Firefox's configuration for Remote DNS

This page is obsolete. Torbutton takes care of modifying Firefox settings. (2011-02-13)

Some configurations with Tor are susceptible to DNS leaks, which happen when the client computer accessing the website in question through Tor performs a DNS lookup of the target address, instead of letting the exit node perform the DNS lookup for the address for the client. For this reason, Privoxy is useful for private usage of Tor, however for larger scale usages of Tor, a centralized Tor server would be more appropriate. In this case, it is not necessarily effective to install Tor on every machine planning to use that centralized server, leaving windows where DNS leaks may occur.

Firefox 1.5.0.4 is one of the current browsers that allows configuration for Socks Remote DNS over local DNS resolution. To change this, in Firefox enter 'about:config' in the address bar. Using the filter bar, or scrolling, find the entry 'network.proxy.socks_remote_dns'. Right click the value and select Toggle State. You are now configured to properly use Remote DNS through Socks.

Also, when accessing .onion hidden pages, Firefox needs to be configured to have a longer proxy timeout than normal. Use the above steps to get into about:config, and modify the falue for 'network.proxy.failover_timeout' to be '5000'.

How to prevent any mis-configured app from (even accidentally) trying to resolve any DNS (related to .onion HiddenServices) through direct internet, is described in below page:

DNS Resolver (in [wiki:doc/DnsResolver] page).