Stop DHCP INFORM flooding

Background

Windows 7 among others ask for proxy settings using DHCP. The issue is that they do not stop asking until they have received an answer. This results in that the log contains a lot information about these requests, an example can be found below.

Jul 1 06:34:09 MorganB3 dnsmasq-dhcp[1638]: DHCPINFORM(br0) 10.69.10.59 00:23:14:c5:33:fc
Jul 1 06:34:09 MorganB3 dnsmasq-dhcp[1638]: DHCPACK(br0) 10.69.10.59 00:23:14:c5:33:fc MorgansVaioF12Z

This wiki entry describes how to modify the B3 to stop this traffic.

Configuration

No specific configuration information is needed

Packages

No new packages is needed

Setup

Login to the B3 and become the root user

su

Go the the dnsmasq config directory and create a new file

cd /etc/dnsmasq.d
touch no_proxy.conf

Add the following text into the file

# This will tell DHCP clients to not ask for proxy information
# Some clients, like Windows 7, will constantly ask if not told NO
dhcp-option=252,"\n"

Restart DNS

We are now completed so let us restart the server

/etc/init.d/dnsmasq restart

Test

Look at the log, you should only see one more DHCPINFORM entry per computer connected to the B3, then they should stop asking for proxy information.

tail -f /var/log/daemon.log