# A Multi-Path Bidirectional Layer 3 Proxy ## Setup Notes ### Linux #### Policy Based Routing ip route flush table 10 ip route add table 10 to 1.1.1.0/24 dev eth1 ip rule add from 1.1.1.4 table 10 priority 10 ip route flush table 11 ip route add table 11 to 1.1.1.0/24 dev eth2 ip rule add from 1.1.1.5 table 11 priority 11 #### ARP Flux sysctl -w net.ipv4.conf.all.arp_announce=1 sysctl -w net.ipv4.conf.all.arp_ignore=1 See http://kb.linuxvirtualserver.org/wiki/Using_arp_announce/arp_ignore_to_disable_ARP ### Setup Scripts These are functional setup scripts that make the application run as intended on Linux. ### Remote Portal #### Pre-Start #!/bin/bash set -e ## Set up variables REMOTE_PORTAL_ADDRESS=A.B.C.D ## IPv4 Forwarding sysctl -w net.ipv4.ip_forward=1 sysctl -w net.ipv4.conf.eth0.proxy_arp=1 ## Transfer the local routing table to a much lower priority (ip rule show | grep '20:') > /dev/null || ip rule add from all table local priority 20 ip rule del priority 0 2> /dev/null || true ## Ports to route locally ### MPBL3P ip rule del priority 1 2> /dev/null || true ip rule add to "$REMOTE_PORTAL_ADDRESS" dport 1234 table local priority 1 ### SSH ip rule del priority 2 2> /dev/null || true ip rule add to "$REMOTE_PORTAL_ADDRESS" dport 22 table local priority 2 #### Post-Start #!/bin/bash set -e ## Set up variables REMOTE_PORTAL_ADDRESS=A.B.C.D ## Tunnel addr/up ip addr add 172.19.152.2/31 dev nc0 ip link set up nc0 # Route packets to the interface but not for nc via the tunnel ip route flush table 19 ip route add table 19 to "$REMOTE_PORTAL_ADDRESS" via 172.19.152.3 dev nc0 ip rule del priority 19 2> /dev/null || true ip rule add to "$REMOTE_PORTAL_ADDRESS" table 19 priority 19 ### Local Portal #### Pre-Start #!/bin/bash set -e ## Set up variables GATEWAY_INTERFACE=eth0 GATEWAY_ADDRESS=10.36.12.1 ## Fix ARP sysctl -w net.ipv4.conf.all.arp_announce=1 sysctl -w net.ipv4.conf.all.arp_ignore=1 ## IPv4 Forwarding sysctl -w net.ipv4.ip_forward=1 ## Gateway Interface Setup ip addr flush dev "$GATEWAY_INTERFACE" ip addr add "$GATEWAY_ADDRESS"/32 dev "$GATEWAY_INTERFACE" ip link set up "$GATEWAY_INTERFACE" ## Per-Interface Routing Tables ### 10.10.0.0/24 ip route flush table 10 ip route add table 10 default via 10.10.0.1 ip rule del priority 10 2> /dev/null || true ip rule add from 10.10.0.0/24 table 10 priority 10 ### 192.168.0.0/24 ip route flush table 11 ip route add table 11 default via 192.168.0.1 ip rule del priority 11 2> /dev/null || true ip rule add from 192.168.0.0/24 table 11 priority 11 #### Post-Start #!/bin/bash set -e ## Set up variables REMOTE_PORTAL_ADDRESS=A.B.C.D GATEWAY_INTERFACE=eth0 ## Tunnel Address and Enable ip addr add 172.19.152.3/31 dev nc0 ip link set up nc0 ## Route Outbound Packets Correctly ip route flush table 20 ip route add table 20 default via 172.19.152.2 dev nc0 ip rule del priority 20 2> /dev/null || true ip rule add from "$REMOTE_PORTAL_ADDRESS" iif "$GATEWAY_INTERFACE" table 20 priority 20 ## Route Inbound Packets Correctly ip route flush table 21 ip route add table 21 to "$REMOTE_PORTAL_ADDRESS" dev "$GATEWAY_INTERFACE" ip rule del priority 21 2> /dev/null || true ip rule add to "$REMOTE_PORTAL_ADDRESS" table 21 priority 21 #### Client Connect to `GATEWAY_INTERFACE` and set the IP to `REMOTE_PORTAL_ADDRESS`/32 with a gateway of `GATEWAY_ADDRESS`.