1 00:00:01,500 --> 00:00:06,930 So let us begin with the first security filtering technique that is access control list. 2 00:00:07,590 --> 00:00:12,380 It's rare to find a network around these days that aren't connected to the Internet. 3 00:00:12,990 --> 00:00:18,330 The Internet is clearly a public Internet tool that anyone can connect to. 4 00:00:18,570 --> 00:00:24,240 But your companies or postal network is and should be definitely a private one. 5 00:00:24,930 --> 00:00:30,840 The catch is that every time you connect to the Internet from a public network, they're instantly vulnerable 6 00:00:30,840 --> 00:00:32,250 to security beacons. 7 00:00:32,880 --> 00:00:36,540 Now, this is where something we call a firewall comes into play. 8 00:00:37,110 --> 00:00:43,650 Firewalls are basically tools that you can implement to prevent any unauthorized access around on public 9 00:00:43,650 --> 00:00:44,220 networks. 10 00:00:44,430 --> 00:00:52,470 And gaining access to a network of the firewalls can either be standalone devices or combined with another 11 00:00:52,470 --> 00:00:55,080 hardware device like servers or routers. 12 00:00:55,950 --> 00:01:02,340 Now, access control list is the primary weapon of the firewalls which help us to, you know, discard 13 00:01:02,340 --> 00:01:03,480 unused packets. 14 00:01:04,830 --> 00:01:10,200 Now, access control list, that is ECL is typically the list. 15 00:01:10,620 --> 00:01:17,250 It's not kind of a list, but it kind of a program that resides on the routers to determine which packets 16 00:01:17,250 --> 00:01:24,030 are allowed to run through them based on the requesting devices, source or destination Internet protocol 17 00:01:24,030 --> 00:01:24,630 address. 18 00:01:24,930 --> 00:01:26,340 That is the IP address. 19 00:01:26,940 --> 00:01:34,200 Oh, and just so you know, issues have been around for many decades and have other uses apart from 20 00:01:34,200 --> 00:01:35,700 firewalls as well. 21 00:01:36,660 --> 00:01:42,240 Now there's an image on the screen which demonstrates an ACL enabled router. 22 00:01:42,990 --> 00:01:46,280 OK, so what we can see here is I like my pen. 23 00:01:46,860 --> 00:01:54,420 What we can see here is that users in the network e that they can access Network B, right. 24 00:01:56,120 --> 00:02:02,830 Also, the package that can pass through the router are from this week from network to Network B. 25 00:02:03,500 --> 00:02:10,560 Now, this means that an IP spoofing attack, when someone pretends to have a network address on the 26 00:02:10,560 --> 00:02:18,720 inside of the firewall to gain the network, access can still happen if a user in the Network B pretends 27 00:02:18,720 --> 00:02:20,550 to be located in the network. 28 00:02:21,090 --> 00:02:28,770 So, for example, someone who is here but it is pretending to be here can also access the Internet 29 00:02:28,770 --> 00:02:37,050 network because it is pretending that it's actually residing here now will see things like IP spoofing 30 00:02:37,050 --> 00:02:41,590 more thoroughly in other sections of network threat and mitigation. 31 00:02:41,880 --> 00:02:44,670 But for now, let's go back to Israel. 32 00:02:45,600 --> 00:02:54,090 So which means B can access E if a secure authentication connection is so, B, can actually access 33 00:02:54,090 --> 00:02:54,510 A. 34 00:02:55,450 --> 00:03:00,820 Only if a secure authentication connection is used, for example. 35 00:03:02,950 --> 00:03:05,710 But it can access the public network. 36 00:03:07,430 --> 00:03:13,850 Now you can create a wide array of access control lists from the very simple to the highly complex, 37 00:03:14,270 --> 00:03:19,190 depending on the exact what do you exactly want to have them to do for you? 38 00:03:20,000 --> 00:03:27,590 One example is placing separate inbound and outbound access control on in order to ensure that the data 39 00:03:27,830 --> 00:03:34,030 that is leading your network comes from a different source than the data that's coming into it. 40 00:03:34,880 --> 00:03:41,240 Now, when configuring access control lists between the Internet and your private network to mitigate 41 00:03:41,240 --> 00:03:49,550 security problems, it is a good idea to deny any address from your internal networks, then deny any 42 00:03:49,550 --> 00:03:50,990 localhost addresses. 43 00:03:51,000 --> 00:03:59,180 That is 127 DOT zero zero eight and deny any reserved private addresses. 44 00:04:00,110 --> 00:04:07,190 Deny any addresses in the IP multicast address range that is to twenty four point zero point zero slash. 45 00:04:07,520 --> 00:04:12,710 For now, none of these addresses should ever be allowed to your Internet. 46 00:04:13,700 --> 00:04:20,690 Interestingly enough, because of the way in which in public IP addresses are issued with some research, 47 00:04:20,690 --> 00:04:29,600 you can even create a filter that blocks a country, a state or even a local area based on the IP addresses. 48 00:04:30,170 --> 00:04:35,720 If you want to know more about access control list, I guess I have already attached some resources 49 00:04:35,720 --> 00:04:37,040 at the beginning of the section. 50 00:04:37,040 --> 00:04:40,550 If I have not, please post a question and answer in the question. 51 00:04:40,550 --> 00:04:41,270 Answer section. 52 00:04:41,570 --> 00:04:43,770 I will immediately upload the book. 53 00:04:45,770 --> 00:04:47,460 Well, that is it for this lecture. 54 00:04:47,630 --> 00:04:54,140 I hope you have understand the function of access control list and why access control lists are important.