From 688ea868f95f3238f7fbb2586beb3e25e6f8f8cb Mon Sep 17 00:00:00 2001 From: Logan oos Even <46396513+Logan007@users.noreply.github.com> Date: Wed, 29 Jul 2020 15:00:26 +0545 Subject: [PATCH] updated Routing.md moved General Remarks from README.md here --- doc/Routing.md | 37 +++++++++++++++++++++++++++++++------ 1 file changed, 31 insertions(+), 6 deletions(-) diff --git a/doc/Routing.md b/doc/Routing.md index 030cbee..8f278ea 100644 --- a/doc/Routing.md +++ b/doc/Routing.md @@ -1,6 +1,29 @@ # IPv4 Routing (Linux) -## Assumptions +## General Remarks + +Reaching a remote network or tunneling all the internet traffic via n2n are two common tasks which require a proper routing setup. n2n supports routing needs providing options for packet forwarding including broadcasts as well as modifying the routing table. + +In this context, the `server` is the edge node which provides access to the remote network/internet, whereas the `client` is the connecting edge node. + +In order to enable routing, the `server` must be configured as follows: + +1. Add the `-r` option to the edge options to enable routing +2. Enable packet forwarding with `sudo sysctl -w net.ipv4.ip_forward=1` +3. Enable IP masquerading: `sudo iptables -t nat -A POSTROUTING -j MASQUERADE` + +On the client side, the easiest way to configure routing is via the `-n` option. For example: + +- In order to connect to the remote network `192.168.100.0/24`, use `-n 192.168.100.0/24:10.0.0.1` +- In order to tunnel all the internet traffic, use `-n 0.0.0.0/0:10.0.0.1` + +10.0.0.1 is the IP address of the gateway to use to route the specified network. It should correspond to the IP address of the `server` within n2n. Multiple `-n` options can be specified. + +As an alternative to the `-n` option, the `ip route` linux command can be manually used. See the [n2n_gateway.sh](doc/n2n_gateway.sh) script for an example. See also the follwing description of other use cases and in depth explanation. + +## Special Scenarios + +### Assumptions - There are two Local Area Networks, namely 10.11.12.0/24 (maybe at **h**ome) and 192.168.1.0/24 (maybe in **o**ffice). @@ -14,7 +37,7 @@ 10.99.99.0/24 network. - The _iptables_ are flushed. -## Prerequisites +### Prerequisites - Both, **h**ickory and **o**scar have ip forwarding enabled: `echo 1 > /proc/sys/net/ipv4/ip_forward` or `sysctl -w net.ipv4.ip_forward=1`. To make this setting persistent over reboot, a file containing the line @@ -25,7 +48,7 @@ interfaces usually already allow packet forwarding and thus do not need any further configuration. -## Reach Complete Office Network from n2n Node at Home +### Reach Complete Office Network from n2n Node at Home - To make **h**ickory send all packets with office destination via **o**scar, **h**ickory needs to be made aware of where to route this @@ -75,14 +98,14 @@ sent to **h**ickory, one more step is required: `iptables -P FORWARD ACCEPT` `iptables -P OUTPUT ACCEPT` -## Reach n2n Node in Office from Whole Home Network +### Reach n2n Node in Office from Whole Home Network This is easy: - Just exchange home and office IP addresses and the computer names in the instructions given above. -## Reach Whole Home Network from Whole Office Network +### Reach Whole Home Network from Whole Office Network This is not too complicated either. Basically, follow the given example above and apply the following changes: @@ -102,7 +125,7 @@ above and apply the following changes: either to the router (best option) or all those computers that shall be able to connect to the other network. -## Route All Internet Traffic from n2n Node at Home through Office Network +### Route All Internet Traffic from n2n Node at Home through Office Network This scenario could be considered a n2n-tunneled VPN connection which also would work for travelling users on their laptop. All external @@ -142,6 +165,8 @@ accordingly, maybe to Google's 8.8.8.8. If [DNS leaks](https://en.wikipedia.org/wiki/DNS_leak) do not matter, this setup is complete. +### Preventing DNS Leaks + Otherwise, there is more to it: Without changes, all future DNS queries go through the home router 10.11.12.1 to the ISP's servers or directly to Google (via the home router 10.11.12.1 along the configured route for