Cisco asa object network

Imagine you have to manage a Cisco ASA firewall that has hundreds of hosts and dozens of servers behind it, and for each of these devices we require access-list rules that permit or deny traffic. With so many devices you will have a LOT of access-list statements and it might become an administrative nightmare to read, understand and update the access-list.

Instead of creating an access-list with many different statements we can refer to an object-group. This makes the access-list smaller and easier to read. Whenever you make changes in the object-group, these are also reflected in the access-list.

We will take a look at a couple of examples and you will see why object groups are very useful. Our access-list could look like this:. This will work but we require 5 statements in our access-list. I reduced the access-list from five statements to just one statement. Instead of specifying each IP address separately, I refer to the object-group. This is useful right? If you look in the configuration you will find this single entry:. However if you look at the access-list, it will show you both the object-group and the specific entries:.

The previous example should give you a good idea how you can use object groups to make your access-list smaller. This does the job but now we have 4 statements…one for each TCP port.

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Instead of specifying the TCP port in each statement, we will create another object-group that combines all our TCP ports. Explained As Simple As Possible. Full Access to our Lessons. More Lessons Added Every Week! Tags: ACLSecurity. Let me give you an example:. The access-list above only has one line.

When you take a closer look, you can see there are quite some statements:. So it kinda makes sense to use the service object group in the beginning since you specify the protocol with it.

The big difference is that is also includes the port numbers which we normally end at the end of the statement. These can be difficult to read if you find them in the running configuration. If you use the show access-list command, you can see the exact statements that are in effect. For example:. Ask a question or join the discussion by visiting our Community Forum. Skip to content Search for: Search.

You may cancel your monthly membership at any time. No Questions Asked! Continue reading in our forum. Thanks Rene, I got that but a doubt strike me - lets start with the below configuration: network object TEST1 subnet Hi Matt, I see what you mean. Normally the format of an extended access-list statement looks like this: So it kinda makes sense to use the service object group in the beginning since you specify the protocol with it.

Hi Jeff, These can be difficult to read if you find them in the running configuration.Enter an object name. Select Create a network object. Select range and then enter a range of IP addresses. Enter the range with the beginning and ending address in the range separated by a space. For example, Click Add. If you want your network group to be made up of network objects, use the Create a Network Object procedure above to create individual network objects for your IP addresses.

Click the Objects tab to open the Objects page. Continue to do this until you have added all the network objects you want.

Click Add Another Value and then add another IP address in the Value field until you have added all the values you want. Click Add when you are done. Bulk entry : In the Values area, click Show Advanced. Paste into the text box a list of IP addresses or subnet addresses separated by a newline, space, comma, or semicolon and then click Done. Locate the object you want to edit by using object filters and search field.

Select the object you want to edit. Edit the values in the dialog box in the same fashion that you created them in the procedures above.Although NAT can be defined more as a functional feature translating a private IP address space to a smaller public IP address spaceit can also be seen as a security feature hiding real IP addresses. These are not formal definitions but if you are familiar with the Cisco ASA, then you know things changed drastically between ASA version 8.

Those were dark days…. Starting with ASA version 8. Dynamic NAT allows translating a group of real addresses to a pool of mapped addresses. Usually, the mapped addresses are fewer in number than the real addresses; however, this is based on your traffic expectation.

Imagine you have a network with three sides as in our lab setup: inside, dmz and outside. Dynamic NAT is suitable in this kind of scenario. So how do we configure it? First, we need to create a network object for the real addresses i. Then, we will also create a network object for the mapped addresses i. Finally, we configure our NAT rule to tie both of them together.

There are a couple of things to discuss in the configuration above.

cisco asa object network

First, notice that Network Object NAT is configured under a network object hence the name — it is configured under the network object that defines the real addresses. The difference between dynamic and static translation is that traffic initiation in one is unidirectional while the other can be bidirectional.

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We will talk more about this later. We can use the show xlate command on the ASA to see this translation:. Note that this translation will be active for as long as the connection is active; when the Telnet session is ended, the translation will be removed after the timeout.

This means that hosts on the destination network cannot initiate the connection to hosts on the real network. That is why we say traffic initiation in Dynamic NAT is unidirectional. Note : It is possible for a host on the destination network to initiate a connection to a host on the real network as long as there is already a translation entry on the Cisco ASA.

However, this is usually not practical because the host on the destination network will need to know the exact mapped IP address of the real host which changes and the connection will need to be allowed by an access rule. Dynamic PAT is similar to dynamic NAT except that it is used to translate multiple real addresses to just one mapped address or multiple mapped addresses in a pool. It works by using ports for the translation — the real address and source port is translated to the mapped address and a unique port.

Dynamic PAT is ideal when you want to give an internal network access to the Internet. Because public IP addresses are scarce and expensive, you would normally translate the private IP addresses of all users on your internal network to a single public IP address that is routable on the Internet.

One of the benefits of this is that traffic can be initiated in a bidirectional manner. For a real world application of Static NAT, imagine you have a web server in your DMZ that should be accessible from the Internet; you will configure Static NAT so that both the server and outside users can initiate traffic in either direction. We can test our configuration in either direction: dmz to outside or outside to dmz:.

I hope you enjoyed this article and found it insightful. Thanks a lot Adeolu. I have read and watched many tutorials and videos, but you have the simplest and cleanest explanation. I had been struggling with getting these concepts down, but now that I see them laid out clearly, and a legit use case to follow, they make total sense now, awesome job man! Great examples. Thanks for sharing. Your email address will not be published.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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Home Questions Tags Users Unanswered. ASA access-list to object group Ask Question. Asked 1 year, 1 month ago. Active 1 year, 1 month ago. Viewed times. Kyle Rogers. Kyle Rogers Kyle Rogers 1 1 silver badge 8 8 bronze badges. Not really, since you don't have all of the sources talking to all of the same destinations.

You could make a couple different groups but it won't really make it easier to manage in this case. Mar 1 '19 at I added an answer so I could provide proper formatting and make it easier to read. Thank you. Mar 14 '19 at Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer. Active Oldest Votes. So, you can remove those 2 lines.

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Jesse P. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.This chapter describes how to use the ASDM user interface. The ASDM user interface includes the following elements:.

A menu bar that provides quick access to files, tools, wizards, and help. Many menu items also have keyboard shortcuts. A toolbar that enables you to navigate ASDM.

From the toolbar you can access the HomeConfigurationand Monitoring panes. You can also get help and navigate between panes. A dockable left Navigation pane to move through the Configuration and Monitoring panes. You can click one of the three buttons in the header to maximize or restore this pane, make it a floating pane that you can move, hide it, or close it. To access the Configuration and Monitoring panes, you can do one of the following:. Click links on the left side of the application window in the left Navigation pane.

If you know the exact path, you can type it directly into the title bar of the Content pane on the right side of the application window, without clicking any links in the left Navigation pane. A maximize and restore button in the right corner of the Content pane that lets you hide and show the left Navigation pane. A status bar that shows the time, connection status, user, memory status, running configuration status, privilege level, and SSL status at the bottom of the application window.

A left Navigation pane that shows various objects that you can use in the rules tables when you create access rules, NAT rules, AAA rules, filter rules, and service rules. The tab titles within the pane change according to the feature that you are viewing.

ASDM Book 2: Cisco ASA Series Firewall ASDM Configuration Guide, 7.1

The following figure shows the elements of the ASDM user interface. To view tool tips, hover your mouse over a specific user interface element, such as an icon in the status bar. To move efficiently throughout the ASDM user interface, you may use a combination of menus, the toolbar, dockable panes, and the left and right Navigation panes, which are described in the previous section.

The available functions appear in a list of buttons below the Device List pane. An example list could include the following function buttons:.

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Botnet Traffic Filter. Remote Access VPN. Site to Site VPN. Device Management. The list of function buttons that appears is based on the licensed features that you have purchased. Click each button to access the first pane in the selected function for either the Configuration view or the Monitoring view. The function buttons are not available in the Home view.This article assumes prior knowledge of each of these concepts.

If you need a refresher, please check out the article series. There are two sets of syntax available for configuring address translation on a Cisco ASA. The syntax for both makes use of a construct known as an object. The configuration of objects involve the keywords real and mapped.

cisco asa object network

In Part 1 of this article we will discuss all five of these terms. An object is a construct which represents any single item in your network environment. Two types of objects can be configured:. To configure a network objectfirst use the following syntax to create the object:.

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To create a network object which represents your Inside network, you would use the following syntax:. Lastly, to create a network object which represents a particular IP address range, you would use the following syntax. This will define a range that includes all five IP addresses in the inclusive range of To configure a service objectfirst use the following syntax to create the object:.

The content of the service object must include at least a protocol, and can also include a source port, destination port, or both. Here are examples of all four possibilities:. The specific port number the object represents can be identified using certain operators — the example above uses eq and gt.

Five different operators exists:. The show run object command lists the objects essentially as they were configured above:.

And the show run object in-line command displays the same as above, except every object definition will be on the same line as the object name:.

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These terms can be applied to IP addresses or interfaces. We will define these with the example of a Static NAT below:. The word real indicates what is really configured on a server. For example, the web server at the IP address. Hence, Hence, for the translation above, the Inside interface is considered the real interface.

How to Configure Static NAT on a Cisco ASA: Cisco ASA Training 101

The word mapped indicates attributes after a translation has occurred. For example, the real address Which makes In previous lessons I explained how you can use dynamic NAT or PAT so that your hosts or servers on the inside of your network are able to access the outside world.

What if an outside host on the Internet wants to reach a server on our inside or DMZ? When we want to achieve this we have to do two things:. This configuration is for ASA version 8.

The eight most important commands on a Cisco ASA security appliance

This takes care of NAT but we still have to create an access-list or traffic will be dropped:. The access-list above allows any source IP address to connect to IP address When using ASA version 8.

This enables the access-list on the outside interface. Above you can see the static NAT entry and also the hit on the access-list. Everything is working as it is supposed to be.

The previous example was fine if you have only a few servers since you can create a couple of static NAT translations and be done with it. Explained As Simple As Possible.

cisco asa object network

Full Access to our Lessons. More Lessons Added Every Week! Tags: NATSecurity.

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When The only thing the ASA cares about is what to translate. Thanks sorted out this problem. This statement will cause a translation from host This translation functions both ways, meaning that when I have already ask you guys below question in different forum.

It works through above NAT rule only. We are configuring new ASA and this is our topology. Ask a question or join the discussion by visiting our Community Forum. Skip to content Search for: Search.

When we want to achieve this we have to do two things: Configure static NAT so that the internal server is reachable through an outside public IP address.

Configure an access-list so that the traffic is allowed. Static NAT for entire subnet The previous example was fine if you have only a few servers since you can create a couple of static NAT translations and be done with it. We can use this pool to translate all the servers in the DMZ, let me show you how:. You may cancel your monthly membership at any time. No Questions Asked!


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