Setting option 252

Andrew Wood andrew at
Fri Sep 6 12:44:04 UTC 2013

Is it possible with ISC DHCPD to set option 252 to give a PAC file to a 
client to set a web proxy server? I can find some examples of it online 
yet I cannot get it to work with version 4.2 by setting this in the 
global section of dhcpd.conf:

option web-proxy code 252 = text;

and this in the subnet section:

option web-proxy "\000";

Why has an official option to do this never been added to the DHCP 
standard. There are loads of offical options defined in the RFCs for 
setting all manner of things, a lot of which Im sure 99% of people are 
never going to use these days yet something like setting an HTTP/HTTPS 
proxy cant be done exept for an unofficial Microsoft kludge which is not 
supported by all clients or servers. Surely these days this has got to 
be one of the more common requirements. For example we run a public Wifi 
network behind a proxy and need to be able to set HTTPS traffic to be 
CONNECT tunnelled through it as interception can only be done for 
ordinary HTTP. As its BYOD we cannot be manually configuring everyones 

Has this ever been proposed to the IETF does anyone know?

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