https://github.com/jech/sroamd

https://github.com/jech/sroamd

Last synced: 5 months ago
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• Host: GitHub
• URL: https://github.com/jech/sroamd
• Owner: jech
• License: mit
• Created: 2021-07-27T12:39:04.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2024-01-22T13:47:04.000Z (over 2 years ago)
• Last Synced: 2025-03-22T20:11:16.516Z (about 1 year ago)
• Language: C
• Size: 42 KB
• Stars: 2
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README

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README

          
Sroamd -- the Simple Roaming Daemon

===================================

Sroamd makes it possible to seamlessly roam between IP links (e.g. WiFi

access points) with no changes to clients.  There is no central controller,

and no tunnelling is involved.

The daemon implements a custom DHCPv4 server, an IPv4 RA server and

a custom peer-to-peer flooding algorithm.  It depends on hostapd for

link-layer configuration, and a routing protocol able to efficiently deal

with host routes (for example Babel).

Usage

-----

Your routers need to all belong to a single routing domain (typically

a single Babel domain with no internal firewalling), but the nodes running

sroamd do not need to be neighbours.  In the following, we assume that

your nodes run Babel over eth0 and use wlan0 as the roaming interface.  We

also assume that you use 2001:db8:4444::/48 and 192.168.44/24 as the

prefixes used for roaming hosts.

### Set up the link layer

Run hostapd on the wlan0 interface.  Your `/etc/hostapd/hostapd.conf`

should say something like

    interface=wlan0

    channel=11

    hw_mode=g

    wmm_enabled=1

    ieee80211n=1

    ssid=sroam

    wpa=2

    wpa_passphrase=topsecret

    wpa_pairwise=CCMP

    

### Set up the IP layer

All of your roaming interfaces must have the same IPv4 address, and they

should have the same IPv6 link-local address.

    ip addr flush dev wlan0

    ip addr add 192.168.44.1/24 dev wlan0

    ip -6 addr flush dev wlan0

    ip -6 addr add fe80::44/64 dev wlan0

    

### Run Babel, redistributing routes to roaming clients

Your routing daemon must be configured to redistribute routes with

protocol 44.  If using babeld, you could say

    babeld -C 'redistribute proto 44 allow' eth0

    

If you're running BIRD, you're on your own.

### Run sroamd

Choose an IPv4 prefix (at least /24) and an IPv6 prefix (at least /56) for

your roaming clients.

  v4prefix=192.168.44.0/24

  v6prefix=2001:0db8:1234::/48

Choose a set of nameservers to advertise to your clients:

  ns1=192.168.43.43

  ns2=2001:0db8:4343::43

Pick one or two stable sroamd instances, call them A and B, to act as

flooding servers:

On A:

  sroamd -P $v4prefix -P $v6prefix -N $ns1 -N $ns2 -f 4444 wlan0

On B:

  sroamd -P $v4prefix -P $v6prefix -N $ns1 -N $ns2 -f 4444 -F A:4444 wlan0

On all other sroamd instances:

  sroamd -P $v4prefix -P $v6prefix -N $nameserver -f 4444 -F A:4444 -F B:4444 wlan0

Notes:

  * you must use the same prefixes (-P) on all instances, but you may use

    different nameservers;

  * the servers need not act as DHCPv4 and RA servers, in which case they

    need not run babeld or hostapd and you should omit the interface name.

### Find the bugs

This is experimental software.  Things will break.