Module 20 - Networking - DNSMASQ¶
Historical miniclass
This lesson was recovered from the former Sandia minimega site. It is preserved for reference and may describe obsolete software, operating systems, commands, or external resources. Consult the current documentation before applying it.
Introduction¶
Let's take what we learned and go one step further. Manually specifying IPs is annoying; let's auto configure IPs with dnsmasq.
Clean up¶
Example¶
# minimega -attach
tap create 100 ip 10.0.0.1/24
vm config disk /home/ubuntu/tinycore.qcow
vm config memory 128
vm config net 100
dnsmasq start 10.0.0.1 10.0.0.2 10.0.0.254
vm launch kvm linux[1-10]
vm start all
Explanation¶
Let's break down the new commands.
minimega:/tmp/minimega/minimega$ tap create 100 ip 10.0.0.1/24
2016/08/26 16:36:16 WARN vlans.go:334: Blacklisting manually specified VLAN 100
ubuntu: mega_tap0
In this step we are creating a network into the VLAN 100 network and assign ourselves an ip address of 10.0.0.1 with a CIDR netmask of /24.
This makes it so the server can talk on VLAN 100 and communicate with TCP/IP to VMs in the IP address space of 10.0.0.1-10.0.0.254.
root@ubuntu:~/minimega# ping 10.0.0.95
PING 10.0.0.95 (10.0.0.95) 56(84) bytes of data.
64 bytes from 10.0.0.95: icmp_seq=1 ttl=64 time=1.36 ms
64 bytes from 10.0.0.95: icmp_seq=2 ttl=64 time=0.705 ms
64 bytes from 10.0.0.95: icmp_seq=3 ttl=64 time=0.514 ms
^C
--- 10.0.0.95 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2000ms
rtt min/avg/max/mdev = 0.514/0.861/1.366/0.366 ms
The next new command starts a dnsmasq service on the network tap we created on 10.0.0.1
Which starts handing out IP addresses from 10.0.0.2-10.0.0.254 for any machine that asks for one with DHCP.
Going Further¶
Running multiple DHCP servers on different VLANs
minimega:/tmp/minimega/minimega$ tap create 100 ip 10.0.0.1/24
minimega:/tmp/minimega/minimega$ tap create 101 ip 11.0.0.1/24
minimega:/tmp/minimega/minimega$ dnsmasq start 10.0.0.1 10.0.0.2 10.0.0.254
minimega:/tmp/minimega/minimega$ dnsmasq start 11.0.0.1 11.0.0.2 11.0.0.254
Print running DHCP servers
minimega:/tmp/minimega/minimega$ dnsmasq
host | ID | Listening Address | Min | Max | Path | PID
ubuntu | 0 | 10.0.0.1 | 10.0.0.2 | 10.0.0.254 | /tmp/minimega/dnsmasq_826235649 | 3216
ubuntu | 1 | 11.0.0.1 | 11.0.0.2 | 11.0.0.254 | /tmp/minimega/dnsmasq_264204396 | 3610
Killing dnsmasq servers
minimega:/tmp/minimega/minimega$ dnsmasq kill 0
minimega:/tmp/minimega/minimega$ dnsmasq
host | ID | Listening Address | Min | Max | Path | PID
ubuntu | 1 | 11.0.0.1 | 11.0.0.2 | 11.0.0.254 | /tmp/minimega/dnsmasq_264204396 | 3610
You can start dnsmasq with a configuration file
Set up a static IP allocation for a VM with the MAC address 00:11:22:33:44:55
Add a DNS entry resolving a domain to an IP
Add a DHCP option