WEBVTT 00:00.860 --> 00:04.280 So welcome back to the Knowledge Portal Video series. 00:04.760 --> 00:10.310 Today we are going to look into a very interesting module called as Limit Underscore Con. 00:10.520 --> 00:14.330 So basically it means limit underscore connection. 00:14.810 --> 00:25.310 So this module is specifically useful for servers which are providing download related content. 00:25.310 --> 00:32.390 So if you have a server with a lot of files which people will be downloading, then limit underscore 00:32.390 --> 00:36.050 connection module will be a very useful tool for you. 00:36.830 --> 00:39.110 So let me give you an example. 00:39.980 --> 00:44.960 So let's say this is your server and you have Nginx in it. 00:46.550 --> 00:49.370 Now you have bandwidth of 100 Mbps. 00:54.150 --> 01:00.060 And approximately you expect there are ten users who wants to download a file. 01:00.510 --> 01:02.700 So you have a big file over here. 01:03.630 --> 01:09.510 Maybe a software or maybe a video documentary which around ten users wants to download it. 01:10.870 --> 01:17.920 Now, among the ten users, two of them have 50 Mbps connection. 01:20.520 --> 01:21.470 And rest. 01:21.480 --> 01:26.790 Eight of them has around, let's assume two Mbps connection. 01:29.320 --> 01:36.850 Now, the problem that will happen over here is the two users with 50 Mbps connection. 01:36.850 --> 01:43.570 When they try and download the file, they will be occupying the full 100 Mbps bandwidth of the server. 01:44.110 --> 01:50.470 So rest eight people when they try to download the file. 01:50.650 --> 01:55.600 Either the download will be slow or the server will return 503. 01:56.950 --> 02:06.010 So during these type of scenarios, it is very important to limit the amount of connection speed that 02:06.010 --> 02:08.770 you give to each individual user. 02:08.980 --> 02:15.460 So during this instance of time, let's say you give ten Mbps to each user. 02:17.040 --> 02:21.030 Then essentially all the ten users will be able to download the file. 02:22.110 --> 02:28.830 But if you do not have any restriction on the amount of download speed a user can have, then typically 02:28.830 --> 02:33.540 the people who will have very fast download speed will choke up the whole server. 02:35.310 --> 02:38.640 So let's see on how exactly it works. 02:42.870 --> 02:47.120 So this is one of the CentOS directory. 02:47.130 --> 02:49.770 Well, I'll download a sample CentOS file. 02:49.780 --> 02:52.530 We'll download this 600 MB file. 02:54.300 --> 02:59.880 So I've copied the link and let's try and download it. 03:00.480 --> 03:01.860 So I'll go to temp. 03:05.620 --> 03:06.730 I'll paste it over here. 03:09.070 --> 03:12.460 So before we download that, let's actually test our speed. 03:13.120 --> 03:21.910 So I have this 100 MB test file which basically will help us know the true speed of the server. 03:22.150 --> 03:24.220 So I'll do w get. 03:25.780 --> 03:29.860 And let's see, what is the speed that our server is downloading the file. 03:32.920 --> 03:33.370 Okay. 03:33.370 --> 03:40.040 So the 100 MB file got downloaded and the average speed was around 17.7 Mbps. 03:40.060 --> 03:43.210 So you can consider 18 Mbps download speed. 03:44.140 --> 03:51.640 Now let's take this particular file, CentOS. 03:52.120 --> 03:59.650 Let's copy the link location and let's do a wget and try to download it. 04:03.050 --> 04:11.390 Now, typically, if you see these are the websites who generally get thousands of users at an instant 04:11.390 --> 04:15.470 of maybe a day who will be downloading all of these files. 04:15.470 --> 04:20.090 So they actually cannot give full speed to all the users. 04:20.090 --> 04:26.540 So they actually have a lot of bandwidth based restrictions on the file. 04:27.260 --> 04:36.230 So here you see, I'm able to download the file at around 600 KB, 600 to 700 KB maximum, even though 04:36.230 --> 04:40.790 I can download it more than 17 Mbps. 04:40.790 --> 04:49.100 But the server has a restriction of around 600 KB, so no one will be able to download this particular 04:49.100 --> 04:53.470 file at speed more than 700 or 600 KB. 04:53.510 --> 04:53.810 S. 04:53.930 --> 04:59.960 So this is something which is very important for the servers who are hosting files to download. 05:01.640 --> 05:07.380 So we'll be doing the same thing for our Nginx machine. 05:07.380 --> 05:09.840 And let's see on how we can do that. 05:13.970 --> 05:18.110 So let's go to the Nginx configuration. 05:30.180 --> 05:36.000 And let's create a new location directive called as downloads. 05:36.000 --> 05:40.500 So I'll say location slash downloads. 05:44.560 --> 05:47.230 The route will be via w-w-w. 05:47.350 --> 05:48.880 Websites. 05:51.260 --> 05:51.950 Example. 05:56.620 --> 05:58.570 And I'll close the director. 06:00.960 --> 06:06.300 Let's save this test if the configuration is okay and it is good. 06:06.510 --> 06:10.950 So let's go to var W-w-w example. 06:11.820 --> 06:12.090 Sorry. 06:12.090 --> 06:13.230 Websites. 06:13.350 --> 06:14.310 Example. 06:15.000 --> 06:17.190 Let's create a folder called as downloads. 06:23.190 --> 06:28.620 And inside downloads will be the file which people will be downloading from. 06:28.620 --> 06:37.140 So we have already downloaded a 100 MB 100 M test file, so let's copy this file from temp directory 06:37.950 --> 06:39.810 to this download directory. 06:50.180 --> 06:54.860 And inside download directory we have a 100 MB 100 mb test file. 06:56.780 --> 06:59.150 That's also reload the nginx. 07:01.090 --> 07:06.720 Okay, so inside the download directory we have a 100 MB file. 07:06.730 --> 07:11.960 So let's use some other server to download the particular file. 07:11.980 --> 07:14.490 So this is my second server. 07:14.500 --> 07:24.940 So what I'll do is I'll go to temp directory and let's do a wget on server, a.com/downloads 07:26.470 --> 07:28.360 followed by the name of the file. 07:30.350 --> 07:33.130 Which is 100 and. 07:35.660 --> 07:36.890 Beta test. 07:42.530 --> 07:44.690 So similarly. 07:47.350 --> 07:52.660 The file has been downloaded and the average download speed is 17 Mbps. 07:52.810 --> 07:59.560 So as there is no restriction, the server was able to download it at full speed. 07:59.590 --> 08:05.500 So now let's use the limit, underscore con module and let's put up restrictions. 08:07.330 --> 08:11.350 So let's go to our nginx. 08:15.240 --> 08:17.940 And inside the download location directive. 08:21.830 --> 08:22.910 Beneath the root. 08:26.730 --> 08:28.440 There is a directive called as. 08:32.800 --> 08:38.890 Limit underscore rate, which let's put it as 50 K. 08:43.560 --> 08:44.700 And let's save it 08:47.160 --> 08:50.190 and let's reload the enginex configuration. 08:52.510 --> 09:01.240 So basically what we have told to Nginx is only allow the file to be downloaded at maximum 50 KB s. 09:01.780 --> 09:05.170 So if I try to download the same file again. 09:09.050 --> 09:16.620 You see from 17 Mbps per second to 50 KB per second. 09:16.640 --> 09:22.130 So this is how basically the restriction on download limit is done. 09:26.280 --> 09:31.140 Now lets me show you some more interesting stuff. 09:31.140 --> 09:34.440 So let's connect to server B. 09:39.710 --> 09:40.190 And use. 09:40.190 --> 09:40.490 Good. 09:45.640 --> 09:53.410 Okay, so this is server A from which we are downloading the file and this is the server B from which 09:53.410 --> 09:55.060 the file is getting downloaded. 09:55.180 --> 10:03.430 So what will happen if I download the same file in server B multiple times? 10:11.170 --> 10:13.120 So let me copy this again. 10:14.350 --> 10:18.070 Let's copy this and let's paste it again. 10:22.070 --> 10:29.870 So you see, there are two connections from same IP address and each connection is able to download 10:30.230 --> 10:32.540 the file at 50 KB. 10:32.540 --> 10:33.050 S. 10:34.340 --> 10:43.280 So if you have, say, ten connections, then essentially you can download 50 into ten connections worth 10:43.280 --> 10:44.120 of speed. 10:44.510 --> 10:47.040 So this is generally not ideal. 10:47.060 --> 10:54.860 So we have to limit the amount of speed that we give to each an individual connection. 10:54.950 --> 10:59.000 So we can also do that with Nginx. 11:01.790 --> 11:08.960 So in order to do that, we have to define a zone similar to similarly to the zone that we had defined 11:08.960 --> 11:12.050 earlier for shared memory and buffer. 11:14.420 --> 11:16.100 Let's define one more zone. 11:16.340 --> 11:20.210 So I'll say limit, underscore, connection, underscore zone. 11:21.200 --> 11:25.640 Here it will be binary, remote. 11:26.540 --> 11:27.260 Addr. 11:31.280 --> 11:32.150 The zone name. 11:32.450 --> 11:34.430 Let's put it as ADR. 11:35.000 --> 11:39.530 And the amount of space that we want to give is, say, ten MB. 11:41.560 --> 11:46.600 So what basically this means is the binary remote ADR. 11:46.720 --> 11:50.350 This is an alternative to remote addr. 11:50.380 --> 11:55.720 Basically, this means the IP address of the client who will be downloading the file. 11:57.480 --> 12:03.930 So in this, let's add one more directive 12:06.270 --> 12:11.490 limit, underscore con ADR one. 12:11.700 --> 12:22.320 So basically what this means is for the downloads directory, a particular IP address can only have 12:22.320 --> 12:24.780 one connection at an instant of time. 12:25.800 --> 12:37.260 So if I save this and if I do a reload and let me do a control C on both the instance. 12:37.560 --> 12:43.380 So let's download the file again over here and you see it is getting downloaded. 12:43.740 --> 12:46.740 Now there is already a connection which is established. 12:46.770 --> 12:53.850 Now if I try to download one more file from this same IP address, basically it will give a file three 12:53.880 --> 13:00.310 because there is already one connection on from a particular IP who is downloading the file. 13:01.030 --> 13:07.270 So this is something that you can do on your production machine. 13:10.810 --> 13:18.290 Now, there is one more interesting directive that you should remember is I'll. 13:20.970 --> 13:21.160 And. 13:24.620 --> 13:27.230 Limit underscore rate underscore after. 13:29.030 --> 13:36.830 So what this basically means is first 50 m allow the user to download it at the maximum speed. 13:37.460 --> 13:41.930 After 50 mb, limit the rate to 50 Mbps. 13:42.830 --> 13:44.600 So I'll save this. 13:45.110 --> 13:47.180 Let's reload the nginx. 13:48.830 --> 13:49.520 And. 13:50.430 --> 13:54.330 Let's control C and let's try downloading the file again. 13:55.020 --> 13:58.020 So now you see the first 50 MB. 13:58.620 --> 14:02.790 It downloaded instantaneously after 50 MB. 14:03.330 --> 14:06.300 The speed will be reduced back to 50 KB. 14:06.300 --> 14:06.840 S. 14:07.560 --> 14:15.240 And this is how a lot of websites specifically for if you try to download a file and if you are not 14:15.240 --> 14:19.290 a premium user, you see there is a bandwidth restriction that you get. 14:19.410 --> 14:24.810 Maybe you will be only be able to download file at 100 KB maximum and so on. 14:25.200 --> 14:31.650 So these are some of the things that you can do with the Http limit underscore module. 14:32.100 --> 14:37.710 So I hope this has been informative for you and I'd like to thank you for viewing.