Configuring Access to Internal Resources

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Configuring Access to Internal Resources

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What is ISA server publishing?

• Publish internal servers to the Internet, so that users on the Internet can access those internal resources

• Making internal resources accessible to the Internet increases the security risks for the organization.

• ISA Server uses Web and server publishing Web and server publishing rules rules to publish internal network resources to the Internet

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Client Internet

Web ServerWeb Server

Mail ServerMail Server

File ServerFile Server

Remote UserRemote User

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Mail ServerMail ServerFile ServerFile Server

ISA server

Internal Network

Using a perimeter network is to Using a perimeter network is to provide an additional layer ofprovide an additional layer ofSecurity!!!Security!!!

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What Are Web Publishing Rules?

• Make Web sites on protected networks available to users on other networks, such as the Internet

• A Web publishing rule is a firewall rule that specifies how ISA Server will route incoming requests to internal Web servers

• Web Publishing is sometimes referred to as “reverse proxyingreverse proxying”.

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What do Web publishing rules provide?

• Access to Web servers running HTTP protocol• HTTP application-layer filtering• Path mapping• User authentication• Content caching• Support for publishing multiple Web sites

using a single IP address• Link translation

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What Are Server Publishing Rules

• Web publishing and secure Web publishing rules can grant access only to Web servers using HTTP or HTTPS.

• To grant access to internal resources using any other protocol, you must configure server publishing rulesserver publishing rules!!!!!!

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What do Server publishing rules provide?

• Access to multiple protocols• Application-layer filtering for

specified protocols• Support for encryption• IP address logging for the client

computer

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Considerations for Configuring DNS for Web and Server Publishing


ISA server

Internal Network

IP address 172.16.10.1IP address 172.16.10.1

External IP address

131.107.1.1

External IP address

131.107.1.1

http://isalab.com

A split DNS uses two different DNS servers with the same DNS domain name to providename resolution for internally and externally accessible resources!

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Configuring Web Publishing Rules

• Web Listener• Non-SSL Web Publishing Rules• SSL Web Publishing Rules

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Web Listener• Web listeners are used by Web and secure

Web publishing rules• A Web listener is an ISA Server configuration

object that defines how the ISA Server computer listens for HTTP requests and SSL requests

• All incoming Web requests must be received by a Web listener

• A Web listener may be used in multiple Web publishing rules

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Web Listener


ISA server

Internal Network

IP address 172.16.10.1IP address 172.16.10.1

External IP address

131.107.1.1

External IP address

131.107.1.1

http://isalab.com

Web ListenerWeb Listener

Web ListenerWeb Listener

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How to Configure Web Listeners

• Network• Port numbers• Client authentication methods• Client Connection Settings

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NetworkIf you have multiple network adapters or multiple IP addressesIf you have multiple network adapters or multiple IP addresses

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Port numbers

By default, the Web listener will listen on for HTTP requests on Port 80By default, the Web listener will listen on for HTTP requests on Port 80

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How to Configure Web ListenersWeb listener “listens” on aninterface or IP address that you choose for incoming connections to the port you define

Web listener “listens” on aninterface or IP address that you choose for incoming connections to the port you define

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Configuring Non-SSL Web Publishing Rules

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Rule Action PageRule Action Page

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• Publishing Type Page– Publish a single Web

site or load balancer– Publish a server farm

of load balanced Web Servers

– Publish multiple web sites

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• The Server Connection Security Page:

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• The Internal Publishing Details Page:– Internal Site Name– Computer name or IP

address

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• The Internal Publishing Details Page:– Path Name– Forward the original

host header instead of the actual one

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• The Public Name Details Page– Accept requests

for– Public Name– Path (optional

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• The Select Web Listener Page and Creating an HTTP Web Listener:– Edit– New

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• The Authentication Settings Page

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Web Listener Authentication Methods

• Basic• Digest• Integrated• RADIUS• RADIUS OTP• SecurID• OWA Forms-based• Forms-Based Authentication• SSL Certificate

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• The Single Sign on Settings Page

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• The Authentication Delegation Page

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Secure Web Publishing

Client Internet


Remote UserRemote User

Encrypted content

Encrypted content

More More secure!!secure!!

More More secure!!secure!!

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Cryptography issues• Only sender, intended receiver should

“understand” message contents– sender encrypts message– receiver decrypts message

ReceiverReceiver

SenderSender DecryptDecryptEncryptEncrypt

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Types of Cryptography

• Crypto often uses keys:– Algorithm is known to everyone– Only “keys” are secret

• Public key cryptography – Involves the use of two keys

• Symmetric key cryptography– Involves the use one key

• Hash functions– Involves the use of no keys– Nothing secret: How can this be useful?

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Secret-Key or Symmetric Cryptography

Sender and Receiver agree on an encryption method and a shared key

Sender and Receiver agree on an encryption method and a shared key

Send encrypted message

Sender uses the key and the encryption

method to encrypt (or encipher) a message

Sender uses the key and the encryption

method to encrypt (or encipher) a message

Receiver uses the same key and the related decryption method to decrypt (or decipher) the message.

Receiver uses the same key and the related decryption method to decrypt (or decipher) the message.

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Public key or Asymmetric Cryptography

Use public key to determine a

private key.

Use public key to determine a

private key.

use sender’s public key to

encrypt a message

use sender’s public key to

encrypt a message

Sender generates a public key

Sender generates a public key


Send public key

use private key to decrypt this message

use private key to decrypt this message

sendersender receiverreceiver

No-one without access to Sender’s private No-one without access to Sender’s private key (or the information used to construct it) key (or the information used to construct it)

can easily decrypt the message!!can easily decrypt the message!!

No-one without access to Sender’s private No-one without access to Sender’s private key (or the information used to construct it) key (or the information used to construct it)

can easily decrypt the message!!can easily decrypt the message!!

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Hash Function Algorithms

• A hash function is a math equation that create a message digest from message.

• A message digest is used to create a unique digital signature from a particular document.

• MD5 example

Hash Function

Original Message(Document, E-mail)

Digest

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digital signature


receiverreceiver

sendersender

Public keyPublic key

Private keyPrivate key

Decrypt messageDecrypt message

How can Receiver determine that How can Receiver determine that the message received was indeed the message received was indeed

sent by Sender?sent by Sender?

How can Receiver determine that How can Receiver determine that the message received was indeed the message received was indeed

sent by Sender?sent by Sender?

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digital signatureData

Hash

VerifySignature

Public Key

?

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Man in MiddleMan in Middle

receiverreceiversendersender

Modify Modify

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Digital certificate

• A digital certificate (DC) is a digital file that certifies the identity of an individual or institution, or even a router seeking access to computer- based information. It is issued by a Certification Authority (CA), and serves the same purpose as a driver’s license or a passport

http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci213831,00.html

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Digital certificate

CERTIFICATE

IssuerIssuer

SubjectSubject

Issuer DigitalIssuer DigitalSignatureSignature

Subject Public Subject Public KeyKey

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Certification Authorities

• A trusted agent who certifies public keys for general use (Corporation or Bank).– User has to decide which CAs can be trusted.

• The model for key certification based on friends and friends of friends is called “Web of Trust”.– The public key is passing from friend to friend.– Works well in small or high connected worlds.– What if you receive a public key from someone you don’t

know?

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CA model

Root Certificate

CA Certificate

Browser Cert.

CA Certificate

Server Cert.

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What is the Process of obtaining a certificate

CA

Sender Receiver

generates a public/private

key pair

generates a public/private

key pair

Verify sender’s identity and issues digital certificate

containing the public key

Verify sender’s identity and issues digital certificate

containing the public key

Privatekey

Publickey

EncryptEncrypt Verify and Decrypt

Verify and Decrypt

CertificateCertificate

OK!!OK!!

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Secure Sockets Layer

• Secure Sockets Layer (SSL) is used to validate the identities of two computers involved in a connection across a public network, and to ensure that the data sent between the two computers is encrypted

• SSL uses digital certificates and public and digital certificates and public and privateprivate keyskeys

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Secure Sockets Layer

Application

SSL

TCP

IP

Application

SSL

TCP

IPIP

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Advantages of SSL

• Independent of application layer• Includes support for negotiated encryption

techniques.– easy to add new techniques.

• Possible to switch encryption algorithms in the middle of a session

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HTTPS Usage

• HTTPS is HTTP running over SSL.– used for most secure web transactions.– HTTPS server usually runs on port 443.– Include notion of verification of server via a

certificate.– Central trusted source of certificates

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SSL and ISA server 2006

• SSL bridging

SSL tunneling

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Configuring SSL-to-SSL Bridging for Secured Websites

• Working with Third-Party Certificate Authorities

• Installing a Local Certificate Authority and Using Certificates

• Modifying a Rule to Allow for End-to-End SSL Bridging

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• Installing an SSL Certificate on a SharePoint Server

• Exporting and Importing the SharePoint SSL Certificate to the ISA Server

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• Creating a SharePoint Publishing Rule

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• Choosing a certificate for the listener

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Configuring Server Publishing Rule

Configuring Access to Internal Resources

Documents

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