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[privoxy-devel] [ ijbswa-Patches-1918189 ] add option to disable DNS lookups
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From: SourceForge.net <no...@so...> - 2012-07-23 06:01:52
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Patches item #1918189, was opened at 2008-03-18 06:47 Message generated for change (Comment added) made by nobody You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=311118&aid=1918189&group_id=11118 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: new feature Group: None Status: Closed Resolution: None Priority: 5 Private: No Submitted By: Max Khon (fjoe) Assigned to: Fabian Keil (fabiankeil) Summary: add option to disable DNS lookups Initial Comment: Privoxy can be deployed in an environment where reverse DNS lookups do not work (neither through /etc/hosts, nor via DNS). This can lead to delays like this: Mar 15 11:31:48 Privoxy(b7e52bb0) Request: foo.com:443/ Mar 15 12:38:25 Privoxy(b7e77940) Error: Unable to get my own hostname: Success Mar 15 12:38:25 Privoxy(b7e52bb0) Request: foo.com:443/ Mar 15 12:42:59 Privoxy(b7e77940) Error: Unable to get my own hostname: Success It is not convenient to require users to modify /etc/hosts (and they not always have permissions to modify /etc/hosts). Attached patch adds configuration option to disable DNS lookups and perform gethostname() instead. Probably the option should have other name. ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2012-07-22 23:01 Message: ZOyH9q <a href="http://yrfznrdvbqrq.com/">yrfznrdvbqrq</a>, [url=http://nvadntlrlxod.com/]nvadntlrlxod[/url], [link=http://zhysiqawpotm.com/]zhysiqawpotm[/link], http://pkkurvupijpt.com/ ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2010-02-06 09:09 Message: Please run the following test: -If there are any DNS caching servers running, shut them down. -This step is optional if you want to see the flood of DNS requests -> capture your traffic with a program like Wireshark -Connect to any website using only Privoxy as the configured proxy in your browser The websites will load so slow it is impossible to do anything. Measuring time and testing with Privoxy and without it, the total load time increases from ~6 seconds to ~58 seconds! Tested here: http://www.skyscrapercity.com/showthread.php?t=419362&page=645 Did I miss a running DNS server as a requirement to run Privoxy? ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2010-02-04 08:46 Message: One big plus of Privoxy I always considered its controllability. With DNS playing such an important role and Privoxy being a proxy, why not add a caching option. As already written, I believe this is a potential bottleneck and not on every system a DNS caching server can be run. What the browser usually does is - again - circumvented by Privoxy and its inability to do any caching. Privoxy is not a SOCKS proxy thus the client is making requests like always but they won't help because it has to go through another layer - Privoxy first. Please revisit this proposal, thank you. ---------------------------------------------------------------------- Comment By: Fabian Keil (fabiankeil) Date: 2009-09-13 08:11 Message: I'm not aware of anyone currently working on DNS caching in Privoxy. I assume that most people who care about DNS caching simply enable it in their libc or use a local DNS server. ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2009-09-12 04:04 Message: Will this proposal be considered or are we never going to see such functionality in Privoxy? ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2009-08-03 12:39 Message: Looking at some traffic with Wireshark, Privoxy is sending a DNS request for every connection it is going to establish. So despite of the software sitting behind Privoxy and using it as a proxy that do hold the hostnames in cache - Privoxy is going to request the hostnames anyway. I will give you an example where this might lead to problems: Say the system does not have any kind of dns caching or server that will respond to the requests of Privoxy locally and all DNS requests will go to the external servers. If the bandwidth of the user's internet connection is being used on a high level thus increasing overall latency due to a continuous up/down-stream of data and making heavily use of the "tabbed browsing" feature - many connections at the same time to different hosts in a short time span, Privoxy might get "stuck" for a bit. This is what will be seen as websites not loading so fast because their hosts are in the progress of being looked up again... and again. That's only one scenario of many and while every more established browser I know of holds some type of short time memory for hostnames, it will be circumvented by Privoxy. So to me it would make good sense to hold a similar cache, configurable. ---------------------------------------------------------------------- Comment By: Fabian Keil (fabiankeil) Date: 2009-05-25 14:17 Message: The hostname option is described at: http://www.privoxy.org/user-manual/config.html#HOSTNAME It has nothing to do with caching, however. If Privoxy's DNS requests to a local DNS server are a bottle neck there's probably something wrong with the DNS server. I'm not sure what you mean by "autonomous lookups", but Privoxy uses the operating system's libc to do DNS lookups, so it's not that autonomous in the first place. Also note that there are extensions that implement DNS caching inside the libc. If you'd use one of those, Privoxy would "profit" from it (unless you have hundreds of users the impact shouldn't be measurable, though). On FreeBSD this is done by nscd(8), you might want to check if something similar is available for your operating system. ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2009-05-12 09:37 Message: Thank you for answering. To be more specific, Implemented but not released? I could not find a sign of it in the documentation nor in any other file. The caching part is already done locally on my machine and for Privoxy a real short cache would suffice. Keeping hostnames from 30 seconds to 5 minutes to prevent a flodding of lookup requests would be a reasonable measure imo to counter potential bottlenecks. In any case the ability to turn off autonomous lookups done by Privoxy altogether would remove the need for said caching. ---------------------------------------------------------------------- Comment By: Fabian Keil (fabiankeil) Date: 2009-05-12 08:55 Message: The hostname option has been implemented as mentioned in the comments below, however Privoxy still doesn't have a DNS cache and there are no intentions to add one. That's what local DNS servers are for. ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2009-05-12 03:39 Message: Has this feature never been implemented and if so, why? I see a massive amount of unnecessary hostname lookups done by Privoxy for multiple connections to the same host where only on the first attempt there should have been a lookup, (missing dns cache?). This effectively doubles the connections made by Privoxy and is producing a lot of overhead. ---------------------------------------------------------------------- Comment By: Fabian Keil (fabiankeil) Date: 2008-03-26 11:09 Message: Logged In: YES user_id=875547 Originator: NO It's available in CVS now. ---------------------------------------------------------------------- Comment By: Fabian Keil (fabiankeil) Date: 2008-03-25 10:25 Message: Logged In: YES user_id=875547 Originator: NO We haven't talked about a release date yet, but hopefully in a few months. However you could always checkout the current version from CVS. I intend to commit the code before the end of this week. ---------------------------------------------------------------------- Comment By: Nobody/Anonymous (nobody) Date: 2008-03-20 11:22 Message: Logged In: NO Thanks! Can you tell me when can I expect Privoxy version with "hostname" option? ---------------------------------------------------------------------- Comment By: Fabian Keil (fabiankeil) Date: 2008-03-20 10:06 Message: Logged In: YES user_id=875547 Originator: NO Thanks for the offer, but I intend to refactor parts accept_connection() anyway and might as well add the hostname option while I'm on it. ---------------------------------------------------------------------- Comment By: Max Khon (fjoe) Date: 2008-03-19 13:20 Message: Logged In: YES user_id=905350 Originator: YES Yes, this would work perfectly for me. Do you want me to make a patch? ---------------------------------------------------------------------- Comment By: Fabian Keil (fabiankeil) Date: 2008-03-19 11:28 Message: Logged In: YES user_id=875547 Originator: NO Thanks for the patch. The problem with using gethostname() is that it might not be available on all platforms (It's "only" IEEE Std 1003.1-2001). Instead of using gethostbyname() I would prefer to have a configuration option that just disables hostname lookups and lets the user specify the "hostname" manually. It would also make changing the displayed hostname more convenient as it wouldn't require root access. Am I right to assume that this would work for you as well? ---------------------------------------------------------------------- Comment By: Max Khon (fjoe) Date: 2008-03-18 06:48 Message: Logged In: YES user_id=905350 Originator: YES Also, there is an entry in FAQ about DNS lookups. Probably the DNS lookups should be turned off by default. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=311118&aid=1918189&group_id=11118 |