896206 - DNS leak with local proxy on FTP requests

Status: RESOLVED INCOMPLETE

(Core :: Networking, defect, P5)

Description

[Georg Koppen]

User Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20100101 Firefox/17.0 (Beta/Release)

Steps to reproduce:

I took a proxy that is listening on 127.0.0.1 for HTTP, HTTPS and FTP and went to http://ip-check.info.


Actual results:

Before bug 887995 landed Wireshark showed DNS requests for ip-check.info.


Expected results:

There should not be any DNS requests visible in my traffic log at all. Two things are noteworthy: 1) That leak does not happen with a remote proxy 2) Using Adblock Plus to block FTP requests (thanks to Karsten Ness for this idea) stops the leaks.

Comment 1

[Georg Koppen]

I forgot to mention that bug 769764 introduced that behavior.

Comment 2

[Patrick McManus [:mcmanus]]

see also 889232 comment 9

Comment 3

[Georg Koppen]

Is there any plan to fix this issue for FF24? This will be the next ESR and some security/anonymity products are using it (e.g the Tor Browser). Not sure if I could help here as bug 769764 is quite involved but if so I'd like to know.

Comment 4

[Patrick McManus [:mcmanus]]

I presume this is a dup of 889232 - this is filed against a broken foxy proxy implementation. am I wrong?

Comment 5

[Georg Koppen]

Alas, you are wrong. This has nothing to do with FoxyProxy. I encountered this problem using the "normal" Firefox network settings (on the preferences pane) and without any extensions installed.

Comment 6

[Patrick McManus [:mcmanus]]

can you reword the problem description for me?

Comment 7

[Patrick McManus [:mcmanus]]

08:42:01 AM) GeKo: mcmanus: Hi! Re: #896206:
(08:42:17 AM) GeKo: Take a proxy that is listening locally (say on 127.0.0.1:4001)
(08:42:36 AM) GeKo: then go to http://ip-check.info and watch your traffic with wireshark
(08:42:48 AM) GeKo: You'll see DNS leaks for FTP requests.
(08:42:51 AM) GeKo: That's it.
(08:43:06 AM) GeKo: That does not happen if you have a remote proxy though.
(08:43:25 AM) GeKo: And blocking FTP requests blocks the leak.
(08:44:11 AM) GeKo: and #887995 "fixes" this... somehow...
(08:44:13 AM) mcmanus: so you use the proxy correctly, you just see some DNS traffic?
(08:44:22 AM) GeKo: yes
(08:44:58 AM) mcmanus: do you mean 887995 causes this?
(08:45:17 AM) GeKo: no, it "fixes" this for some reason
(08:45:53 AM) mcmanus: so the request is really just for a backport of 887995 (or something else to fix it too)
(08:46:23 AM) GeKo: yes
(08:46:49 AM) GeKo: but you said in 887995 that the root cause might be a different thing and I should file a new bug.
(08:47:15 AM) mcmanus: oh I'm sure its different ;) - just trying to understand the trail

Comment 8

[Firefox Bug Husbandry Bot]

Bulk change to priority: https://bugzilla.mozilla.org/show_bug.cgi?id=1399258

Comment 9

[Jens Stutte [:jstutte]]

Bulk-downgrade of unassigned, >=3 years untouched DOM/Storage bug's priority.

If you have reason to believe this is wrong, please write a comment and ni :jstutte.