Re: [tor-dev] DNS resolution isolation in Tor Browser

On 15 Jun 2018, at 09:16, nusenu nusenu-lists@riseup.net wrote:

Thanks for the replies.

Does tor simply assume (try) that the exit policy allows the destination address (not the port) or does it check the exit policy before selecting the circuit? (in that case it would have to know the destination IP before building or at least selecting the circuit to use)

Most tor clients use microdescriptors, which only contain a port summary: https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n1494

Clients check the port, and assume that the DNS name will resolve to an IPv4 address allowed by the exit.

T