0x1"
uci set firewall.lan_web.target="MARK"
for IPV in 4 6
do
uci set network.lan.ip${IPV}table="1"
uci set network.wan${IPV%4}.ip${IPV}table="2"
uci -q delete network.lan_web${IPV%4}
uci set network.lan_web${IPV%4}="rule${IPV%4}"
uci set network.lan_web${IPV%4}.in="lan"
uci set network.lan_web${IPV%4}.mark="1"
uci set network.lan_web${IPV%4}.lookup="2"
uci set network.lan_web${IPV%4}.priority="30000"
done
uci commit firewall
uci commit network
service firewall restart
service network restart

Prioritize routing LAN to OpenVPN. Be sure to declare VPN interface and disable gateway redirection.

for IPV in 4 6
do
uci set network.lan.ip${IPV}table="1"
uci set network.vpn.ip${IPV}table="2"
uci -q delete network.vpn_rt${IPV%4}
uci set network.vpn_rt${IPV%4}="route${IPV%4}"
uci set network.vpn_rt${IPV%4}.interface="vpn"
uci -q delete network.lan_vpn${IPV%4}
uci set network.lan_vpn${IPV%4}="rule${IPV%4}"
uci set network.lan_vpn${IPV%4}.in="lan"
uci set network.lan_vpn${IPV%4}.lookup="2"
uci set network.lan_vpn${IPV%4}.priority="30000"
done
uci set network.vpn_rt.target="0.0.0.0/0"
uci set network.vpn_rt6.target="::/0"
uci commit network
service network restart

Prioritize routing LAN to Tailscale. Override the built-in rules generated by Tailscale.

for IPV in 4 6
do
uci set network.lan.ip${IPV}table="1"
uci -q delete network.lan_vpn${IPV%4}
uci set network.lan_vpn${IPV%4}="rule"
uci set network.lan_vpn${IPV%4}.in="lan"
uci set network.lan_vpn${IPV%4}.lookup="52"
uci set network.lan_vpn${IPV%4}.priority="30000"
uci -q delete network.pbr${IPV%4}
uci set network.pbr${IPV%4}="rule"
uci set network.pbr${IPV%4}.goto="10000"
uci set network.pbr${IPV%4}.priority="1"
done
uci commit network
service network restart

Create prohibitive routes in the target routing table. Assuming the loopback interface is always up and the default route has a lower metric.

for IPV in 4 6
do
uci set network.vpn.ip${IPV}table="2"
uci -q delete network.vpn_ks${IPV%4}
uci set network.vpn_ks${IPV%4}="route${IPV%4}"
uci set network.vpn_ks${IPV%4}.interface="loopback"
uci set network.vpn_ks${IPV%4}.type="prohibit"
uci set network.vpn_ks${IPV%4}.metric="9000"
uci set network.vpn_ks${IPV%4}.table="2"
done
uci set network.vpn_ks.target="0.0.0.0/0"
uci set network.vpn_ks6.target="::/0"
uci commit network
service network restart

Create prohibitive rules overriding the default ones. Prioritize custom rules to override the prohibitive ones.

for IPV in 4 6
do
uci -q delete network.lan_ks${IPV%4}
uci set network.lan_ks${IPV%4}="rule${IPV%4}"
uci set network.lan_ks${IPV%4}.in="lan"
uci set network.lan_ks${IPV%4}.action="prohibit"
uci set network.lan_ks${IPV%4}.priority="32000"
done
uci commit network
service network restart