1 Filename: 118-multiple-orports.txt
2 Title: Advertising multiple ORPorts at once
12 This document is a proposal for servers to advertise multiple
13 address/port combinations for their ORPort.
17 Sometimes servers want to support multiple ports for incoming
18 connections, either in order to support multiple address families, to
19 better use multiple interfaces, or to support a variety of
20 FascistFirewallPorts settings. This is easy to set up now, but
21 there's no way to advertise it to clients.
23 New descriptor syntax:
25 We add a new line in the router descriptor, "or-address". This line
26 can occur zero, one, or multiple times. Its format is:
28 or-address SP ADDRESS ":" PORTLIST NL
30 ADDRESS = IP6ADDR / IP4ADDR
31 IPV6ADDR = an ipv6 address, surrounded by square brackets.
32 IPV4ADDR = an ipv4 address, represented as a dotted quad.
33 PORTLIST = PORTSPEC | PORTSPEC "," PORTLIST
34 PORTSPEC = PORT | PORT "-" PORT
36 [This is the regular format for specifying sets of addresses and
41 We add two more options to supplement ORListenAddress:
42 ORPublishedListenAddress, and ORPublishAddressSet. The former
43 listens on an address-port combination and publishes it in addition
44 to the regular address. The latter advertises a set of address-port
45 combinations, but does not listen on them. [To use this option, the
46 server operator should set up port forwarding to the regular ORPort,
47 as for example with firewall rules.]
49 Servers should extend their testing to include advertised addresses
50 and ports. No address or port should be advertised until it's been
51 tested. [This might get expensive in practice.]
53 New authority behavior:
55 Authorities should spot-test descriptors, and reject any where a
56 substantial part of the addresses can't be reached.
60 When connecting to another server, clients SHOULD pick an
61 address-port ocmbination at random as supported by their
62 reachableaddresses. If a client has a connection to a server at one
63 address, it SHOULD use that address for any simultaneous connections
64 to that server. Clients SHOULD use the canonical address for any
65 server when generating extend cells.
69 * There's no reason to listen on multiple dirports; current Tors
70 mostly don't connect directly to the dirport anyway.
72 * It could be advantageous to list something about extra addresses in
73 the network-status document. This would, however, eat space there.
74 More analysis is needed, particularly in light of proposal 141
75 ("Download server descriptors on demand")
79 Testing for canonical connections needs to be implemented before it's
80 safe to use this proposal.
84 - Write up the simple version of this. No ranges needed yet. No
85 networkstatus chagnes yet.