qr code c# tutorial 22: Access Control Lists in Objective-C

Encoder QR in Objective-C 22: Access Control Lists

22: Access Control Lists
Denso QR Bar Code Maker In Objective-C
Using Barcode generation for iPhone Control to generate, create QR Code ISO/IEC18004 image in iPhone applications.
Paint Bar Code In Objective-C
Using Barcode encoder for iPhone Control to generate, create bar code image in iPhone applications.
As you can see, configuring ACLs can be tricky For the preceding example, here s the updated configuration:
Creating QR In Visual C#
Using Barcode creator for Visual Studio .NET Control to generate, create QR Code 2d barcode image in VS .NET applications.
Draw QR Code JIS X 0510 In .NET Framework
Using Barcode generation for ASP.NET Control to generate, create QR Code 2d barcode image in ASP.NET applications.
Router(config)# access-list 2 deny 19216810 000255 Router(config)# access-list 2 deny 1721600 00255255 Router(config)# access-list 2 permit 19216811 Router(config)# access-list 2 permit 0000 255255255255 Router(config)# interface ethernet 0 Router(config-if)# ip access-group 1 out
Draw QR Code ISO/IEC18004 In Visual Studio .NET
Using Barcode creator for VS .NET Control to generate, create QR Code image in .NET applications.
QR Code Creation In VB.NET
Using Barcode generator for Visual Studio .NET Control to generate, create QR Code image in .NET applications.
In this example, the first statement now says that any packet with a source address from network 19216810/24 should be dropped The second statement will drop any traffic from the Class B network 1721600/16 The third statement will permit traffic from 19216811 The fourth statement will permit traffic from anywhere Actually, there is still a problem with this configuration look at the first and third statements Will the third statement ever be executed If you answered no, you are correct In this situation, you need to put the more specific entry before the less specific one Another minor point to make is that the fourth statement in the list could represent the address as the keyword any Here s the updated configuration:
Drawing Barcode In Objective-C
Using Barcode maker for iPhone Control to generate, create barcode image in iPhone applications.
Generate Bar Code In Objective-C
Using Barcode generation for iPhone Control to generate, create barcode image in iPhone applications.
Router(config)# access-list 2 permit 19216811 Router(config)# access-list 2 deny 19216810 000255 Router(config)# access-list 2 deny 1721600 00255255 Router(config)# access-list 2 permit any Router(config)# interface ethernet 0 Router(config-if)# ip access-group 1 out
Paint ANSI/AIM Code 39 In Objective-C
Using Barcode generation for iPhone Control to generate, create Code39 image in iPhone applications.
GTIN - 128 Creation In Objective-C
Using Barcode printer for iPhone Control to generate, create UCC - 12 image in iPhone applications.
There s actually one more problem with this ACL If you guessed the ACL number used on the interface is not correct, then you guessed correctly Notice that the ACL created has a number of 2, while the application of the ACL on the interface uses 1 To fix this, use the following configuration:
Making UPC Code In Objective-C
Using Barcode creation for iPhone Control to generate, create Universal Product Code version A image in iPhone applications.
Drawing Bar Code In Objective-C
Using Barcode generator for iPhone Control to generate, create barcode image in iPhone applications.
Router(config)# interface ethernet 0 Router(config-if)# no ip access-group 1 out Router(config-if)# ip access-group 2 out
UPC - 8 Generator In Objective-C
Using Barcode creation for iPhone Control to generate, create GS1 - 8 image in iPhone applications.
USS-128 Drawer In VB.NET
Using Barcode generator for VS .NET Control to generate, create USS-128 image in .NET framework applications.
Note that you must first remove the old ACL from the interface before applying the new ACL
Creating UCC-128 In C#
Using Barcode generation for Visual Studio .NET Control to generate, create GS1-128 image in .NET applications.
USS Code 128 Maker In Java
Using Barcode drawer for Java Control to generate, create Code 128 Code Set B image in Java applications.
Be able to troubleshoot ACL con gurations by examining the order of statements in the listThe
Encoding Code 128 Code Set A In .NET
Using Barcode creation for Reporting Service Control to generate, create ANSI/AIM Code 128 image in Reporting Service applications.
GS1 - 12 Scanner In Visual C#.NET
Using Barcode decoder for .NET framework Control to read, scan read, scan image in .NET framework applications.
preceding example with miscon gured ACL statements is an excellent example of issues to look for in con guring ACLs
Barcode Reader In Java
Using Barcode Control SDK for BIRT Control to generate, create, read, scan barcode image in BIRT reports applications.
Paint Universal Product Code Version A In Java
Using Barcode maker for Eclipse BIRT Control to generate, create UPCA image in Eclipse BIRT applications.
ACL Types
Restricting VTY Access to the Router
In addition to using standard IP ACLs to filter traffic as it enters and/or leaves an interface, you can also use them to restrict VTY access (telnet and SSH) to your router You might want to do this to allow only network administrators to access the CLI of your IOS device remotely Setting this up is almost the same as setting up restricted access on an interface First, you need to create a standard ACL that has a list of permit statements that allow your corresponding network administrators remote access; include the IP addresses of their PCs in this list Next, you need to activate your ACL However, you will not do this on any of the router s interfaces If you were to activate this ACL on an interface, it would allow any type of traffic from your administrators but drop all other traffic As you may recall from 17, when someone telnets or SSH s into your router, the router associates this connection with a virtual type terminal (VTY) line Therefore, you ll apply your standard ACL to the VTYs, like this:
Router(config)# line vty 0 4 Router(config-line)# access-class standard_ACL_# in|out
Remember that your router supports five telnets by default (0 4), and more on certain IOS devices You can configure all VTYs simultaneously by specifying the beginning and ending line numbers after the vty parameter If you don t apply the restriction to all of your VTYs, you are leaving a backdoor into your router, which might cause a security problem Also, notice the command used to apply the ACL to the line: access-class This is different from activating an ACL on a router s interface If you use the in parameter, you are restricting telnet and SSH access to the router itself The out parameter is kind of unique By using this parameter, you are restricting what destinations this router can telnet or SSH to when someone uses the telnet, connect, or ssh commands This creates an exception to a standard ACL and has the router treat the address in the ACL statements as a destination address; it causes the router to compare this address to the address in the telnet command before allowing the user on the router to telnet to the specified destination Here s a simple example of using a standard ACL to filter telnet traffic to a router:
Router(config)# access-list 99 permit 19216810 000255 Router(config)# line vty 0 4 Router(config-line)# access-class 99 in
In this example, only traffic from 19216810/24 is allowed to telnet or SSH into this router Because of the implicit deny at the end of access-list 99, all other connections to this router (via the VTYs) will be dropped
Copyright © OnBarcode.com . All rights reserved.