Configuring AAA Services

Listing 10.1 clears all users from the PIX, creates four users, and shows all the users that exist inside the PIX configuration file.

Listing 10.1 Configuring Username and Passwords

pixfirewall(config)# clear user
pixfirewall(config)# username daniel password 1234 privilege 15
pixfirewall(config)# username kristina password 1234 privilege 15
pixfirewall(config)# username jack password 1234
pixfirewall(config)# username peter password 1234
pixfirewall(config)# show user
username daniel password fOpmsyD0svtnnlr/ encrypted privilege 15
username peter password GCbahPTC/hAylaFE encrypted privilege 2
username kristina password wTsW2QC6pRXaJrTT encrypted privilege 15
username jack password 5zVJhD5YUb6zO7VH encrypted privilege 2

Adding Users with CSACS

To add a user to the CSACS database, you must open the user Web interface. First, you turn on the TACACS+ advanced features so you can configure privileged exec access on your user accounts. The steps to enable these advanced features are as follows :

1. On the left menu, click the Interface Configuration button.

2. Click the TACACS+ (Cisco IOS) link.

3. Scroll down until you find the Advanced Configuration Options section and place a check in the box labeled Advanced TACACS+ Features.

4. Click the Submit button at the bottom of the screen to enable the features.

The following are the steps to create a user account in Cisco Secure ACS:

1. Click the User Setup button from the menu list on the left side.

2. Enter the username daniel into the User: box and click the Add/Edit button.

3. Scroll down to the User Setup section and enter a password of 123456789 .

4. Now scroll down to the Advanced TACACS+ Settings section and select the Max Privilege for Any AAA Client radio button option. Then use the pull-down menu to select level 15. This will provide privilege-level access to the user named daniel .

5. Just below the advanced TACACS+ settings is a section called TACACS+ Enable Password. Select Use CiscoSecure PAP Password. This will use the password you previously set; alternatively, you could set a separate enable password if you wanted.

6. Click the Submit button to save the user.

Now that the usernames have been created, you are ready to configure AAA services on the PIX firewall.

Configuring the aaa-server Command

The aaa-server command is used to configure group tags that define where the AAA server is located. If the AAA server is remote, either RADIUS or TACACS+ security protocols can be used to request the remotely located AAA services. However, if the AAA server is local, no security protocol is required to communicate with the internal PIX configuration file. Table 10.2 describes the three possible locations and protocol used to acquire AAA services.

Table 10.2. aaa-server Locations

The following is the syntax of the aaa-server command:

pixfirewall(config)# [no] aaa-server <group_tag> protocol tacacs+radius
pixfirewall(config)# [no] aaa-server <group_tag> [<(if_name)>] 
               host <ip_address> [<key>]

Table 10.3 displays the possible options for the aaa-serve r command.

Table 10.3. aaa-server Command Options

The following example displays the current aaa-server group tags and then creates a new group tag called PIXAuth . This new group tag configures TACACS+ as the security protocol and 192.168.1.10 as the AAA server:

pixfirewall(config)# show aaa-server
aaa-server TACACS+ protocol tacacs+
aaa-server RADIUS protocol radius
aaa-server LOCAL protocol local

pixfirewall(config)# aaa-server PIXAuth protocol tacacs+
pixfirewall(config)# aaa-server PIXAuth (inside) host 192.168.1.10 dog

Configuring Authentication

AAA authentication can be used to control access into the PIX console, privileged exec mode, and access through the PIX. This section covers console access and access technologies used to control traffic through the PIX.

Authentication and Console Access

Console access requires a username and password. Access methods for AAA authentication to the PIX can be via serial, Telnet, SSH, HTTP, and privileged exec mode. The aaa authentication command syntax is as follows:

pixfirewall(config)# [no] aaa authentication serialtelnetsshhttpenable
               console <group_tag>

Table 10.4 displays the possible options for the aaa-authentication command.

Table 10.4. aaa authentication Options

The following example displays the commands needed to configure the PIX firewall to use a TACACS+ server (192.168.1.10) for console authentication. As users connect via Telnet or enter privileged exec mode, they will be prompted to enter a username and password before allowing them to proceed:

pixfirewall(config)# aaa-server PIXAuth protocol tacacs+
pixfirewall(config)# aaa-server PIXAuth (inside) host 192.168.1.10 dog
pixfirewall(config)# aaa authentication enable console PIXAuth
pixfirewall(config)# aaa authentication telnet console PIXAuth

Authorization and Console Access Commands

Console access can be controlled by the AAA authentication, whereas console commands can be controlled by using AAA authorization. Controlling command access enables the PIX to contain several levels of users, some with full command access (level 15) and others with specifically allocated commands.

The privilege command is used to associate a specific command with a level of access. The command syntax is shown here:

pixfirewall(config)# [no] privilege [{show  clear  configure}] 
               level <level> [mode {enableconfigure}] command <command>

Table 10.5 displays the possible options for the privilege command .

Table 10.5. privilege command Options

The privilege command shown in Listing 10.2 creates two users with different levels of access. Commands designated to access levels 11 and 12 are then assigned.

Listing 10.2 Creating Users and Setting Privilege Mode Commands

pixfirewall(config)# username jimmy password 123456 privilege 11
pixfirewall(config)# username richard password 123456 privilege 12

pixfirewall(config)# privilege show level 11 command access-list
pixfirewall(config)# privilege show level 11 command running-config
pixfirewall(config)# privilege show level 12 command interface

pixfirewall(config)# aaa authorization command LOCAL

In Listing 10.2, because Jimmy has privilege level 11, he will be able to execute any command assigned to level 11 and below. Richard, on the other hand, has a level that is higher and will therefore be able to execute any command associated with level 12 and below. The last aaa authorization command LOCAL designates the local username and password list for command authorization.

Authorization for commands can also be set up using the CSACS Web interface by clicking the Group Setup button, selecting the group options, and setting the commands.

The privilege command enables you to associate a command with an access level.

Authentication for Cut-through Proxy

Using cut-through proxy enables you to control HTTP, FTP, and Telnet services through the PIX firewall. Access lists provide general packet filtering, whereas cut-through proxy requires a username and password before allowing access. For example, if Jack wants to control which users can use HTTP through the PIX, he could implement cut-through proxy and prompt HTTP traffic with a username and password dialog box, as shown in Figure 10.4. This username and password would be forwarded to the AAA server for authentication and authorization using TACACS+ or RADIUS security protocols.

Cut-through proxy works with FTP, HTTP, and Telnet.

The following shows two aaa authentication commands that can be used to implement cut-through proxy:

pixfirewall(config)# [no] authentication includeexclude <service>
                          inboundoutbound <if_name>
                          <internal_ip> <internal_mask>
                          [<external_ip> <external_mask>] <group_tag>

pixfirewall(config)# [no] aaa authentication match <access_list_name>
                          inboundoutbound <if_name> <if_name> <group_tag>

Table 10.6 displays the possible options for the aaa authentication command.

Table 10.6. Cut-through Proxy aaa authentication Command Options

The example shown here enables cut-through proxy authentication on the inside interface:

pixfirewall(config)# aaa-server PIXAuth protocol tacacs+
pixfirewall(config)# aaa-server PIXAuth (inside) host 192.168.1.10 dog
pixfirewall(config)# aaa authentication include http 
               outbound 0 0 0 0 PIXAuth

Cut-through proxy can be used to authenticate both users in the inside interface going out and users coming in on the outside interface.

pixfirewall(config)# [no] authorization includeexclude <service>
                          inboundoutbound <if_name>
                          <internal_ip> <internal_mask>
                          [<external_ip> <external_mask>] <group_tag>

pixfirewall(config)# [no] aaa authorization match <access_list_name>
                          inboundoutbound <if_name> <if_name> <group_tag>

pixfirewall(config)# [no] accounting includeexclude <service>
                          inboundoutbound <if_name>
                          <internal_ip> <internal_mask>
                          [<external_ip> <external_mask>] <group_tag>

pixfirewall(config)# [no] aaa accounting match <access_list_name>
                          inboundoutbound <if_name> <if_name> <group_tag>

pixfirewall(config)# aaa accounting include any inbound 0 0 0 0 PIXAuth
pixfirewall(config)# aaa accounting include any outbound 0 0 0 0 PIXAuth