GigaSMART Passive TLS/SSL Decryption

TLS/SSL encryption secures traffic between a client and a server, such as a Web server. TLS/SSL decryption uses keys to decode the traffic between the client and server.

SSL and Transport Layer Security (TLS) protocols consist of a set of messages exchanged between a client and server to set up and tear down the TLS/SSL connection between them. To set up the connection, the client and server use the Public Key Infrastructure (PKI) to exchange the bulk encryption keys needed for data transfer.

1 shows the basic TLS/SSL handshake between a client and server to establish a session. The messages are unencrypted up to step 6 in 1. The messages are encrypted after step 6, including the step 9 Finished message.

 

1

Basic TLS/SSL Handshake

Once a session has been established, the keys are saved so a session can be resumed efficiently later. 2 shows the resumed TLS/SSL handshake, with fewer steps.

2

Resumed TLS/SSL Handshake

Passive TLS/SSL decryption can be deployed close to the server, as shown in 3.

3

Inbound (Server Side)

Passive TLS/SSL decryption can also be deployed close to an TLS/SSL proxy, with the server in the Enterprise domain as shown in 4.

4

Outbound (Client/Enterprise Side)

In 3, tap traffic to the server and then send it for decryption. In 4, tap traffic to the proxy and then send it for decryption. You can have a deployment with either a server or a proxy, but not both.

The supported protocols are as follows:

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SSL 3.0

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TLS 1.0

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TLS 1.1

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TLS 1.2

The supported authentication (Au) is as follows:

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RSA

The supported key exchange (Kx) is as follows:

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RSA

The supported encryption algorithms (Enc) are as follows:

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NULL

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RC4

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DES

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3DES

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AES (including GCM mode)

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CAMELLIA

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SEED

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IDEA

The supported compression algorithm is as follows:

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NULL

The supported digest algorithms are as follows:

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MD5

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SHA1

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SHA2

The supported key sizes are 128, 256, 512, 1024, 2048, and 4096.

The supported TLS extensions are as follows:

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Extended Master Secret, RFC 7627

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Encrypt-then-MAC, RFC 7366

The supported ciphers are listed in Table 5: Supported Ciphers for Passive SSL decryption.

Table 5: Supported Ciphers for Passive SSL decryption

Cipher Name	Kx	Au	Enc	Bits	Mac
TLS_RSA_WITH_NULL_MD5	RSA	RSA	NULL	0	MD5
TLS_RSA_WITH_NULL_SHA	RSA	RSA	NULL	0	SHA
TLS_RSA_EXPORT_WITH_RC4_40_MD5	RSA_EXPORT	RSA_EXPORT	RC4_40	40	MD5
TLS_RSA_WITH_RC4_128_MD5	RSA	RSA	RC4_128	128	MD5
TLS_RSA_WITH_RC4_128_SHA	RSA	RSA	RC4_128	128	SHA
TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5	RSA_EXPORT	RSA_EXPORT	RC2_CBC_40	40	MD5
TLS_RSA_WITH_IDEA_CBC_SHA	RSA	RSA	IDEA_CBC	128	SHA
TLS_RSA_EXPORT_WITH_DES40_CBC_SHA	RSA_EXPORT	RSA_EXPORT	DES40_CBC	40	SHA
TLS_RSA_WITH_DES_CBC_SHA	RSA	RSA	DES_CBC	56	SHA
TLS_RSA_WITH_3DES_EDE_CBC_SHA	RSA	RSA	3DES_EDE_CBC	168	SHA
TLS_RSA_WITH_AES_128_CBC_SHA	RSA	RSA	AES_128_CBC	128	SHA
TLS_RSA_WITH_AES_256_CBC_SHA	RSA	RSA	AES_256_CBC	256	SHA
TLS_RSA_WITH_CAMELLIA_128_CBC_SHA	RSA	RSA	CAMELLIA_128_CBC	128	SHA
TLS_RSA_WITH_CAMELLIA_256_CBC_SHA	RSA	RSA	CAMELLIA_256_CBC	256	SHA
TLS_RSA_WITH_SEED_CBC_SHA	RSA	RSA	SEED_CBC	128	SHA
TLS_RSA_WITH_NULL_SHA256	RSA	RSA	NULL	0	SHA256
TLS_RSA_WITH_AES_128_CBC_SHA256	RSA	RSA	AES_128_CBC	128	SHA256
TLS_RSA_WITH_AES_256_CBC_SHA256	RSA	RSA	AES_256_CBC	256	SHA256
TLS_RSA_WITH_AES_128_GCM_SHA256	RSA	RSA	AES_128_GCM	128	SHA256
TLS_RSA_WITH_AES_256_GCM_SHA384	RSA	RSA	AES_256_GCM	256	SHA384

All algorithms used for Passive TLS/SSL decryption are FIPS 140-2 compliant.

All key URLs must point to an RSA private key stored in the PEM or PKCS12 format, as follows:

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http://keyserver.domain.com/path/keyfile.pem

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https://keyserver.domain.com/path/keyfile.pem

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ftp://keyserver.domain.com/path/keyfile.pem

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tftp://keyserver.domain.com/path/keyfile.pem

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scp://username[:password]@keyserver.domain.com/path/keyfile.pem

The supported applications are as follows:

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HTTPS

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FTPS

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SMTP, IMAP, and POP3 with StartTLS

The limitations of Passive TLS/SSL decryption are as follows:

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Only IPv4

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Only regular maps; no virtual ports (vports)

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Only combined with the de-duplication GigaSMART operation

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Only one private key per PKCS12 file

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Only server-side authentication

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Only the protocols and ciphers listed in Supported Protocols, Algorithms, and CiphersS.

Note:  If an TLS/SSL session cannot be decrypted due to having a non-supported protocol or cipher and if the GS Parameter SSL Decryption has Decrypt Fail Action is set to Pass to Tool Port, the packets will be forwarded to the tool without decryption . Non-supported ciphers and protocols include SSL 2.0, Diffie-Hellman (DHE keys), Ephemeral keys, Elliptic Curves Extension, compression, and 8K key size.

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GigaSMART card may require reboot after configuring and unconfiguring DSSL apps multiple times without reload to prevent memory failure. For more information, refer to Reload a GigaSMART Line Card or Module.

The GigaSMART license for Passive TLS/SSL decryption is installed as any other license.

There are no limits to the number of Passive TLS/SSL decryption sessions or the number of users.

To perform the configuration in the following section, you must have an admin level access role.

Before uploading keys or configuring TLS/SSL, you must create an SSL keychain password. The password is used to encrypt the private keys that you upload to the node.

Keychain passwords are not saved on the node. Refer to Notes about Private Keys and Passwords.

Note:  When uploading TLS/SSL keys, make sure that you are not creating a duplicate key. Adding a duplicate key can cause errors.

To create an TLS/SSL keychain password, use the following steps:

1. On the left navigation pane, click , and then select Physical > Nodes.

2. In the Physical Nodes page, select the node for which you want to create the Key Store password.

3. Go to GigaSMART>Passive SSL >Key Store.

4. Click Keychain Password.

5. Enter a password in the Password and Confirm Password fields.

   You can only configure a strong password. A strong password should include at least eight (8) or more characters (up to 64) and include the following:

   o

   one uppercase letter

   o

   one lowercase letter

   o

   one numerical character

   o

   one special character

6. Enable the Auto login check box to let GigaVUE-FM unlock the key store when the node reboots.

7. Click Submit.

After keys are installed on the node, you will be prompted to enter the password after any login as well as after a node reboot, for example:

If you are a user who does not have an admin level access role, when you enter the configure terminal mode, the following message is displayed:

Password required. Please contact administrator.

If you are a user with an admin level access role, but you enter an incorrect password, the following message is displayed:

Password does not match. Please reenter the password

If an TLS/SSL keychain password is lost, it can be reset, but all existing private keys will be revoked. When there are keys installed on the node, a warning is displayed before you are prompted for the new password.

Once you have a new password, you will have to upload the keys again.

This section describes working with private keys as well as services. Keys must be uploaded to the GigaVUE H Series node using a unique alias. Services must be defined for each server destination that needs decryption. There are two types of decryption. If the service is associated with a certificate then it is called service based decryption. If only certificate is added to the node without creating service then it is key certificate based decryption.

To perform the configuration in the following section, you must have an admin level access role.

Encrypted private keys are saved on the node. Refer to Notes about Private Keys and Passwords.

Note:  When uploading TLS/SSL keys, make sure that you are not creating a duplicate key. Adding a duplicate key can cause errors.

After you have uploaded a private key, you can add a service. A service maps to a physical server, such as an HTTP server. One server can run multiple services. A service is a combination of an IP address and a server port number. Also, the key and the service must be tied together.

Prerequisites

Before creating a service, you must do the following:

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Upload a private key as described in Upload TLS/SSL Private Keys

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Create GigaSMART Group with TLS/SSL Decryption enabled.

To create a service, do the following:

1.

From the device view, select GigaSMART > Passive SSL > SSL Services. The SSL Services page appears.

2.

Click New.

3.

On the SSL Service configuration page, do the following:

o

Enter an alias.

o

Click on the Default Service (inbuilt key will be used for decryption for any service) check box to allow GigaVUE‑FM to enable default service.

Note:  When opting for the Default service along with service based decryption, other than the particular service that is opted for service based, other connections will be decrypted using the key available on the default service.

o

Enter the information for the service: IP Address, Server Port.

o

Select the alias of SSL Key previously uploaded. For the steps, refer to Upload TLS/SSL Private Keys.

o

Select the GigaSMART Group with TLS/SSL decryption enabled to associate with this TLS/SSL service.

4.

Click Apply.

Delete TLS/SSL Service

To delete a particular TLS/SSL service select the service on the TLS/SSL Services page, and then select Delete. To delete all TLS/SSL services, select multiple keys.

Notes about Private Keys and Passwords

Consider the following notes about private keys and passwords:

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Encrypted private keys are stored on the node. When a private key is uploaded, it is encrypted with a password before it is stored, therefore keys are password-protected. Keychain passwords are not stored on the node.

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Because only encrypted private keys are stored on the node and because the keychain password is not stored on the node, after any node reboot you will be prompted to enter the password. Until the password is entered, Passive TLS/SSL decryption is not working.

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Key content cannot be displayed.

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Keys that are synchronized across a cluster are encrypted.

Use the following table of ECODE messages to assist with troubleshooting Passive TLS/SSL decryption:

ECODE	Description
81	TCP flow errors detected. Make sure you see the complete TCP flow. Use the de-duplication GigaSMART operation with Passive TLS/SSL decryption.
103	Session limit reached. The session table has been exhausted. If the session timeout (session-timeout) value is large, lower it.
104	Key/ticket cache limit reached. The allocated cache entries have been used up. If the timeout (key-cache-timeout or ticket-cache-timeout) value is large, lower it.
206	No server info. A flow has been received for which service-key mapping is not defined.
213	Packets for missed TCP handshake. Packets were received for TCP flows that do not exist. If the device was just started, this should trend down quickly.
218	Unknown TLS/SSL version. An TLS/SSL handshake processing error occurred. Use the de-duplication GigaSMART operation with Passive TLS/SSL decryption.
221	Unknown TLS/SSL version. An unsupported TLS/SSLv2 handshake was seen.
222	Protocol error. An unsupported protocol version was seen.
225	Unsupported cipher. The cipher suite cannot be decrypted.
226	Pre-master secret error. Check that the private key is correct and that the session is complete.
228	Generic decryption error. Usually indicates errors in the handshake. Check that you are getting the full session from both sides.
231	Invalid MAC. Likely indicates that invalid or truncated packets have been received.
232	Session not in cache. Indicates that you are trying to decrypt a restarted session where the original negotiation was not seen. These should trend down in time, but if they do not, increase the key-cache-timeout value.
237	Cannot decrypt ephemeral key based encryption. One of the Ephemeral/PFS ciphersuites, usually Diffie-Hellman Ephemeral, has been seen. These are not supported.
245	Ticket not in cache. This is usually not an error. Indicates that you are trying to decrypt a restarted session where the original negotiation was not seen. These should trend down in time, but if they do not, increase the ticket-cache-timeout value.

GigaSMART provides support for Flow Ops reporting. You can generate the Flow Ops report for Passive TLS/SSL Decryption, view the session summary and session statistics, and export the report to a remote server.

To view the session summary and session details of the Passive TLS/SSL Decryption Flow Ops report:

1. From the device view, go to System > GigaSMART > Passive SSL > Session Statistics.

2. From the GigaSMART Group drop-down list, select the required GigaSMART group. The Session Summary and Session Details appear. For descriptions of the session statistics, refer to Flow Ops Report Statistics for Passive TLS/SSL Decryption.

3. In the Session Summary table, click the Report Summary link to view the graphical representation of the trending data for the Passive SSL Decryption session summary as shown in the following figures:

 

You can also choose to export the session summary to a remote server. Select the required row in the Session Summary table, and then click Export Report. The Upload Flow Ops Report page appears. Enter the remote server path and password to access the server. Click Upload. The details are exported to the remote server.

The following sections provide examples and commands (CLI) of TLS/SSL decryption. Refer to the following:

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Example 1: TLS/SSL Decryption with a Regular Map

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Example 2: TLS/SSL Decryption with De-duplication

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Other Usage Examples