TL;DR Will OpenBSD policy based routing help with a multi-homed server/gateway situation? If so, how do I configure it?
I'm managing an OpenBSD with two ISP links and VPN tunnels to remote routing nodes.
Initially we used multiple default routes with varying metrics -- the preferred route through a static IP address a NAT router which, in turn has dynamically allocated addresses (it's basically a cable modem).
In practice this was not ideal but it works well enough. New connections established from the gateway (hereinafter referred to simply as 'gw') would select the higher speed, lower latency route if it was up; and go out through the cable modem if the link was down. Inbound connection could only come through the better route since the other IP addresses were behind NAT (not routable from the outside.
Now we need to route traffic through an additional proxy/VPN router nodes out "in the cloud" to mitigate risks DDoS on our static IP addresses.
Those are connecting to the gateway via tunnels.
first. Then we found that our admin access would sporadically drop.
To complicate matters further this gateway has additional active interfaces to specific VLANs. They're unrelated to this problem but can't be disturbed.
It's my impression that we should be using policy based routing, rdomains. I guess that means I create routing tables for each of my three involved interfaces and any connection on any of those (including the tun0 tunnel interface) should be routed through the table for that domain (and thus each can have its own default route).
Am I on the right track?
Here's a diagram and a sanitized list if interface settings:
________ | tunnel | _______ ~~~+~~~~ | GW |======++ | ~+~+~+~ || | _________ | | | || +-----| prefISP |-------------+ | | __||____ ......... ~~~~~~~w~ | +-----| Switch |-----( Cluster ) | ~~~~~~~~ ^^^^^^^^^ _________ .....|...... || | fallISP |---------( LAN / WiFi )===++ ~~~~~~~~~ ^^^^^^^^^^^^ Diagram: I want to avoid asymmetric routing when accessing GW through the tunnel, through the preferred ISP, and when accessing GW or the cluster (through the GW or from the LAN). Sanitized interface info: em3: inet 22.214.171.124 netmask 0xfffffff8 broadcast 126.96.36.199 description: prefISP em0: inet 10.1.1.100 netmask 0xffffff00 broadcast 10.1.1.255 description: fallISP tun0: inet 192.168.2.2 --> 192.168.2.1 netmask 0xffffff00 description: tunnel em1: VLAN_TRUNK vlan1000: inet 172.29.1.1 netmask 0xffffff00 broadcast
As noted: em3 is our link to the preferred (faster) ISP; tun0 goes through it; em0 is on the same segment as the office LAN/Wifi and serves as our fallback ISP; and GW has additional links to the cluster and the switch.