- tor-relays - lists.torproject.org

Hibernation timing & bandwidth
by Steve Snyder 05 Oct '11

05 Oct '11

I have a relay with a fixed monthly bandwidth limit, so I expect the relay to hibernate toward the end of the month. (I'm trying to spread the bandwidth out over the month, but actual relay utilization cannot be estimated accurately.) I'm wondering how to time this hibernation period. What I'd like to avoid is hibernating during a period when relay hibernation is common. If I know that most Accounting-limited relays hibernate at, say, the end of the calendar month, then I can schedule my hibernation to be at the start of the calendar month. If most hibernation is done on Saturday (day 6, the end of the week) then I can arrange to sleep on Wednesday (day 3). Is there a known trend to relay hibernation that I can schedule against? Thanks.

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bad line
by cmeclax-sazri 05 Oct '11

05 Oct '11

You may have noticed a deterioration in my throughput over the past month. Yesterday I called my ISP, trying to figure out the problem, and was advised to put one computer directly on line and see what happens. I did this for an hour about 20:00 UTC, taking Tor and the mail server off line, and connecting just the laptop, on which I did pings. I saw 25% packet loss with no uploading or downloading (the laptop does have a Tor client, but I was not using it). Further testing with 2ping shows that the packets lost are incoming. Hopefully the problem will be resolved either early next week or the week after (I'll be out part of the week). cmeclax

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Response back from DataCell/Iceland
by Patrick Hooker 01 Oct '11

01 Oct '11

I wrote a nice letter to DataCell about the bandwidth my Tor router was using and got a quick and good response. It also sheds some light on Datacell's(in Iceland) connectivity to the outer world. " Bandwidth in Iceland is an issue in terms of most ISP's charge by the gigabyte transferred. This is the case because most ISP's depend on Vodafone or Siminn for their backhaul and those charge by the transferred Gigabyte on the international side while they don't charge for national transfer. They do that because they pay outrageous prices on the link to central europe and probably because they want to make a lot of money too ;-). Our connectivity does not depend on them however. We managed to get a somehow acceptable price for international connectivity. Its still 5 times higher than bandwith in central europe but its at least not 50 times as high as the first offers we got. At the moment we have excess capacity. Our links are loaded like less than 1%. Once we get more customer, the link will be filled up. Our infrastructure is configured to use fair queuing. This means that every IP in our network gets a fair share of the bandwidth which is the way we operate. I don't mind having traffic on the excess bandwidth as long as all customers get their guaranteed part. If it would become an issue we would enforce it by using rate limits." So, for now anyway, there doesn't seem to be a problem with my running nearly 100GB/day through my Tor middle router. The TOS excludes the running of open mail proxies doing anything illegal (by Iceland's laws), this to be expected. I can see nothing in the TOS would directly rule out Tor, at least a non-exit router. All my contact with DataCell has been very friendly, I'd recommend them to anyone who can afford ~US$70/mo. for a virtual server. Just remember that when in Iceland, never carelessly throw stones and be polite to the littl' people. Bless Bless, Patrick

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Updating arm
by Bill White 30 Sep '11

30 Sep '11

Hello all -- I'm running a brand-new relay (Diogenes) and at the same time I've discovered arm, which I find an excellent way to learn the art of running a Tor relay. I'm also a Linux beginner, so please forgive my ignorance about my question. My relay is now running arm v. 1.4.0.2, and I want to upgrade to the latest version, 1.4.4. I have downloaded and extracted the tarball (http://www.atagar.com/arm/download.php) However, running ./configure, and every combination of "how to" install/upgrade I can find, results in failure. And "sudo apt-get install tor-arm" tells me I already have the most recent version posted in the repository, which is where I obtained my original arm install. Can someone help me upgrade arm to the latest version? I'm running Ubuntu server 2.6.38-8-server x86_64 Thanks in advance, -- Bill

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Introduction
by Patrick Hooker 29 Sep '11

29 Sep '11

Greetings, Thought I'd say a quick hello since I'm following the list for several days now. I'm running a non-exit relay, "Anonimulo" on a VPS account I have in Iceland. I'm not sure how long I'll be able to keep it up, I may need the bandwidth/CPU time for other activities in the future. For now I'm giving 1MB/s to Tor. I had been wondering just how to monitor my relay when I read about ARM on this list. I installed ARM, fiddled with the torrc a bit and was pleasantly surprised with ARM's display. Kudos to the developer! It appears that Anonimulo is running flat out at max bandwidth too. Yay! Patrick

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Re: [tor-relays] max / burst speed
by Rick Huebner 29 Sep '11

29 Sep '11

On 9/27/2011 1:37 PM, "Steve Snyder" <swsnyder(a)snydernet.net> wrote: > Either there is simply not enough traffic to saturate all available middle nodes or Tor's node selection algorithm is, um, sub-optimal. I just started my relay a month ago, so I've done some research, and it seems to be pretty complicated. Please excuse what turned into an over-long post, but I think this is info that new relay operators don't generally know, and should. At its base, the traffic allocation scheme is elegantly simple: each client randomly selects circuit participants based on the sum of all the relays' bandwidth values from the most recent consensus (not counting complications like starting with a guard node, ending with an exit, etc.). So ideally, a relay with twice the bandwidth of another will (on average) be selected for circuits twice as often, and (again, on average) end up processing twice as much traffic. And also, if the total bandwidth demand from all clients is enough to consume, say, 60% of all Tor relays' available bandwidth, each relay will (on average) be kept operating at about 60% of capacity. But... the bandwidth figure in the consensus that clients use to select relays is not a simple figure. Apparently, it used to be based on the rates reported by each relay in their uploaded server descriptors, but people tried to game the system and fed it bogus data, so that was replaced by the authoritative servers going out and measuring the actual bandwidth of each relay by downloading a test file through it to see how fast it really went. So the values your relay uploads in the descriptor are ignored now, and your set Rate and Burst speeds aren't relevant for traffic allocation except in as much as they affect the speed that the official bandwidth scanner can download the test file through you. The only bandwidth figure that matters for driving traffic to your relay is the one reported in the consensus, which you can see at https://metrics.torproject.org/networkstatus.html, or from your own relay's DirPort at http://<relay>:<dirport>/tor/status-vote/current/consensus if you're a directory mirror. Note that these are not the values from any of the TorStatus servers, they're displaying something else entirely (and not always the same thing as each other, either). So anyway, don't expect a change in your torrc file to immediately bring you more traffic. Your relay has to get rescanned first, which probably only happens once a day. OK, fair enough. But those bandwidth numbers aren't just the simple speed which was seen when the scanner last downloaded a test file through your relay. To smooth out random speed changes as your relay is remeasured day to day, the bandwidth scanners use some kind of fairly slow exponential moving average of your download speeds. So it takes considerable time for changes in your relay's speed to slowly seep into the bandwidth number in the consensus. And for new relays, it seems that the initial value which the new measurements are slowly averaged into starts out pretty low, so that your reported bandwidth also starts out pretty low, and then gradually rises over time to somewhere around your actual Rate limit. And by slow, I mean weeks; my new relay has been running for a month, and over that time, I've seen the reported bandwidth slowly, with many fits and starts and temporary setbacks, go from about 20-30 to ~200 (about half my actual Rate limit), and it's still rising. Which kind of has the effect of putting new relays on probation, and slowly feeding them more and more traffic over time to see how they do, which is not a bad thing at all. But new relay operators are usually excited and anxious to see stuff happen, and need to be aware of this slow starting ramp up period and not get too discouraged or give up because they're not seeing much traffic at first. OK, so the bandwidth rating that matters is measured and slowly averaged... but there's yet another layer. To improve the overall performance of the Tor network, and to help clients generally create faster circuits, there's another bias factor thrown in. I don't know the details, but faster relays have their measured bandwidth figures artificially boosted to drive even more traffic through them than their high bandwidth would naturally attract, and/or slower relays have their bandwidth figures artificially lowered to drive less traffic through them (not sure which or both, but the effect is the same regardless). So if the overall client bandwidth demand is, again, 60% of the total Tor network bandwidth available, instead of each relay being at ~60% capacity, the fastest relays will be more fully utilized, and, unavoidably, that means that the slower relays will be correspondingly less utilized. This might dismay slower relay operators who feel that they're being prevented from contributing as much as they'd like, but objectively, it's generally better for a Tor client to have a 300 KB/s circuit hop than a 30 KB/s one. The faster relays are just nicer for clients to use, and it's better overall for the Tor network to make sure they get used as much as possible. And if those fast relays are getting more than their prorated "fair" share of usage based on their actual speeds, that unavoidably means that slower relays are getting less usage than their speed would normally merit. But that doesn't mean the slower relays are useless! Simply by existing, those extra relays greatly increase the difficulty of various attacks on Tor, just because they *might* have been used for any given circuit. Also, the whole guard node system for making certain nasty attacks infeasible relies on having lots of potential guard nodes to choose between, even relatively slow ones. And of course, all exit nodes are especially precious, almost regardless of speed. And finally, even if they're not used all that much while client demand on the Tor network is low to moderate, they provide an important spare reserve of bandwidth to make sure that some relay somewhere will always be ready to handle a new circuit even if the network becomes very busy and manages to max out the high speed "backbone" relays, or Tor is subjected to some kind of DOS attack. So anyway, for all the relay operators asking "why isn't my relay being used more?", there's your infodump. If it's a new relay, or you recently upgraded/raised your speed limits, keep an eye on the official bandwidth figure for your relay in the consensus, especially the nice graph displayed in the Router Detail page that you reach by clicking your router link on the https://metrics.torproject.org/networkstatus.html page. If that graph shows any upwards trend, the effects of your change are still slowly percolating into your official bandwidth figure, and more traffic will appear as it rises. If it's plateaued out, you're getting your share of the overall Tor traffic based on your relay's overall performance and the total client demand on the Tor network. For slow nodes who've limited their overall Rate to avoid hitting bandwidth caps, you might consider using AccountingMax to cap the usage to a safe level, and increase your speeds; you may find it more rewarding to relay significant traffic for 6 hours per day and then hibernate for 18 than to stay on "inactive reserve" status all the time. From the overall viewpoint of the network, is it better to have 1000 new relays at good speeds up 1/4 of the time (effectively adding 250 new fast relays), or to have them at slow speeds all of the time, not being used much? I'm not really sure, but I've noticed that the AccountingMax hibernation feature is hardly used at all from what I see on TorStatus, and I wonder why. OK, enough already, this turned out way longer than I was expecting. Hope it helps.

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(no subject)
by Tim Myers 28 Sep '11

28 Sep '11

Stop Sent via BlackBerry by AT&T

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Re: [tor-relays] max / burst speed
by Rick Huebner 28 Sep '11

28 Sep '11

On 9/27/2011 1:37 PM, "Steve Snyder" <swsnyder(a)snydernet.net> wrote: > Also, I have come to distrust TorStatus. Why? Because difference sites will have different numbers while supposedly monitoring the same network. One of my nodes is currently showing an Observed bandwidth of 10KB (yes, ten) at torstatus.blutmagie.de while the same node is showing an Observed 83KB at torstatus.all.de. Don't take the reported values as gospel. They seem to be measuring different things. As far as I can tell, blutmagie.de appears to be calculating the average bandwidth actually used overall per day, i.e. the average of the rates shown in the Recent Read/Write History graphs, which in turn appear to be faithful copies of the node's reported extra-info data. all.de reports the node's own observed bandwidth figure from its most recently uploaded server descriptor, and I have no idea what it's showing in its Read/Write History graphs, it's not the extra-info history data, and I can't relate it to anything. So blutmagie.de shows how much traffic the different routers are actually processing on average per second, and all.de shows the peak speed reached by each router in a short sprint (10 seconds?).

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Re: [tor-relays] max / burst speed
by Rick Huebner 28 Sep '11

28 Sep '11

On 9/27/2011 1:37 PM, tor-relays-request(a)lists.torproject.org wrote: > No idea what shaping algorithm Tor uses, nor any clue on recommended > burst ratios under said algorithm. Anyone???. I believe Tor uses a token bucket algorithm (https://secure.wikimedia.org/wikipedia/en/wiki/Token_bucket) for traffic shaping. Which works sort of like a fuel tank with a steady rate of fuel being replenished each second (RelayBandwidthRate) and a max capacity of RelayBandwidthBurst bytes. If the tank is full, up to RelayBandwidthBurst bytes can be consumed, but only RelayBandwidthRate bytes will be replenished each second. So there's a sort of reserve available of Burst - Rate bytes, and consumption > Rate bytes/second depletes the reserve, and consumption < Rate refills the reserve, up to the max capacity. In general I think the higher the Burst you can allow, the better; it helps fast clients with small requests to zip through your relay quickly without clamping them to your overall Rate limit, and doesn't cost you anything since your long-term average is still enforced (bursts over your limit are balanced with slack periods under your limit). But I'm not clear on what the highest effective value would be. I could even see a point to having the Burst higher than your physical connection's actual limit, e.g. setting it to 10 times your connection's actual limit would allow bursts to max out your connection for 10 seconds (occasionally, to be balanced again by slack periods under your rate). But really, I doubt that values more than 2 or 3 times your Rate limit will actually matter, since Tor traffic doesn't seem to often come in those kinds of isolated high-multiple bursts (probably the natural averaging effect of having many clients routing dozens/hundreds? of circuits though your relay at once). A simple pragmatic test might be to run the Vidalia bandwidth meter for a day or two, and if the peak rate isn't hitting your Burst, it's high enough not to matter. One interesting side effect of a high Burst might be its impact on the way your relay's bandwidth is measured by the official bandwidth scanners, though. If the bandwidth scanner's test download file is small enough (less than many second's worth of your overall Rate limit bandwidth), a high Burst might allow the test file to be downloaded much more quickly than with a low Burst, raising your official measured bandwidth rating (and drawing more traffic to your relay). Larger test download files would mitigate this, but increase the scanner's workload and time between each relay's re-scans. Just a thought, I don't know how much effect this actually has.

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max / burst speed
by Sebastian Urbach 27 Sep '11

27 Sep '11

Hi all, I doubled my max / burst speed values for my relay a few days ago. Unfortunately the new values are displayes in the statistic but not used at all. Does anyone have a suggestion for me how to get more work :-) ? Thanks and cheers -- Mit freundlichen Grüßen / Yours sincerely Sebastian Urbach -------------------------------------------------------- Religion is something left over from the infancy of our intelligence, it will fade away as we adopt reason and science as our guidelines. -------------------------------------------------------- Bertrand Arthur William Russell (1872-1970), British philosopher, logician, mathematician, historian, and social critic.

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