[tor-relays] Dynamic IP

Tim Wilson-Brown
E: twilsonb@xxxxxxx

Date: Mon, 18 Aug 2014 05:04:31 +0200
From: Sebastian Hahn <mail@xxxxxxxxxxxxxxxxx>
To: tor-relays@xxxxxxxxxxxxxxxxxxxx
Subject: Re: [tor-relays] Dynamic IP
Message-ID: <CD0E96E4-2BFA-4FAA-BC19-C3320AC46F08@xxxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset=us-ascii

Hi Tim,

Sebastien, I run a relay on a machine that has an internal private IP, behind a NAT router with a public IP.

In my experience, I need to specify the NAT router's public IP in the torrc, otherwise tor doesn't include it in the router descriptor it submits to the consensus.

This shouldn't happen typically, Tor tries to learn its IP address by
looking at the traffic it receives.

If that process isn't working for me, is this a bug I should report?

Likely. Can you try again, noting the kind of log messages Tor might
emit?

I apologise, Sebastien, it appears I was not waiting long enough for the router to connect to a directory, then use the headers to find its IP. I had always assumed that the first series of failures to find an IP (before any directories were contacted) was permanent.

This is the debug log output from a secondary test router that I configured on the same IP:

Aug 18 17:47:20.558 [info] {CONFIG} int resolve_my_address(int, const or_options_t *, uint32_t *, const char **, char **)(): Guessed local hostname 'REDACTED.local' resolves to a private IP address (192.168.REDACTED.REDACTED). Trying something else.

Aug 18 17:47:20.558 [info] {CONFIG} int resolve_my_address(int, const or_options_t *, uint32_t *, const char **, char **)(): Interface IP address '192.168.REDACTED.REDACTED' is a private address too. Ignoring.

Aug 18 17:47:20.558 [info] {CONFIG} int resolve_my_address(int, const or_options_t *, uint32_t *, const char **, char **)(): Address 'REDACTED.local' resolves to private IP address '192.168.REDACTED.REDACTED'. Tor servers that use the default DirAuthorities must have public IP addresses.

Aug 18 17:47:20.558 [info] {CONFIG} int router_pick_published_address(const or_options_t *, uint32_t *)(): Could not determine our address locally. Checking if directory headers provide any hints.

Aug 18 17:47:20.558 [info] {CONFIG} int router_pick_published_address(const or_options_t *, uint32_t *)(): Success: chose address '121.REDACTED.REDACTED.REDACTED'.

Once the test router appears in the consensus, I'll make similar changes to the primary router (and it will pick them up on the next restart!)

Tim