Home > Articles > Cisco Network Technology > General Networking > Cisco Firewall Configuration Fundamentals

Cisco Firewall Configuration Fundamentals

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: Jul 8, 2011.

Chapter Description

This chapter describes the configuration fundamentals for IOS and ASA-based firewalls, highlighting the similarities between the product families.

From the Book

Cisco Firewalls

Cisco Firewalls

$69.99

IOS Baseline Configuration

This section covers some basic concepts of the IOS CLI, most of which are in close proximity to ASA. Example 3-19 displays the summary boot sequence for a router that had no initial configuration. A successful OS image load culminates in the offer of configuring the device through interactive menus (initial configuration dialog), which was refused in this case. After that, the default EXEC (nonprivileged) Router> mode appears. As previously studied for ASA, the default enable password, whose usage provides access to privileged mode, is BLANK, meaning there is no password and that you just need to press Enter.

Example 3-20, the IOS counterpart of Example 3-3, registers a typical show version output for a Cisco router. Some relevant information that can be obtained from this output includes OS version, physical interfaces, and the amount of memory (RAM, Flash, and NVRAM). The last line of the output informs the value of the Configuration Register, an important boot control parameter. For instance, an HEX value of 2102 for this variable instructs the router to boot using the image stored on its Flash memory and obey what is determined by its startup-config, which is saved in the nonvolatile memory (NVRAM).

Example 3-19. Summary Boot Sequence for an IOS Router

System Bootstrap, Version 12.3(8r)YI, RELEASE SOFTWARE
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2005 by cisco Systems, Inc.
C870 series (Board ID: 3-148) platform with 131072 Kbytes of main memory

Booting flash:/c870-advipservicesk9-mz.124-24.T1.bin
Self decompressing the image : ############################################################################################ [OK]
[output suppressed]
Cisco IOS Software, C870 Software (C870-ADVIPSERVICESK9-M), Version 12.4(24)T1, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Sat  20-Jun-09 02:20 by prod_rel_team
[output suppressed]
Installed image archive
Cisco 871W (MPC8272) processor (revision 0x100) with 118784K/12288K bytes of memory.
Processor board ID FHK093310A5
MPC8272 CPU Rev: Part Number 0xC, Mask Number 0x10
5 FastEthernet interfaces
1 802.11 Radio
128K bytes of non-volatile configuration memory.
24576K bytes of processor board System flash (Intel Strataflash)

--- System Configuration Dialog ---

Would you like to enter the initial configuration dialog? [yes/no]: no
Press RETURN to get started!
*Mar  1 00:00:05.579: %VPN_HW-6-INFO_LOC: Crypto engine: onboard 0  State changed to: Initialized
*Mar  1 00:00:05.583: %VPN_HW-6-INFO_LOC: Crypto engine: onboard 0  State changed to: Enabled
[output suppressed]
Router>
Router>enable
Router#

Example 3-20. Sample show version Command for IOS

Router# show version
Cisco IOS Software, C870 Software (C870-ADVIPSERVICESK9-M), Version 12.4(24)T1,
RELEASE SOFTWARE (fc3)
[output suppressed]
ROM: System Bootstrap, Version 12.3(8r)YI, RELEASE SOFTWARE
Router uptime is 2 minutes
System returned to ROM by power-on
System image file is "flash:c870-advipservicesk9-mz.124-24.T1.bin"
[output suppressed]
Cisco 871W (MPC8272) processor (revision 0x100) with 118784K/12288K bytes of memory.
Processor board ID FHK093310A5
MPC8272 CPU Rev: Part Number 0xC, Mask Number 0x10
5 FastEthernet interfaces
1 802.11 Radio
128K bytes of non-volatile configuration memory.
24576K bytes of processor board System flash (Intel Strataflash)
Configuration register is 0x2102 Router#

Configuring Interfaces on IOS Routers

IOS interface configuration is simpler than that of ASA-based products, and does not define, for example, information such as nameif and security-level, two concepts that lie at the core of ASA philosophy. Example 3-21 brings two possibilities for IOS interfaces:

  • Configuration of logical parameters directly under the physical interface.
  • Configuration of 802.1Q subinterfaces, enabling many logical subnets to be tied to one physical interface.

Example 3-21. Basic Interface Configuration Tasks

! Configuring logical attributes directly on the physical interface

interface FastEthernet4
 description *** DMZ interface ***
 ip address 192.168.1.201 255.255.255.0
 speed 100
 duplex full
 no shutdown
!
! Creating 802.1Q (Dot1Q) subinterfaces

interface FastEthernet4
 speed 100
 duplex full
 no ip address
 no shutdown
!
interface FastEthernet4.100
 description *** DMZ interface (VLAN 100) ***
 encapsulation dot1q 100
 ip address 192.168.1.201 255.255.255.0
6. Remote Management Access to IOS Devices | Next Section Previous Section

Cisco Press Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Cisco Press and its family of brands. I can unsubscribe at any time.

Overview

Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Cisco Press products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@ciscopress.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security

Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children

This site is not directed to children under the age of 13.

Marketing

Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out

Users can always make an informed choice as to whether they should proceed with certain services offered by Cisco Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.ciscopress.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links

This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020