Changes between Version 17 and Version 18 of doc/FAQUnanswered


Ignore:
Timestamp:
Apr 23, 2010, 4:48:47 AM (10 years ago)
Author:
trac
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • doc/FAQUnanswered

    v17 v18  
    11This is a list of questions people wish were answered in the [:../TorFAQ]; please add some more.  Better yet answer one and move it to [:../TorFAQ].  Finally you can vote for a question to be answered by incrementing the number after the question in parens.
    22
    3 '''Please do not report bugs here; instead, use the [https://bugs.torproject.org/flyspray/index.php?tasks=all&project=4 bug tracker].'''  Soon, we'll designate one of the proposed bug servers as official, and you'll be able to post bugs there too.
     3Do I need both Tor AND Privoxy to browse hidden sites? Why? (votes: 1)
    44
    5 Also, this is '''not the place''' for random ''it doesn't work'' or ''how do I do foo'' questions.  Support questions are really better asked and answered on the
    6 [http://archives.seul.org/or/talk/ or-talk mailinglist].  Also, always a good read: [http://www.catb.org/~esr/faqs/smart-questions.html How To Ask Questions The Smart Way].
     5Who's doing this? (votes: 1)
    76
    8 = Unanswered FAQ Questions =
     7Can I help? (votes: 2)
    98
    10 1) '''Hidden services are currently very vulnerable to attacks by web hosts who come to suspect a machine in their network is being used for Tor. Since they can power cycle the server in question (and likely blame it on technical difficulties without arousing suspicion) they can make an unambiguous identification of a hidden service host.
    11 This could be prevented if the directory servers supported more than one provider for a hidden service and so could direct requests away from a non-responsive server (there may be other solutions). Of course this could also help provide more reliable hidden services in general. Is there any chance of this getting implemented in the near future?'''
     9I've got a bug, now what? (votes: 2)
    1210
    13 2) '''Why do I keep getting messages telling me that my clock has just jumped ahead and that my circuits will be assumed broken? ''(eg.
    14 Oct 02 10:14:53.619 [notice] Your clock just jumped 1056 seconds forward; assuming established circuits no longer work.'') I've got a cron job to sync the time every eight hours and it's never out by more than a second.'''
     11So I'm totally anonymous if I use Tor? (votes: 1)
    1512
    16 -- On my system, this happens when Vidalia gets into trouble. It seems that when tor and V communicate, tor can wind up waiting for V to respond, or for the V process to be killed.
     13Where can I learn more about anonymity? (votes: 1)
    1714
     15What attacks remain against onion routing? (votes: 1)
    1816
    19 3)'''If an attacker has access to past logs of ISP and any given visted site, does the prng of the tor client allow the attacker to guess which circuit it used next?'''
     17What projects are comparable? (votes: 1)
    2018
    21 Tor uses cryptographically strong random numbers provided by OpenSSL when choosing nodes to use in a circuit. How OpenSSL implements this is operating system specific. If there's a weakness in Tor's method of choosing nodes, it probably isn't in the random number generator.
     19What's Onion Routing? (votes: 1)
    2220
    23 *** Hmm, if the prng is deterministic, and you can narrow one result of calling it by knowing what host was chosen, can you, knowing the algorithm, however good it is, thereby narrow the result of the next call to it?  This question might be a bit ignorant; for example the prng might use other data on the client computer instead of following an algorithm to return the next item.
     21How does Tor relate to the Freedom Project? (votes: 1)
    2422
    25 *** Thanks for your comments, BTW, as a lot of us are wondering the answers to these FAQU.
     23Protocol and application support - http? ftp? udp? socks? mozilla? (votes: 1)
    2624
    27 *** It has nothing todo with determinism. It is a matter of predictability. Without using real entropy, everything done on conventional computers should be deterministic (try teling that to people who use Windows ;). However, the part that we are interested in is whether someone can predict what Tor is going to next choose.
    28 
    29   Cryptographic number generators have the property that they (shouldn't) give up their internal state by their external outputs quickly. So, unless the attacker gets to see a lot of outputs - node choices - without reseeding from real entropy they are pretty much screwed provided the cryptograpphic prng isn't broken.
    30 
    31 
    32 '''Is there a signal i can send the tor client to tell it to switch circuits immediately?'''
    33 
    34 You can connect to Tor's control port and send "authenticateCRLFsignal newnymCRLF" where CRLF is a carriage return line feed pair.
    35 
    36 '''Why does Firefox/Privoxy/Tor return Privoxy 404 pages so frequently -- almost every time -- when properly configured, even on sites like google.com?  How to mitigate?  The tor process is running fine.'''
    37 (Votes: 2)
    38 
    39 The first problem is that Privoxy doesn't retry in case of
    40 DNS errors. It shows the 404 no such domain message right away.
    41 The second problem is that some browser cache Privoxy's error
    42 messages and Firefox is one of them.
    43 
    44 The Privoxy patch described at
    45 http://www.fabiankeil.de/sourcecode/privoxy/
    46 lets Privoxy retry in case of connection problems
    47 and makes sure, the browser doesn't reuse a cached
    48 error message.
    49 
    50 '''For that matter, why is DNS the main failure mode?  Who is timing out and why?  Can Tor (1) change the timeout, (2) deprecate bad servers, or (3) cache DNS locally so it doesn't have to make a long, slow, failure-prone DNS lookup every time?'''
    51 
    52 You should be sending hostnames to Tor over SOCKS4a or SOCKS5. In that case, the Tor exit node will resolve the hostname before making a connection for you. Unless the exit node is misconfigured, there shouldn't be a problem with DNS resolves timing out.
    53 
    54 *** Actually, for me this happens most of the time.  I am sending through Privoxy, and tried both sockses.  So why would I be hitting so many exit nodes that FREQUENTLY time out on DNS?  Firefox 1.5, most recent stable Tor.
    55 
    56 '''Is the reason that gmail rarely works: gmail, tor, privoxy, firefox, your own bandwidth/latency, tor's bw/latency, or some combination?  Is it fixable?'''
    57 
    58 *** For Gmail for me, it's even worse; I have to try 5 or 6 times before I get a page.
    59 
    60 -- I know that improvements to DNS handling are due in 1.2.x-final (see bug #364).
    61 -- I've just tried a comparison of Firefox loading gmail using privoxy and polipo under Tor 0.1.2.17.  Using privoxy the site did not load, but with polipo it loaded normally.  Can anyone confirm this?
    62 
    63 '''Why is the argument against more than 3 hops that both-ends attacks are the enemy?  Wouldn't it be better to have more than 3 if the enemy cannot mount a both-ends attack?'''
    64 
    65 This is two questions, really.
    66 
    67 To understand it better, think from the perspective of an attacker. They have a choice: they can make a both-ends attack, an attack comprising the hops and both.
    68 
    69 Now, at this point you need to think what attacker you are trying to defend against. The NSA? Sorry, your screwed - find something else. A big company? Some rogue ISP's? Ok, now that's something that Tor may be able to defend against...
    70 
    71 Now, what information are you - the attacker - trying to find? Who is talking to who? Content of some transmissions? Both?
    72 
    73 Well, for finding content of transmissions your best way is to just listen in on some exit nodes.. or create some malicious ones. That's not the attack threat we're trying to defend against, then.
    74 For finding who is talking to who? Ok, let's say that's what we're trying to find out.
    75 
    76 From this perspective, what is needed to mount a both-ends attack? Listening on both ends. If there is some mitigation technique used - like random timing - compromising those both ends could come in handy (at this point, more hops would really be useful). But there isn't - AFAIK - and so we shall suppose that listening on both ends is enough.
    77 
    78 Now, what is the alternative option? Listening to all the hops AS WELL? Oh dear, that's a little harder.. and what does it bring us? Well, we can get slightly more accurate results - maybe - as we can more closely correlate. This, of course, gets yet better if we compromise some of those hops.
    79 
    80 The key word here is slightly. Provided the number of hops is a constant - so you can get a reasonably accurate latency estimate - then, over a longer enough period of time, you will be able to correlate and get your results.
    81 
    82 The key word here is slightly. Provided the number of hops is a constant - so you can get a reasonably accurate latency estimate - then, over a longer enough period of time, you will be able to correlate and get your results.
    83 
    84 So, yes, the hops will make it slightly more secure. But only slightly. And yes, in some cases, it may be really useful.. but in those cases, you probably should be using something with much stronger anonymity than tor (if someone knowing what your saying is unacceptable, don't use tor.. not, at any rate, on it's own).
    85 
    86 Now, then, what are the disadvantages to more hops? More bandwidth is used. Latency is increased.
    87 
    88 Despite this, it's possible that having number of hops as an easily configurable option is not a bad idea... I would guess that there is an excess of middle-man nodes with the recent draconian laws in some parts of the Western oh so free world that make people interested in privacy yet at the same time too scared to actually stick their neck out. In this case, Tor as a network would likely not lose much by doing that.
    89 
    90 *** I ommitted elaboration of the cases where more hops would be really useful (I think I forgot about it..). These cases are generally when traffic originating from an exit node is wanted to be tracked down and a response can be made quickly, but does not have global observer capabilities. In that case, in order to find the entry node, going through each hop is the only sensible solution in a network with > 50 servers. How much you would gain from extra hops is difficult to answer.. it would depend, I think, on how often circuits rotate and the probability of a hop being out of the grasp of the attackers. Hops are, I think, probably most useful when you - or your data - specifically are being targeted..
    91 
    92 '''How can I be sure that sending DNS through tor doesn't get spoofed sites?'''
    93 
    94 Use a method for authenticating the site you want to connect to, such as ensuring an SSL certificate is associated with the domain name and signed by a trusted authority, or verifying an SSH fingerprint out-of-band. Hidden services on Tor are not subject to this problem because their .onion names are self-authenticating as hashes of their public keys.
    95 
    96 '''How does tor relate to ipv6 and how should typical applications handle ipv6 if they use tor (or tor via Privoxy)?'''
    97 
    98 Like a dog talking to a quasar... I never was good with similes.
    99 
    100 Tor carries TCP data (does it? Maybe it just carries some data that is then transported over TCP... I know, for instance, that it also contains IP and port... TCP doesn't) over another layer - currently IPv4. There is work to make Tor work with IPV6, but I am not aware of it being completed.
    101 
    102 As for how an application would interface with it -- depends. It could use SOCKS; in that case, I think it would have to use SOCKS5 in the event of addressing IPv6 (rather than domains). This could be hacked around by adding a .ipv6 domain - nasty.
    103 
    104 Privoxy? Same as currently, if it handles it..
    105 
    106 '''What version of libevent should I be using?'''
    107 
    108 the latest.  at least 1.1
    109 
    110 '''How to use Tor in squid? For using Tor on a network using Squid as proxy, for example...'''
    111 
    112 '''How to use Tor with PF (Packet Filter, found in OpenBSD, NetBSD, DragonFlyBSD and FreeBSD)?'''
    113 
    114 
    115 
    116 '''How does Tor work with tabbed browsing, say with Firefox?  Do these requests all follow the same circuit through the Tor network? Can an eavesdropper link a user across all sites opened simultaneously in tabs?'''
    117 
    118 ver 1.5 Works fine for me, I use No-Script Plugin to help be even safer. Anyone else have a problem with Firefox. Weither the request follow the same curcuit is out of my realm. My surfing experience is good to just fine. ProBastion
    119 
    120 They will most likely all use the same circuit.  https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#ChangePaths
    121 
    122 '''When using the Tor/Privoxy configuration, is there an easy way to switch Privoxy between using Tor and using the standard connection (to allow for secure browsing, but also allowing a more direct connection when needed to keep large file transfers from bogging down in Tor)?'''
    123 
    124 It is possible to do this - however, it involves manually editing the config files for Privoxy, as well as possessing administrative/sudo access for your machine.  Also, once Privoxy is toggled to use a direct connection instead of Tor, your IP will be visible, and Privoxy does n ot provide as much security alone as it does with Tor.
    125 
    126 If you wish to do this, you will need to make a copy of your Privoxy config file, and comment out the line that causes Privoxy to use the Tor service.  Once you have done this, to switch over, just stop Privoxy, swap the config files, and restart it. You can also automate the process with a very simple shell script - an OSX version including sample config files and a shell script can be found [http://idlecircuits.com/privoxyswitcher.zip here], and the script can be used as an example for other *nix systems.
    127 
    128 -- In fact, there is no need to stop/restart privoxy. On my system, I have the privoxy config file owned by me, so I can edit it directly. Changing between tor and no-tor is as simple as editing one line.
    129 
    130 Here's the relevant lines from my privoxy config file:
    131 {{{
    132 # Tor:
    133 #
    134 ## forward-socks4a / localhost:9050 . 
    135 forward-socks4a .onion localhost:9050 .
    136 
    137 # Do not torrify these (high volume/speed concerns, as well as PhP BBS
    138 # systems that consider a changed IP to be a new login.):
    139 forward .blood-bowl.net .
    140 forward .qemu-forum.ipi.fi .
    141 }}}
    142 The line with "##" on it is the line to toggle. Remove those to enable tor, add them to disable tor.
    143 
    144 NB: Every PHP BBS site I've seen will consider you to have logged out and relogged in if your IP address -- as seen by the PHP site -- changes. This means that if tor ever switches circuits and changes exit node, those sites will reset your "unread messages". I have not been able to find a decent way to solve this with TrackHostExits, given that vidalia will overwrite my tor config occasionally (and has no support for adding these internally, so I have two editors trying to change the tor config), the length of time needed to track varies from 30 minutes at some (forced logout after thirty minutes of idle time) to 24 hours at others, dealing with the occasional dead exit node (and then you need to use a new exit node earlier), etc. And, my list of exception sites is currently 26 lines long.
    145 
    146 '''Tor works fine for POP3 email. But, Whistle-blowers and others who need anonymous
    147 political free speech must have reliable SSL smtp email services. How can Tor be used
    148 by them when *all* smtp ports, eg, ports 25, 465, 587, etc are now blocked by Tor exit
    149 servers? Blocking port 25 helps to defeat spammers, but the smtp SSL/TLS ports are not
    150 generally not used by them. Is there any solution with Tor to help the free speech folk
    151 and others who need to use secure, reliable smtp services? (votes: 6)'''
    152 
    153 
    154 '''How would one route his email through Tor? My email client (Microsoft Entourage for Mac OS X) has support for SOCKS and TUNNEL proxies, but setting my mail proxy for SOCKS 127.0.0.1 port 9050 or 8118 both produces errors when trying to proxy to SSL SMTP servers via port 25. What am I missing here? Also, setting this proxy doesn't seem to affect incoming POP3 SSL mail, but only affects outgoing mail, albeit without success. A little guidance on how to configure POP3 email clients to use Tor would be much appreciated!'''
    155 
    156 An attempt to answer the smtp email questions above: The Tor exit servers are likely blocking smtp port 25 in an attempt to stop spammers. Some Tor exit servers *sporadically* allow TLS/SSL smtp over ports 587, 995, etc., but at the present time there is no consistent, reliable policy or service.  (Also your remote email provider must support the use of alternate smtp ports such as those above.) You could use the remailer network but there can be reliability problems with them. Of greater importance is the fact that the remailer network does NOT accept large messages, e.g., scanned documents which can easily be many MB each. If you are a whistleblower or other person who needs to send large documents quickly and anonymously, you have a real problem. At this moment, Tor is not the answer.
    157 
    158 
    159 '''Can Tor be used in a network that has NO DEFAULT ROUTE?  The only access method from this network is to use a traditional proxy.  Is there a way to chain proxies so that TOR requests are sent outbound via the standard proxy? (votes: 1)'''
    160 
    161 Maybe. If you can get some routes for the Tor servers, then that of course is great.... assuming it must go through the proxy, however, it will need to support sending Tor requests.
    162 
    163 Assuming it does.. AFAIK, Tor doesn't have built-in support directly for this. So, you'll have to make it look to Tor like it really can connect .. err.. normally.
    164 
    165 I can see several ways of doing this.
    166 
    167 You could overload the network commands and have them actually connect to the proxy.. that's easy but a hack.
    168 
    169 You could try doing something with OpenVPN; personally, I don't have any experience with it... but I'm guessing you could do something neat with it (I remember someone setting up an OpenVPN with Tor being used to route things.. so it supports socks, I think, in some way. In that case, assuming the proxy is socks... all done :) Oterwise, you could write an interface to make it socks).
    170 
    171 
    172 '''Can I help? (votes: 2)'''
    173 
    174 https://www.torproject.org/volunteer.html
    175 
    176 '''I've got a bug, now what? (votes: 2)'''
    177 
    178 The following is a quick summary of the information already in the [:../TorFAQ#ReportBug: FAQ entry].
    179 
    180 1) Make sure that it is an actual bug with Tor, and not with Privoxy, Vidalia, your OS, etc.
    181 
    182 2) Check to see if it's an unreported bug (at the [https://bugs.torproject.org/flyspray/index.php?tasks=all&project=4 bug tracker]).
    183 
    184 2a) If it's already reported, then see if you can add anymore information (in the comments of that bug) that will help the developers duplicate it and/or track it down. (This step requires you to login to your account at flyspray, or to create a new account.)
    185 
    186 2b) If it's not already reported, then start a new report with as much relevant information as possible. Relevant information includes tor version number, OS used, any relevant lines from the log, and what you were trying to do that caused the bug. (This step requires you to login to your account at flyspray, or to create a new account.) You may want to read [http://www.chiark.greenend.org.uk/~sgtatham/bugs.html How to Report Bugs Effectively].
    187 
    188 '''How does Tor relate to the Freedom Project? (votes: 1)'''
    189 
    190 This question is answered in this [:../TorFAQ#ComparisonFreedom: FAQ entry].
    191 
    192 '''Is there any way to forward an ident response via TOR so that the ident doesn't come back as whatever the end server wants, but your normal response? (votes: 1)'''
    193 
    194 no.
    195 
    196 '''How can I uninstall tor? (votes: 1)'''
    197 
    198 
    199 
    200 
    201 '''I have legal questions about running Tor. Is there anybody I can contact? ( votes: 1)'''
    202 
    203 Added 2.1.06- The Developers do not provide Legal advice. period! Over at the Tor Legal FAQ there is a written section by EFF lawyers. It aims to give you an overview of some of the legal issues that arise from the Tor project. Read the Disclaimer. The FAQ does provide a dialougue on the legalality & posssible scenarios of operating a Tor Server. They also provide you with contact information to a EFF Lawyer. The Tor FAQ also provides a links to an Abuse FAQ, & Tor Technical FAQ Wiki.  See this address for more information along these lines. https://www.torproject.org/documentation#Support
    204 
    205 
    206 '''If I set up Tor to only act as a router node (reject *:* in torrc) can I still be a contact point for hidden services?'''
    207 
    208 yes.
    209 
    210 '''Can anonymity be broken if all Tor servers in the chain are compromised/malicious and so are keeping logs to trace the chain?'''
    211 
    212 Yes. Indeed, if all the servers in a circuit are compromised then they need not even be communicated with.. the entry node can decipher for all the (possibly even non-existent) nodes. In order to maintain a superficial view of anonymity, it would probably be good to forward it to the exit server however.
    213 
    214 '''What system resources does a Tor server use?  The FAQ already discusses memory a bit.  What about CPU?  Encryption is CPU-intensive.  Specific question I'd like answered: I'll be setting up a TOR node bandwidth-limited to about 256kbps (half my upstream bandwidth).  Will an old 300MHz G3 Mac easily handle this, or will a faster processor be needed? How 'bout a P90?  Presumably, TOR's disk usage and I/O is minimal.''' (Votes: 1)
    215 
    216 On older machines, probably reliability (antiques belong in museums) and memory are bigger concerns than processor speed.  You'll want to avoid swap (Tor's disk usage is rather low, but not if you're swapping...), so make sure your memory's adequate (my server runs with a load about half what you mention and, according to ps, is claiming 65MB of RAM).  Based on system loads from newer machines, simple multiplication, and a large margin of error, if you're running an otherwise light load under Linux or BSD, the 300MHz machine should work just fine.
    217 
    218 == Cannot resolve Foo.onion/Resolve requests to hidden services not allowed ==
    219 
    220 tor-resolve doesn't seem to work, i get this:
    221 {{{connection_ap_handshake_process_socks():  Resolve requests to hidden services not allowed. Failing.}}}
    222 from the copy of tor running locally. Please help!
    223 
    224 (from original questioner: thank you.  I got the mistaken idea that this would work because it is suggested in the 'how to torrify an application' article on this wiki.  It makes more sense now.  Someone who understands better might want to update that document)
    225 
    226 This question is answered; see [:../TorFAQ#AccessHiddenService: How Do I Access Tor Hidden Servers.]  You get this message when you try to use tor-resolve to resolve the address of a hidden service.  But hidden services are ''hidden'' - they don't *have* an IP address you can use.  Instead, you need to pass the hostnames to Tor directly.
    227 
    228 == Clock Skew ==
    229 My system clock is behind 3 days and I don't have permission to change it.
    230 Therefore all the certificates are invalid.
    231 Is there a runtime option to skew the time?
    232 
    233 This should not a problem as of 0.0.9pre6.
    234 
    235 == Does not connect to port xyz ==
    236 All of a sudden, Tor will no longer let me connect to my distant smtp server.
    237 The smtp port used is 587 and the connection is SSL. Why is this now happening?
    238 
    239 587 isn't in the default exit policy. The tor node known as bollox had an
    240 accept everything policy so your port 587 requests would have always gone through that.
    241 As bollox is no longer around there are no exit nodes that allow port 587. If you
    242 control this smtp server, try changing it's port number to something over 1024.
    243 
    244 == Debian and how to use the package management system ==
    245 
    246 Also would recomend posting default config files for debian online since apt will not reinstall them if they are removed (/etc/init.d/tor and /etc/torrc for example)
    247 
    248 '''Answer''': RTFM.  dpkg differentiatea between two states of package removal.
    249 There's ''remove'', which will just remove the normal files a package comes with,
    250 and there's ''purge'', which will remove configuration files also.  Changes to your
    251 configuration (like you removing them) are kept over a remove/install cycle.  If
    252 you want them to installed anyway, you should install with
    253 {{dpkg --force-confmiss --install tor...deb}}
    254 or just purge tor (which will delete /var/lib/tor with its keys if you are a server!), and then install it again.
    255 
    256 == . ==
    257 After uninstalling everything then reinstalling on debian (using apt-get of course) nothing loads in a browser or anything, eventually a 503 will come up.  Tor is running and privoxy is running, both correctly configured(I think).  If this is a configuration problem, where can I find more information about configuration in debian?
    258 
    259 '''Answer''': Duh.  Have you checked out {{{/etc/tor}}}?  What about {{{/var/log/tor}}} and {{{/usr/share/doc/tor}}}?  Why do you think it would be any different than on other OSs?
    260 
    261 == Privoxy config ==
    262 
    263 Similar to above, on brand new install of sarge with tor and privoxy browser, gaim, etc will spend a long time trying to connect eventually failing with 503, if tor is not running a 503 is instant.
    264 
    265 '''Answer''': Privoxy by default does not allow CONNECT to ports other than 443.  Fix your privoxy config.
    266 
    267 {{{weasel@galaxy:/etc/privoxy$ grep limit.con default.action | grep -v '^#'
    268 +limit-connect{1-} \
    269 }}}
    270 
    271 (If someone writes a proper question, this might actually go into the FAQ)
    272 
    273 == How To Configure One's Web Browser So Tor Is Only Used For Some Sites But Not Others ==
    274 '''Question''': Can I configure Tor so it will only use the onion routing network for some sites but not others?
    275 
    276 '''Answer''': No, Tor itself is all or nothing, a request either goes through it or it does not.
    277 
    278 For privoxy, however, you can use forward lines to make some hosts use tor, some use the normal system, and others use whatever other proxy you want.
    279 {{{
    280 forward-socks4a / localhost:9050 .
    281 forward-socks4a .onion localhost:9050 .
    282 
    283 # Do not torrify these (high volume/speed concerns, as well as PhP BBS
    284 # systems that consider a changed IP to be a new login.):
    285 forward .blood-bowl.net .
    286 forward .youtube.com .
    287 forward .qemu-forum.ipi.fi .
    288 forward .vidalia-project.net .
    289 }}}
    290 
    291 Here is an example. This uses privoxy for all sites (ad filtering, etc), and then specifies that some sites go through tor, and some do not.
    292 
    293 Privoxy uses the LAST match. So, the first line says "Use Tor by default". It can be turned off. The second line says "Always use Tor for .onion". After that are lines for "Never use Tor for these".
    294 
    295 Older, wrong information:
    296 Privoxy is also all or nothing in the sense that if a request has made it to Privoxy then either Privoxy is set up to go through Tor or it's not, there does not appear to be a way to program Privoxy so it will use Tor for some requests but not others.
    297 
    298 There is a script for OS X, available [http://idlecircuits.com/privoxyswitcher.zip here], that will make it such that Privoxy never uses Tor but this is an 'all or nothing' mechanism. The script will either start Privoxy such that all requests go through Tor or no requests go through Tor.
    299 
    300 There is one mechanism that is at least useful for web browsers, it's called a pac file. It was invented by Netscape, the original documentation is available [http://wp.netscape.com/eng/mozilla/2.0/relnotes/demo/proxy-live.html here], but it is now supported by all major browsers. One can use a pac file to program the browser to use the Privoxy proxy for certain requests but not others. For example, the following pac file will cause all requests to Google or to the special Privoxy configuration addresses to be sent to Privoxy (and hence Tor) but will allow other other requests to go out without Privoxy/Tor being used:
    301 
    302 {{{
    303 function FindProxyForURL(url, host) {
    304         if (shExpMatch(host,"*google.*") ||
    305             shExpMatch(host,"config.privoxy.org") ||
    306             shExpMatch(host,"p.p"))
    307                 return "PROXY 127.0.0.1:8118";
    308         return "DIRECT";
    309 }
    310 }}}
    311 
    312 To configure Firefox to use a pac file under OS X go to Firefox->preferences->General->Connection Settings...->Automatic proxy configuration URL:. Enter in a URL (you can use file:// to point to a local file) that points to your pac file and click reload.
    313 
    314 It's probably not a good idea to use pac files with Safari on OS X as its pac file support seems to be more than a little buggy.
    315 
    316 The pac file solution is far from ideal. It won't apply to non-web access and it runs into problems such as the bad pac file support in Safari. It also is not secure. A malicious website can trivially bypass this mechanism by placing pictures on its website from domains that it controls but are unlikely to be on a 'black list'. Therefore this mechanism is only useful with Websites that are not in and of themselves malicious but rather, due to their nature, can collect substantial amounts of personal information that one would rather not release. A search engine is a classic example. If and when privacy is a critical concern then the only proper course of action is to get rid of the pac file and instead configure all connections to go through privoxy/tor.
    317 
    318 
    319 
    320 '''I've been banned as an contributor at Slashdot! I run a Win 2003 server, with a decent pipe. They said that if I blocked them they would let me contribute again. I did an edit on my torrc file by adding a line:
    321 
    322 reject *:66.35.250.150 (which is Slashdot.com by using an online DNS 'dig' page
    323 
    324 I add the above right after my default exit. Which was just this:
    325 #ExitPolicy accept *:6660-6667,reject *:* # allow irc ports but no more
    326 ExitPolicy accept *:119 # accept nntp as well as default exit policy
    327 #ExitPolicy reject *:* # middleman only -- no exits allowed
    328 reject *:66.35.250.15
    329 
    330 Is this the way to do this, and just block Slashdot? Any help would be helpful, I've googled, did the torproject.org site, etc. But I'm not real UNIX centric (though thats changing) so just wanted to run it by some community persons. '''
    331 
    332 
    333 Well, you don't appear to allow exits on HTTP ports so I don't know why they blocked you. Fascists? [Ed. Fascists put their belief into the state... I doubt Slashdot does. Really, it's authoritarian]
    334 
    335 Anyway, you should probably block their IP rather than ports that happen to be theirs ;) (which don't exist - surprised tor let you do that..)
    336 
    337 To clarify, the syntax is ''ip-address'':''port'', so reject *:66.35.250.15 is blocking all requests to exit port number 66.35.250.15 at all ip addresses. This obviously doesn't make sense. What you want to do is reject 66.35.250.15:* to block all slashdot traffic.
    338 
    339 Also, the fourth line of this page reads: ''this is '''not the place''' for random it doesn't work or how do I do foo questions.''
    340 
    341 '''What is the significance of the changes in the Bittorrent Torify HOWTO?'''
    342 
    343 I noticed I can't connect with btdownloadcurses through proxychains any more. Looking for answers, I went back to the Torify HOWTO and noticed that it had been altered. Where it used to explain about using proxychains to run bittorrent through TOR, which I used successfully for over a year, it now says that Bittorrent "uses a mechanism similar to TOR." That was certainly news to me. How is the generic Bittorrent client technically similar to TOR in any way? I have always heard that the generic Bittorrent client offers almost no anonymity at all. Now I'm reading that Bittorrent and TOR are practically the same thing and it would be redundant to use them together. Seems a bit curious.
    344 
    345 As a sub-question, let me just ask directly: Is it true that Bittorrent through TOR via proxychains no longer works?
    346 
    347 Also, the same page now mentions a technique of using Tor to connect to the tracker only, as opposed to the peers, by including the line --tracker-proxy 127.0.0.1:8118: on the command line. However, I see no documentation of this option in the btdownloadcurses client and I find it a bit suspicious that the format of this option uses a hyphen rather than an underscore as all the other command line options that are listed as being compatible with btdownloadcurses use underscores to separate options with two words such as --check_hashes <arg> or --report_hash_failures <arg>. Is that a typo or an undocumented option that just happens to deviate from the naming convention of all the other options?
    348 
    349 '''How do you start and stop Tor and Privoxy in OS X (Panther) if you did not install the startup script? (needs to be added to installation instructions)'''
    350 
    351 
    352 On my system, the privoxy startup file ultimately runs
    353 {{{sudo $INSTALLDIR/privoxy --pidfile $pidfile }}}
    354 
    355 with INSTALLDIR being where you installed it, and pidfile being a filename that will hold the process ID.
    356 
    357 Tor can be started as a normal user -- just run the tor program. On my system, it runs as
    358 {{{/usr/bin/tor ControlPort 9051}}}
    359 
    360 Note that Vidalia is responsible for starting tor, normally.
    361 
    362 '''How do you configure the proxy if you are using Tor and Privoxy in OS X (Panther) with a router's firewall and the built-in OS X firewall, e.g. when using Wi-fi to connect to wireless router?  (needs to be added to installation instructions)'''
    363 
    364 I'm not sure that this is OS X specific. For any firewall, you need to add two incoming ports, 9001 and 9030 by default, to the list of approved ports.
    365 
    366 For Mac OS X, go to control panel, sharing, firewall, and then click "new" twice. The first one is port 9001, label "Tor Server", the second is port 9030, label "Tor Directory Mirror". Both of these are TCP ports, and the "port name" field should be "other".
    367 
    368 If you have BOTH the Os X firewall, and the router firewall, then you also need to open those ports on the router. Details are router specific.
    369 
    370 '''What to do (troubleshooting) if browsing slows to a crawl with Tor and Privoxy running in OS X?'''
    371 
    372 Somebody proposed the following solution, which ''should not be used'' as it will break Tor for everyone else.
    373 
    374 {{{CircuitBuildTimeout 6
    375 NewCircuitPeriod 3
    376 ExcludeNodes charlesbabbage,tutzing,TFTor,freetux4ever
    377 LongLivedPorts 80,23,21,22,706,1863,5050,5190,5222,5223,6667,8300,8888}}}
    378 
    379 CircuitBuildTimeout causes the client to drop an uncompleted circuit after 6 seconds; it will cause your tor to build circuits more aggressively than other nodes.  The default value is 60.
    380 
    381 Finally, port 80 is added to the "long lived ports" list. This will overload long lived ports, making tor unusable for people who need to use ssh over tor.
    382 
    383 
    384 '''I am running a Tor server on one computer on a network. Can I stop the other PCs on the same network from being k-lined on QuakeNet?'''
    385 
    386 
    387 '''Would it make sense to support binding to multiple ports in Tor server (e.g. to bind to ports 443, 22, 5190 etc.) for clients behind _really_ restrictive firewalls? If this was implemented one day, maybe you could also support binding to multiple specific IP addresses on multihomed servers?'''
    388 
    389 The changelog indicates that this has been possible since "version 0.0.7pre1 - 2004-06-02":
    390 ''Allow multiple instances of each BindAddress config option, so you can bind to multiple interfaces if you want.''
    391 
    392 The [https://www.torproject.org/tor-manual.html.en manual] says this about the ''ORListenAddress'' configuration option:
    393 ''... This directive can be specified multiple times to bind to multiple addresses/ports.''
    394 
    395 It also says this about the ''DIRListenAddress'' configuration option:
    396 ''... This directive can be specified multiple times to bind to multiple addresses/ports.''
    397 
    398 ----
    399 CategoryHomepage
     25My system clock is behind 3 days and I don't have permission to change it.  Therefore all the certificates are invalid.  Is there a runtime option to skew the time? (votes: 1)