Home > Articles > Security > Network Security

This chapter is from the book

Task 1: Prepare for IPSec

Successful implementation of an IPSec network requires advance preparation before beginning configuration of individual PIX Firewalls. This section outlines how to determine network design details to configure a PIX Firewall for CA support.

You must plan in advance if you want to configure IPSec encryption correctly the first time and minimize misconfiguration. You should begin this task by defining the IPSec security policy based on the overall company security policy. Some planning steps follow:

Step 1

Determine CA server details—This includes variables such as the type of CA server to be used, the IP address, and the CA administrator contact information.

Step 2

Determine IKE (IKE phase one) policy—Determine the IKE policies between peers based on the number and location of IPSec peers.

Step 3

Determine IPSec (IKE phase two) policy—Identify IPSec peer details such as IP addresses and IPSec modes. You then configure crypto maps to gather all IPSec policy details together.

Step 4

Check the current configuration—Use the write terminal, show isakmp [policy], show crypto map, and many other show commands, which are covered later in this chapter in the "Test and Verify VPN Configuration" section.

Step 5

Ensure that the network operates without encryption—Ensure that basic connectivity has been achieved between IPSec peers using the desired IP services before configuring IPSec. You can use the ping command to check basic connectivity.

Step 6

Ensure that access lists are compatible with IPSec—Ensure that perimeter routers and the PIX outside interfaces permit IPSec traffic. Implicitly permit IPSec packets to bypass PIX access lists and conduits. In this step, you will need to enter the sysopt connection permit-ipsec command.


NOTE

Step 1 and Step 2 are covered in detail in this chapter. The other steps are presented for review purposes. Refer to Chapter 6 for a detailed explanation of Steps 3 through 6.

Step 1: Determine CA Server Details

Successful implementation of an IPSec network requires advanced planning before beginning configuration of individual routers. This section outlines how to prepare for IKE and CA support.

Configuring CA is complicated. Having a detailed plan lessens the chances of improper configuration. Some planning steps include the following:

  • Determine the type of CA server to use—CA servers come in a multitude of configurations and capabilities. You must determine which one fits your needs before configuration. Requirements include, but are not limited to, Rivest, Shamir, and Adelman (RSA) key type; certificate revocation list (CRL) capabilities; and support for Registration Authority (RA) mode.

  • Identify the CA server IP address, host name, and URL—This information is necessary if you will be using Cisco Encryption Technology (CET) and Lightweight Directory Access Protocol (LDAP).

  • Identify the CA server administrator contact information—Arrange for your certificates to be validated if the process is not automatic.

The goal of these planning steps is to be ready for CA support configuration.

You need to have a CA available to your network before you configure CA. The CA must support Cisco's Public Key Infrastructure (PKI) protocol and the Simple Certificate Enrollment Protocol (SCEP).

Figure 7-1 shows an example of CA server details that you should gather before beginning the configuration. The diagram and table in Figure 7-1 illustrate the network topology and CA server details used in this chapter.

Figure 7-1 Determine CA Server Details

Step 2: Determine IKE (IKE Phase One) Policy

You should determine the IKE policy details to enable the selected authentication method, then configure that method. Having a detailed plan lessens the chances of improper configuration. Some planning steps include the following:

  • Determine the key distribution method—Determine the key distribution method based on the numbers and locations of IPSec peers. For small networks, you might wish to manually distribute keys. For larger networks, you might wish to use a CA server to support scalability of IPSec peers. You must then configure Internet Security Association Key Management Protocol (ISAKMP) to support the selected key distribution method.

  • Determine the authentication method—Choose the authentication method based on the key distribution method. The PIX Firewall supports either preshared keys, RSA encrypted nonces, or RSA signatures to authenticate IPSec peers. This chapter focuses on using RSA signatures.

  • Identify IPSec peer's IP addresses and host names—Determine the details of all the IPSec peers that will use ISAKMP and RSA signatures for establishing SAs. You will use this information to configure IKE.

  • Determine ISAKMP policies for peers—An ISAKMP policy defines a combination, or suite, of security parameters to be used during the ISAKMP negotiation. Each ISAKMP negotiation begins by each peer agreeing on a common (shared) ISAKMP policy. The ISAKMP policy suites must be determined in advance of configuration. You must then configure IKE to support the policy details you determined. Some ISAKMP policy details include the following:

    • Encryption algorithm

    • Hash algorithm

    • IKE SA lifetime

An IKE policy defines a combination of security parameters used during the IKE negotiation. A group of policies makes up a protection suite of multiple policies that enable IPSec peers to establish IKE sessions and establish SAs with minimal configuration.

Creating IKE Policies for a Purpose

IKE negotiations must be protected, so each IKE negotiation begins by each peer agreeing on a common (shared) IKE policy. This policy states which security parameters will be used to protect subsequent IKE negotiations.

After the two peers agree upon a policy, the security parameters of the policy are identified by an SA established at each peer. These SAs apply to all subsequent IKE traffic during the negotiation.

You can create multiple prioritized policies at each peer to ensure that at least one policy will match a remote peer's policy.

Defining IKE Policy Parameters

You can select specific values for each IKE parameter per the IKE standard. You choose one value over another, based on the security level you desire and the type of IPSec peer to which you will connect. There are five parameters to define in each IKE policy, as outlined in Table 7-1 and Figure 7-2. Table 7-1 shows the default values of each parameter, and Figure 7-2 shows the relative strengths.

Table 7-1 IKE Policy Parameters

Parameter

Accepted Values

Keyword

Default

Message encryption algorithm

DES

3DES

des

3des

DES

Message integrity (hash) algorithm

SHA-1 (HMAC variant)

MD5 (HMAC variant)

sha

md5

SHA-1

Peer authentication method

Preshared keys

RSA signatures

preshare

rsa-sig

RSA signatures

Key exchange parameters (Diffie-Hellman group identifier)

768-bit Diffie-Hellman or

1024-bit Diffie-Hellman

1

2

768-bit Diffie-Hellman

ISAKMP-established SA's lifetime

Can specify any number of seconds

_

86,400 seconds (one day)


Figure 7-2 IKE Policy Example

You can select specific values for each ISAKMP parameter using the ISAKMP standard. You choose one value over another based on the security level you desire and the type of IPSec peer to which you will connect. There are five parameters to define in each IKE policy, as presented in Table 7-2. Table 7-2 shows the relative strength of each parameter. You can select specific values for each ISAKMP parameter using the ISAKMP standard.

Table 7-2 ISAKMP Parameters

Parameter

Strong

Stronger

Message encryption algorithm

DES

3DES

Message integrity (hash) algorithm

MD5

SHA-1

Peer authentication method

Preshare

RSA Encryption

RSA Signature

Key exchange parameters (Diffie-Hellman group identifier)

D-H Group 1

D-H Group 2

ISAKMP-established SA's lifetime

86,400 seconds

Less than 86,400 seconds


You should determine IKE policy details for each IPSec peer before configuring IKE. Figure 7-2 shows a summary of some IKE policy details that will be configured in examples in this chapter. The authentication method of RSA signatures is used for CA support.

NOTE

Refer to Chapter 6 for a detailed explanation of Steps 3 through 6.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT 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 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@informit.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 InformIT. 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.informit.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