DHCP dnsmasq for infinite lease

dhcpdnsmasq

I am using dnsmasq to serve IPs for about 200 vservers.
Leasetime is infinite:
dhcp-range=10.0.1.2,10.0.1.254,infinite

I don't know why, but 1 vserver changed IP. Let's say MAC address changed.

I wanted the vserver to get back his old IP, so i shut down the interface and edited /var/lib/misc/dnsmasq.leases (changed new/old IP)

After reboot vserver had wrong new IP again. So i think /var/lib/misc/dnsmasq.leases is just a log-file?!

I fixed the problem with changing vserver IP on console – after reboot vserver had old IP.

But i want to understand – how does dnsmasq save the information "i want to give this IP to this MAC" and how can i change this?!

Best Answer

The dnsmasq.leases file is like a database for dnsmasq to know what address has assigned along with some other info.

According to sites here and here you cand assign static ip to a host as follows:

--dhcp-host=servername,192.168.0.199
--dhcp-host=00:20:e0:3b:13:af,servername,infinite
--dhcp-host=aa:bb:cc:dd:ee:ff,192.168.0.199

Note: if you use the first option, you have to make sure the hostname of the client machine match with the entry --dhcp-host=servername in your dnsmasq.conf file.

I hope this helps.

Related Solutions

Disable dhcp service in dnsmasq

dnsmasq has dhcp server disabled by default. To enable it you have to uncomment dhcp-related lines in /etc/dnsmasq.conf

to forward all requests to 208.67.222.222 it's sufficient to add (without touching dnsmasq config) in /etc/resolv.conf:

nameserver 127.0.0.1 
# In order to configure dnsmasq to act as cache for the host on which  it
# is  running, put [as the first line] "nameserver  127.0.0.1" in /etc/resolv.conf to force
# local processes to send queries to dnsmasq. [...]
# dnsmasq is smart enough to ignore this line and forward all queries appropriately, 
# while all other applications will send all their queries to dnsmasq. 
nameserver 208.67.222.222

That's it :)

1 Year DHCP Lease – Configuration and Best Practices

Technically there is nothing wrong with this lease time, especially if in the school the computers and devices on the network rarely change. However, the general rule of thumb is that your leases should be long enough to reduced network bandwidth and server load in the event that you have a large amount of devices who could potentially need leases.

So technically, no there is nothing wrong with this, the system is designed to support it, but from a usability and maintenance viewpoint it may get to be confusing and hard to maintain if you have to eventually go in an kill old leases when machines come or go. Especially if you want to make any network changes within a year as well.

In the past I have typically stuck to lease times of about a day but no more than a week. It really isn't that much load and a properly loaded DHCP server or servers should be able to handle that load just fine.

Best Answer

Related Solutions

Disable dhcp service in dnsmasq

1 Year DHCP Lease – Configuration and Best Practices

Related Topic