Latest revision as of 14:59, 6 November 2012

Network
What:
Documenting network stuff at 0x20
Participants:
cedric
Locations:
0x20
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[edit] intro

This page was created for the sole purpose of creating clarity in the networking thingies at 0x20.

[edit] The schema

note: This schema accepts patches. You can find the .dia-file (sudo apt-get install dia) at http://members.0x20.be/cedric/Network_0x20.dia

[edit] Sites

[edit] Whitespace

Whitespace, our hackerspace, has a LAN which connects local machines in the network 172.22.32.0/24. We provide ethernet and Wifi access to connect to the network.

[edit] IBBT

Our friends from IBBT (http://www.ibbt.be) have provided us with a virtual server in their data center, which is awesome! It has a massive internet connection and that is why this server is often referred to as "Big Pipe"<ref>Big pipe server</ref>.

[edit] VPN

To link 2 locations you have 2 options:

1. Provide your own infrastructure: connect the two sites with a physical cable
2. Use existing infrastructure to connect the two sites: connect through the interwebs

For a whole bunch of reasons, option #1 is a bit impractical, so the way to go is through the interwebs. That is exactly what is done between 0x20 and IBBT, we've created a so called Virtual Private Network or VPN, which in this case is nothing more than a point-to-point tunnel over the internet connecting 0x20 and IBBT in the same private network. This setup is documented in project OpenVPN<ref>Project OpenVPN</ref>.

[edit] LAN @ 0x20

I'm currently in the process of creating a new intranet at 0x20 with server Kimball as the central server for DHCP, DNS and Routing.

[edit] Network interfaces on Kimball

Kimball has two network interfaces:

# The primary network interface
# eth0 is the WAN-side of our router and takes an IP from the old 0x20 network over DHCP
auto eth0
iface eth0 inet dhcp

# eth1 is the LAN-side of our router. It has a static ip and currently it uses Soekris as DNS server
auto eth1
iface eth1 inet static
address 172.22.42.1
gateway 172.22.42.1
netmask 255.255.255.0
network 172.22.42.0
broadcast 172.22.42.255
nameserver 172.22.32.14

[edit] Routing Configuration on Kimball

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         soekris.0x20.be 0.0.0.0         UG    0      0        0 eth0
172.22.32.0     *               255.255.255.0   U     0      0        0 eth0
172.22.42.0     *               255.255.255.0   U     0      0        0 eth1

[edit] DHCP Service on Kimball

Kimball is configured to provide Dynamic Host Configuration to hosts on the eth1 (LAN) side of the network. The configuration can be found in /etc/dhcp/dhcpd.conf:

# The ddns-updates-style parameter controls whether or not the server will
# attempt to do a DNS update when a lease is confirmed. We default to the
# behavior of the version 2 packages ('none', since DHCP v2 didn't
# have support for DDNS.)
ddns-update-style none;

# option definitions common to all supported networks...
option domain-name "0x20.be";
option domain-name-servers 172.22.32.14;

default-lease-time 6000;
max-lease-time 7200;

# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;

# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
log-facility local7;

subnet 172.22.42.0 netmask 255.255.255.0 {
        option routers 172.22.42.1;
        option subnet-mask 255.255.255.0;
        option ip-forwarding off;
        range dynamic-bootp 172.22.42.100 172.22.42.200;
        default-lease-time 21600;
        max-lease-time 43200;
}

As you can see, Kimball hosts the 172.22.42.0/24 network and also acts as it's default gateway on 172.22.42.1 which is it's own static address on eth1. At the moment we provide the range 172.22.42.100-172.22.42.200 for DHCP.

I also had to tell dhcpd to listen for DHCP-requests on eth1 instead of on eth0. For this I updated the file /etc/default/isc-dhcp-server:

# Defaults for dhcp initscript
# sourced by /etc/init.d/dhcp
# installed at /etc/default/isc-dhcp-server by the maintainer scripts

#
# This is a POSIX shell fragment
#

# On what interfaces should the DHCP server (dhcpd) serve DHCP requests?
#       Separate multiple interfaces with spaces, e.g. "eth0 eth1".
INTERFACES="eth1"

[edit] References

<references/>