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Ask Slashdot: How To Diagnose Traffic Throttling and Work Around It?
Aguazul2 writes "I live in Peru and use OpenVPN to connect to my own Linux VPS in the UK for non-live TV. Recently the VPN connection has slowed to a crawl (5% previous rate). Further investigation shows that all connections to my VPS from Peru (even HTTP) are equally slow, whilst the rest of the 'net seems fine. My VPS host says they do no traffic shaping, and connections from Germany to the VPS are fast. This leaves the NSA and Telefonica (Movistar) as suspects. Could the NSA be slowing all VPNs to/from South America because of Snowden and Greenwald? A traceroute shows traffic going through domains with NYC in their name — are my packets being indefinitely detained in transit? Or maybe it is Telefonica and their Sandvine traffic management? Either way this certainly isn't network neutrality, especially on an 'unlimited' plan. Is there a way to tell for certain who is throttling me? If Telefonica have throttled traffic to/from that one IP address, what options do I have to work around it? It seems that separate connections are throttled independently, so can I multiplex over many UDP ports without having to hack OpenVPN myself? This is really frustrating, especially with two untrustworthy parties on the route. I wonder, is this kind of mess the future of the internet?"
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I've had a client I provide consulting for suggest that their poor connectivity is also in some way due to the NSA. People need to understand that it is paramount to the NSA that they are covert. They do not need to do real-time processing of the data: that is only necessary for filtering. It suffices for them to simply capture raw data for later analysis or decryption as necessary. Of course capturing data does not result in any slowdown or other noticeable effects. It does not make any sense whatsoever for the NSA to be slowing or otherwise blocking connectivity, as that is counterproductive to the acquisition of intelligence data.
It's just amusing to me to see NSA as the scapegoat of the day for any quirk anyone experiences related to computers or connectivity in general.
Better known as 318230.
You are seriously lacking basic data telecommunications experience. All government tapping is span port based. This means that it is passive, not active, so there is no latency involved.
Years ago I worked on a broadband remote access server and one requirement we got was to support lawful traffic interception. Basically all law enforcement wanted was a copy of all of the packets. Packets are not slowed down or stopped by this process.
In my case the hardware was just not capable of doing what was needed but there was plenty of off the shelf hardware that could be installed in the network to provide the filtering and packet mirroring needed.
It is possible that one of the VPN's upstream providers is running into congestion. One of the best ways I have found is to use traceroute. At one time I was getting unusable Internet connectivity through AT&T after they acquired my local cable modem network from @Home. It took them many months to discover that throttling all aggregate upstream traffic to 128Kbps is a bad idea. As much as people bitch and moan about Comcast, it is lightyears better than anything I got through AT&T. In this case, traceroute clearly showed where packets were getting delayed and dropped, which was one of the routers inside AT&T.
Unfortunately, for a VPN this is much more difficult since the Internet hops are hidden via the tunnel.
There are many different ways to tunnel traffic. If the tunnel is Microsoft's PPTP protocol then it's not very secure. If on the other hand it is using IPSec then it should be a lot more secure. There are also other tunneling protocols that do not specify any encryption, i.e. MPLS.
This post is encrypted twice with ROT-13. Documenting or attempting to crack this encryption is illegal.
My office Internet connection recently went from about 30Mbps down to 1.5Mbps, then back to 50Mbps a month later. No explanation, and speed tests to our ISP all came through at full speeds. We only saw problems on routes going outside our city and headed west. There were also a few inaccessible sites, but those were in very specific local areas. Ultimately, the best guess anyone could come up with is that a network to the west of our city had some routing problems.
We weren't the only customers to complain about a slowdown, but our ISP couldn't really do much about it. The Internet is made up of many networks working together, and sometimes shit happens. I wouldn't jump so quickly to assume it's non-neutral throttling or the NSA, when it could just be a careless guy with a badly-aimed backhoe. Give it some time, see if it improves, and if not, it may be time to move your VPS.
As an aside, you're likely going through New York because that's how you're reaching Europe to get to your UK-based VPS. Many transatlantic cables end in New York City, mostly because the stock market pays dearly for the few nanoseconds of lower latency.
You do not have a moral or legal right to do absolutely anything you want.
If you are a US ISP, it is required that you have monitoring in place. If you don't want to hamper your entire infrastructure while doing so, you get a bunch of taps and install them all over your network. One very good provider for this is Gigamon. Taps do not add any latency in your traffic. They are completely invisible to all other network devices. Traffic shaping (throttling) is done by the source typically but can be done at the destination ISP. Basically, your connection is assigned a Package in the Shaper. The packages determine how fast each classification groups of traffic are allowed to go. Classifications are determined by whoever manages the shaper for that ISP. Shapers can also dynamically change the speed you are allowed to have for a classification group based on bandwidth used, time used, and volume of traffic.
If you are not throttled from Germany to your home but are from Peru to your home, chances are you are throttled from your ISP in Peru. It is typical for transits to cross borders, so your traffic going through NYC is normal. BGP (the routing protocol of the internet) determined that to be the best path. This is mostly managed, but is still fairly dynamically determined by the routing protocol.
Course of action: Switch ISPs, get a new IP address (if they are not very good at configuring a shaper this will work, otherwise not), try a proxy, stop using it for a day or more and it will go away (temporarily most likely). This is done dynamically in the shaper. There is not some dude with his finger on a 'throttle' button. Everything is automatic. Just figure out the how their throttling deterministic state diagram works and you can avoid throttling. Most likely they are throttling you because of your volume of use. It costs a lot for transit access and you are using more than most others by streaming through a vpn.
I work in the ISP industry, and here's my $0.02...
The NSA (or other spies), not likely. Everything I have ever seen about what they do is passive monitoring. What that means is that somewhere there is a pretty dumb device (like an optical splitter) that takes one signal and makes two copies, one goes to the NSA, one on to its destination. In this arrangement there is no way for the NSA to inject data at all, including slowing it down. I am highly skeptical any government spying is the direct cause. It may be indirect, I'll come back to that in a minute.
Rate shaping is entirely possible, and would be most likely in your immediate provider. It's entirely common for residential consumer ISP's to employ products like Sandvine, or even more crude QOS controls to rate limit particular types of traffic (e.g. VPN or VOIP). Most won't admit to what they are doing as well.
Rate shaping is less likely, but possible at the country level. This is seen mostly in countries with strong government controls on technology (think Iran, China, North Korea). Egypt was doing it at one point in time. I'm not an expert on Peru, but I would not expect this problem in Peru.
Lastly, is plain old congestion. Likely your ISP has multiple paths to reach Europe, riding undersea cables. These are the most expensive assets an ISP owns, and often get congested before they get upgraded. It's entirely possible for instance there is one cable they use from South American to Western Europe that is congested, while another goes from South America to the US and is fine. You can probably map these routes out by traceroute, and may find that particular routes always show poor performance. This also happens, but to a lesser degree, where two ISP's meet. There can be peering disputes, or one customer may not order enough capacity from their vendor. Either way the result is full ports that degrade service for everyone passing through them.
Now, here's where the spies come back in. If a particular spy agency decrees "all new connections must have our spy apparatus on them" they can in fact be the delay to a new connection getting set up. It's not that they are delaying any packet traffic once it is up, but rather they are delaying the installation by not having their equipment ready on time for a new connection. I don't think this happens often, but I'm sure it does happen in some places.
So sadly, this is probably some plain old incompetence/bad luck. Someone either could not afford a timely upgrade, or didn't correctly order an upgrade early enough to get it installed before there was a problem, and there's now congestion somewhere. If it's not bad luck it's probably your provider deciding your particular type of traffic is "bad", and should be rate limited down.
Some more info would be appreciated. So, here's the basics of a few things you can do to make sure it really is the network*. First use iperf on the client and server. Test it on both the tunnel interface and the WAN interface. Second, use top via a separate ssh session. Make sure OpenVPN isn't eating all your CPU or memory. Lastly, what provider are you using? Lately the default Debian build that Edis.at gave me needs an ifconfig up/down every other day.
I've had a similar problem when using my own VPS as an HTTP proxy via OpenVPN. It turned out, the proxy application was crap. Allowing the machine to route packets and using it as a default gateway for all traffic fixed the problem, or at least worked around it.
Now. If it really is blocking, there are a couple of ways around it. The more complicated ones involve using some other VPN application. When dealing with more than one client, that rapidly becomes annoying. A simple one is using an SSH connection as a SOCKS proxy for your browser. It's not elegant, but it works. Another way is to mask your OpenVPN connection by encapsulating the UDP or TCP packets. Once again, SSH port forwarding works, but that's a TCP solution. socat was designed to do things like that, so it seems like a good choice. Finally, there's Ping Tunnel. It embeds traffic in ICMP packets.
Whoever is throttling you might detect one or more of these, but they're probably using some sort of signature based detection. Just about anything that requires a command line should get through.
Remember, since you are technically savvy enough to roll your own, you are the one percent. Good luck, and please let us know how it goes.
*I know you're probably familiar with all of these things. Just assume that I put this section here for those who aren't.
So lets pretend that we've just completed writing this code, as opposed to having just completed sabotaging it -Altera
Did you not watch the video from the Dot Com mansion raid? lol
Build it, Drive it, Improve it! Hybridz.org
No. That's the KGB. Since the alleged fall of the Soviet Union, they've had to run their operations under far more secrecy than ever before. Sometimes, this means they have to leave a job before they have a chance to clean up entirely.
In your case, you've become a test subject for the Soviet loyalists' conspiracy to sap and impurify all of our precious bodily fluids. They are attempting to steal your very essence, and it is your patriotic duty to resist them. Place loaded mousetraps around your bed to damage the stealth robots that are invading your sanctuary of slumber. To prevent their essence-extractor from invading your body, apply a liberal coating of cyanoacrylate to your penis before sleep. It may cause an unusual sensation, but that's far better than the empty fatigue the Communists will inflict.
The NSA is actually fully aware of this conspiracy, and you should assist their efforts to protect our precious bodily fluids. As it is clear that the Red Menace is most interested in corrupting your penis, you must aid the resistance research that is underway. As the NSA must also keep their research secret, no scientists will contact you directly, but you can still contribute to the noble cause by announcing publicly every time your penis functions normally, and especially whenever it does not. This is best accomplished by loudly shouting your results from an open second-story window, followed by displaying your penis for remote optical inspection. Be sure to announce that you are a subject of General Jack Ripper's studies.
The Soviet collapse was a sham, designed to lull the Americans into a false sense of security. The KGB have not given up, and neither can we. God willing, we will prevail, in peace and freedom from fear, and in true health, through the purity and essence of our natural fluids.
You do not have a moral or legal right to do absolutely anything you want.
Who gave a slashdot account to that computer trained to tell jokes?
That may have been their theory, or it may have been they wondered if US gov was intentionally slowing VPN connections from that part of the world.
If the theory was that capturing data would slow it down, the answer is "no". For that, you'd use port mirroring. Where a switch or router would normally take data in on one line and output it on another, you set it to accept data on the one line and output it on TWO others simultaneously. The data still flows at the same speed. It just flows to two locations separately - the intended recipient and the government.
Many ISP's perform what is known as ICMP rate limiting. Traceroute and Ping both use this ICMP protocol *i'm not going to get into semantics* where as you start traversing the internet past your internet service provider your pings and such to any point along the path have a high chance of being dropped due to this. The only way to see your actual latency is using a host-to-host ping. From your source destination to your final destination. Traceroute acts as sending a ping to each and every hop in between the source and final destination (assuming the TTL doesn't expire or somebody's carrier firewall just doesn't' start letting replies come back through, ie, multiple * * * responses but still able to reach your end destination), they are in no way obligated to reply properly and or in a timely fashion to your Ping request. During the early days of the internet we didn't have many of the problems that we have today and these tools worked flawlessly during this time and really could tell you where your latency is (these tools still function normally in a local lan if you are not doing any "crazy" firewalling tactics). This is no longer the case with ping an traceroute.
IN EXTREME CASES it may be possible to route around other carriers using private tunnels, It's not something your average joe will not likely be able to accomplish without multiple services across the country or paying for some sort of service to do so. AKA you are a business with $$$$. There are instances where it can be done, but are few and very far in between.
If your ISP only has 1 way out to reach specific destinations which are having problems. Provide them traceroutes showing them good responses AND bad responses from when and where you are seeing the problem. The only thing a carrier is going to care about is your "average" response time in milliseconds, not your "maximum" response time.
Didn't you know? Slashdot is a large Turing Test system. Most of the participants are AIs.
Interestingly, the most promising test results are with the "First Post" trolls. Apparently nobody can imagine that an AI could be that stupid.
The Tao of math: The numbers you can count are not the real numbers.
The OP mentions Sandvine: the EFF has a tool called Switzerland.
Is your ISP interfering with your BitTorrent connections? Cutting off your VOIP calls? Undermining the principles of network neutrality? In order to answer those questions, concerned Internet users need tools to test their Internet connections and gather evidence about ISP interference practices. After all, if it weren't for the testing efforts of Rob Topolski, the Associated Press, and EFF, Comcast would still be stone-walling about their now-infamous BitTorrent blocking efforts.
Developed by the Electronic Frontier Foundation, Switzerland is an open source software tool for testing the integrity of data communications over networks, ISPs and firewalls. It will spot IP packets which are forged or modified between clients, inform you, and give you copies of the modified packets.
Switzerland is designed to detect the modification or injection of packets of data traveling over IP networks, including those introduced by anti-P2P tools from Sandvine (widely believed to be used by Comcast to interfere with BitTorrent uploads) and AudibleMagic, advertising injection systems like FairEagle, censorship systems like the Great Firewall of China, and other systems that we don't know about yet.