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How to setup your test environment with Vagrant

The instruction below will help you bringing up a virtual lab containing VMs sharing their own private network(s). This assumes you are somewhat familiar with vagrant. This has been tested under OSX but it should work find on Linux too. Please provide feedback or PRs/patches if you find problems. This instructions are for DHCPv4 only, DHCPv6 will follow soon.

Install dependencies

First, install chef-dk from https://downloads.chef.io/chef-dk/ . On OSX you can use brew:

$ brew cask install Caskroom/cask/chefdk

Install vagrant-berkshelf plugin:

$ vagrant plugin install vagrant-berkshelf
$ cd ${PROJECT_ROOT}/vagrant/chef/cookbooks
$ berks install

You might need to disable dhcpserver for vboxnet0 in VirtualBox:

$ VBoxManage dhcpserver remove --netname HostInterfaceNetworking-vboxnet0

Start VMs

To start all the vms:

$ cd ${PROJECT_ROOT}/vagrant/
$ vagrant up

This will bring up the following VMs:

  • dhcpserver: a VM running ISC dhcpd (both v4 and v6) configured with a subnet in the private network space. You can start as many as you want by changing the variable on top of the Vagrantfile.
  • dhcplb: a VM running the dhcplb itself, configured to foward traffic to the above;
  • dhcprelay: a VM running ISC dhcrelay, it intercepts broadcast/multicast traffic from the client below and relays traffic to the above;
  • dhcpclient: a VM you can use to run dhclient, or perfdhcp manually to test things. It's DISCOVER/SOLICIT messages will be picked up by the dhcprelay instance

You can ssh into VMs using vagrant ssh ${vm_name}. Destroy them with vagrant destrory ${vm_name}. If you find bugs in the chef cookbooks or you want to change something there you can test your chef changes using vagrant provision ${vm_name} on a running VM.

Development cycle

Just edit dhcplb's code on your host machine (the machine running VirtualBox or whatever VM solution you are using). The root directory of your github checkout will be mounted into the dhcplb VM at ~/go/src/github.com/facebookincubator/dhcplb.

You can compile the binary using:

$ cd ~/go/src/github.com/facebookincubator/dhcplb
$ go build
$ sudo mv dhcplb $GOBIN

And restart it with:

# initctl restart dhcplb

Logs will be in /var/log/upstart/dhcplb.log (becuase the current Vagrant image uses a version of Ubuntu using Upstart init replacement).

On the dhcpclient you can initiate dhcp requests using these commands:

# perfdhcp -R 1 -4 -r 1200 -p 30 -t 1 -i 192.168.51.104
# dhclient -d -1 -v -pf /run/dhclient.eth1.pid -lf /var/lib/dhcp/dhclient.eth1.leases eth1

You will see:

root@dhcpclient:~# dhclient -d -1 -v -pf /run/dhclient.eth1.pid -lf
/var/lib/dhcp/dhclient.eth1.leases eth1
Internet Systems Consortium DHCP Client 4.2.4
Copyright 2004-2012 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth1/08:00:27:7b:79:94
Sending on   LPF/eth1/08:00:27:7b:79:94
Sending on   Socket/fallback
DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 3 (xid=0xcd1fdb2d)
DHCPREQUEST of 192.168.51.152 on eth1 to 255.255.255.255 port 67
(xid=0x2ddb1fcd)
DHCPOFFER of 192.168.51.152 from 192.168.51.104
DHCPACK of 192.168.51.152 from 192.168.51.104
RTNETLINK answers: File exists
bound to 192.168.51.152 -- renewal in 227 seconds.
^C

And something in the dhcplb logs:

I1125 15:54:11.985895   12190 modulo.go:65] List of available stable servers:
I1125 15:54:11.985943   12190 modulo.go:67] 192.168.50.104:67
I1125 15:54:11.985953   12190 modulo.go:67] 192.168.50.105:67
I1125 15:54:16.532833   12190 glog_logger.go:91] client_mac: 08:00:27:7b:79:94, dhcp_server: 192.168.50.104, giaddr: 192.168.51.101, latency_us: 112, server_is_rc: false, source_ip: 192.168.50.101, success: true, type: Discover, version: 4, xid: 0xcd1fdb2d
I1125 15:54:16.534310   12190 glog_logger.go:91] client_mac: 08:00:27:7b:79:94, dhcp_server: 192.168.50.104, giaddr: 192.168.51.101, latency_us: 117, server_is_rc: false, source_ip: 192.168.50.101, success: true, type: Request, version: 4, xid: 0xcd1fdb2d

ISC KEA's perfdhcp utility comes handy so it's installed for your convenience.

Should you need to change something in the dhcprelay here are some useful commands:

# initctl list
# initctl (stop|start|restart) isc-dhcp-relay
# /usr/sbin/dhcrelay -d -4 -i eth1 -i eth2 192.168.50.104

The relay config is in /etc/default/isc-dhcp-relay.

In general you don't need to touch the dhcpserver but you need to restart it you can use:

# /etc/init.d/isc-dhcp-server restart

The main config is in /etc/dhcp/dhcpd.conf. Subnets are configured like this should you need to change them:

subnet 192.168.50.0 netmask 255.255.255.0 {} 
subnet 192.168.51.0 netmask 255.255.255.0 {range 192.168.51.220 192.168.51.230;}