Cisco DPC3925 Router Manual PDF (Setup & Configuration Guide)

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4021192 Rev B

Configure Security

Security > VPN Passthrough

Use this page to configure Virtual Private Network (VPN) support. Enabling the

settings on this page allows VPN tunnels using IPsec or PPTP protocols to pass

through the gateway's firewall. Select the

VPN Passthrough

tab to open the Security

VPN Passthrough page.

Use the descriptions and instructions in the following table to configure the VPN

passthrough for your residential gateway. After you make your selections, click

Save

Settings

to apply your changes or

Cancel Changes

to cancel.

Section

Field Description

VPN

Passthrough

IPSec Passthrough

Enables/disables Internet Protocol Security (IPsec). IPsec is a suite of

protocols used to implement secure exchange of packets at the IP layer. If

you enable IPSec Passthrough, applications that use IPsec (IP Security) can

pass through the firewall. To disable IPSec Passthrough select

Disable

.

Select the desired option:



Enable

(factory default)



Disable

PPTP Passthrough

Enables/disables Point-to-Point Tunneling Protocol (PPTP). PPTP allows the

Point-to-Point Protocol (PPP) to be tunneled through an IP network. If you

enable PPTP passthrough, applications that use Point to Point Tunneling

Protocol (PPTP) can pass through the firewall To disable PPTP Passthrough

select

Disable

.

Select the desired option:



Enable

(factory default)



Disable

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4021192 Rev B

57

Configure Security

Security > VPN

A Virtual Private Network (VPN) is a connection between two endpoints in different

networks that allows private data to be sent securely over public networks or other

private networks. This is accomplished by creating a "VPN tunnel." A VPN tunnel

connects the two PCs or networks and allows data to be transmitted over the

Internet as if it were on a private network. The VPN tunnel uses IPsec to encrypt the

data sent between the two endpoints and encapsulate the data within a normal

Ethernet/IP frame allowing the data to pass between networks securely and

seamlessly.

A VPN provides a cost-effective and more secure alternative to using a private,

dedicated, leased line for a private network. Using industry standard encryption and

authentication techniques, an IPsec VPN creates a secure connection that operates as

if you were directly connected to your local private network.

For example, a VPN allows users to sit at home and connect to his/her employer's

corporate network and receive an IP address in their private network just as though

they were sitting in their office connected to their corporate LAN.

Select the

VPN

tab to open the Security VPN page.

Use this page to configure the VPN for your residential gateway.

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4021192 Rev B

Configure Security

Security VPN Tunnel Page Description

Use the descriptions and instructions in the following table to configure the VPN

tunnel for your gateway. After you make your selections, click

Save Settings

to

apply your changes or

Cancel Changes

to cancel.

Section

Field Description

VPN Tunnel

Select Tunnel Entry

Allows you to display a list of created VPN tunnels

Create Button

Click this button to create a new tunnel entry

Delete Button

Click this button to delete all settings for the selected tunnel

Summary Button

Click this button to display the settings and status of all enabled tunnels

IPSec VPN Tunnel

Allows you to enable or disable Internet Security Protocol for the VPN tunnel

Tunnel Name

Enter the name for this tunnel

Local Secure

Group

Select the local LAN user(s) that can use this VPN tunnel. This may be a single IP

address or sub-network. Note that the Local Secure Group must match the remote

gateway's Remote Secure Group.

IP

Enter the IP address of the local network

Mask

If the Subnet option is selected, enter the mask to determine the IP address on the

local network

Remote

Secure

Group

Select the remote LAN user(s) behind the remote gateway who can use this VPN

tunnel. This may be a single IP address, a sub-network, or any addresses. If "Any"

is set, the Gateway acts as responder and accepts requests from any remote user.

Note that the Remote Secure Group must match the remote gateway's Local Secure

Group.

IP

Enter the IP address of the remote network

Mask

If the Subnet option is selected, enter the mask to determine the IP addresses on

the remote network

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59

Configure Security

Section

Field Description

Remote

Secure

Gateway

Select the desired option,

IP Addr.

,

Any

, or

FQDN

. If the remote gateway has a

dynamic IP address, select

Any

or

FQDN

. If

Any

is selected, then the Gateway will

accept requests from any IP address.

FQDN

If

FQDN

is selected, enter the domain name of the remote gateway, so the

Gateway can locate a current IP address using DDNS

IP

The IP address in this field must match the public (WAN or Internet) IP address of

the remote gateway at the other end of this tunnel

Key

Management

Key Exchange Method

The gateway supports both automatic and manual key management. When

automatic key management is selected, Internet Key Exchange (IKE) protocols are

used to negotiate key material for Security Association (SA). If manual key

management is selected, no key negotiation is needed. Basically, manual key

management is used in small static environments or for troubleshooting purposes.

Note that both sides must use the same key management method.

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Configure Security

Section

Field Description

Key

Management

(continued)

Select one of the following options for the key exchange method:



Auto (IKE)

–

Encryption:

The Encryption method determines the length of the key used

to encrypt/decrypt ESP packets. Notice that both sides must use the same

method.

–

Authentication:

The Authentication method authenticates the

Encapsulating Security Payload (ESP) packets. Select

MD5

or

SHA

. Notice

that both sides (VPN endpoints) must use the same method.



MD5: A one-way hashing algorithm that produces a 128-bit digest



SHA: A one-way hashing algorithm that produces a 160-bit digest

–

Perfect Forward Secrecy (PFS)

: If PFS is enabled, IKE Phase 2 negotiation

will generate new key material for IP traffic encryption and authentication.

Note that both sides must have PFS enabled.

–

Pre-Shared Key:

IKE uses the Pre-Shared Key to authenticate the remote

IKE peer. Both character and hexadecimal values are acceptable in this

field, e.g., "My_@123" or "0x4d795f40313233". Note that both sides must use

the same Pre-Shared Key.

–

Key Lifetime:

This field specifies the lifetime of the IKE generated key. If

the time expires, a new key will be renegotiated automatically. The Key

Lifetime may range from 300 to 100,000,000 seconds. The default lifetime is

3600

seconds.



Manual

–

Encryption:

The Encryption method determines the length of the key used

to encrypt/decrypt ESP packets. Notice that both sides must use the same

method.

–

Encryption Key:

This field specifies a key used to encrypt and decrypt IP

traffic. Both character and hexadecimal values are acceptable in this field.

Note that both sides must use the same Encryption Key.

–

Authentication:

The Authentication method authenticates the

Encapsulating Security Payload (ESP) packets. Select MD5 or SHA. Notice

that both sides (VPN endpoints) must use the same method.



MD5: A one-way hashing algorithm that produces a 128-bit digest



SHA: A one-way hashing algorithm that produces a 160-bit digest

–

Authentication Key:

This field specifies a key used to authenticate IP

traffic. Both character and hexadecimal values are acceptable in this field.

Note that both sides must use the same Authentication Key.

–

Inbound SPI/Outbound SPI:

The Security Parameter Index (SPI) is carried

in the ESP header. This enables the receiver to select the SA, under which a

packet should be processed. The SPI is a 32-bit value. Both decimal and

hexadecimal values are acceptable. e.g., "987654321" or "0x3ade68b1". Each

tunnel must have a unique Inbound SPI and Outbound SPI. No two tunnels

share the same SPI. Note that the Inbound SPI must match the remote

gateway's Outbound SPI, and vice versa.

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