VPN

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Summary

VPN (Virtual Private Network) is a method for secure data transfer through unsafe public networks. This page is an overview of different types of VPN that can be used with RUT routers.

OpenVPN

The default OpenVPN Configuration list is empty, so you have to define your own configuration to establish any sort of OpenVPN connection. OpenVPN configurations can have one of two roles: client or server. Let’s start with an OpenVPN client. To create it, enter the desired instance name in the New configuration name field, select the instance’s role from the Role list and press the Add New button.

Once you’ve added a new OpenVPN instance there is no need to press the Save button, since the Add New button both creates and saves the new instance. By default the instance will be disabled and unconfigured. In order to establish an OpenVPN connection you must Enable your instance, enter an OpenVPN server address, choose an authentication method and a few other things, all of which can be configured in the Settings window, which can reached by pressing the Edit button next to your OpenVPN instance (as shown in the figure above).

OpenVPN Client


This section is overview of OpenVPN Client configuration.

The figure above is an example of a configured OpenVPN Client instance that uses the UDP protocol and TLS/Password authentication. Comprehensible explanations on how to configure each field are presented in the table below.

Field name Value Description
Enable yes | no; Default: no Enables the OpenVPN instance
TUN/TAP TUN (tunnel) | TAP (bridged); Default: TUN (tunnel) OpenVPN interface type. TUN is most often in typical VPN connections, however, TAP is required in some Ethernet bridging configurations
Protocol UDP | TCP; Default: UDP The transfer protocol used by the OpenVPN connection. TCP is connection oriented – once a connection is established, data can be sent bidirectionally. UDP is a simpler, connectionless Internet protocol. UDP is usually faster but TCP has more security features. Choose the connection protocol according to your needs.
Port integer [0..65535]; Default: 1194 TCP/UDP Port number for both local and remote endpoints (make sure that the chosen port is allowed by firewall)
LZO yes | no; Default: no With LZO compression, your VPN connection will generate less network traffic. However, enabling this causes a higher CPU load. Use it carefully with a high traffic rate or low CPU resources
Encryption DES-CBC 64 | RC2-CBC 128 | DES-EDE-CBC 128 | DES-EDE3-CBC 192 | DESX-CBC 192 | BF-CBC 128 | RC2-40-CBC 40 | CAST5-CBC 128 | RC2-40CBC 40 | CAST5-CBC 128 | RC2-64-CBC 64| AES-128-CBC 128 | AES-192-CBC 192 | AES-256-CBC 256 | none; Default: BF-CBC 128 Packet encryption algorithm
Authentication TLS | Static Key | Password | TLS/Password; Default: TLS Authentication mode, used to secure data sessions.

Static key is a secret key used for server–client authentication.

TLS authentication mode uses X.509 type certificates:

Certificate Authority (CA), Client certificate, Client key.

All mentioned certificates can be generated using OpenVPN or Open SSL utilities on any type of host machine.

Password is a simple username/password based authentication where the owner of the OpenVPN server provides the login data.

TLS/Password uses both TLS and Password authentication

TLS cipher all | DHE+RSA | custom; Default: all Packet encryption algorithm cipher
Remote host / IP address ip; Default: " " IP address or hostname of an OpenVPN server
Resolve retry integer | infinite; Default: infinite Time in seconds to resolve server hostname periodically in case of first resolve failure before generating service exception
Keep alive integer *space* integer; Default: " " Defines two time intervals: one is used to periodically send ICMP request to the OpenVPN server, the other defines a time window, which is used to restart the OpenVPN service, if no ICMP response is received during the window time slice.

Example: 10 60

Remote network IP address ip; Default: " " LAN IP address of the remote network (server)
Remote network IP netmask ip; Default: " " LAN IP subnet mask of the remote network (server)
Username string; Default: " " User name used for authentication
Password string; Default: " " Password name used for authentication
Extra options string; Default: " " Extra options to be used by the OpenVPN instance
HMAC authentication algorithm none | SHA1 | SHA256 | SHA384 | SHA512; Default: SHA1 HMAC authentication algorithm type
Additional HMAC authentication yes | no; Default: no An additional layer of HMAC authentication on top of the TLS control channel to protect against DoS attacks
Certificate authority .ca file; Default: " " Certificate authority is an entity that issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate
Client certificate .crt file; Default: " " Client certificate is a type of digital certificate that is used by client systems to make authenticated requests to a remote server. Client certificates play a key role in many mutual authentication designs, providing strong assurances of a requester's identity
Client key .key file; Default: " " Authenticates the client to the server and establishes precisely who they are
Private key decryption password (optional) string; Default: " " Decrypts server private key password. Use only if server's .key file is encrypted with a password

After setting any of these parameters press the Save button or else the changes will not be applied. Some of the selected parameters will be shown in the configuration list table. You should also be aware of the fact that the router will launch a separate OpenVPN service for every configuration entry (if it is defined as active at the time, of course) so the router has the ability to act as server and client at the same time.

OpenVPN Server


This section is overview of OpenVPN Client configuration.

The figure above is an exampled of a configured OpenVPN Server instance that uses the UDP protocol and TLS authentication. As you can see, the configuration is similar to OpenVPN Client but with a few key differences. Comprehensible explanations on how to configure each field are presented in the table below.

Field name Value Description
Enable yes | no; Default: no Enables the OpenVPN instance
TUN/TAP TUN (tunnel) | TAP (bridged); Default: TUN (tunnel) OpenVPN interface type. TUN is most often in typical VPN connections, however, TAP is required in some Ethernet bridging configurations
Protocol UDP | TCP; Default: UDP The transfer protocol used by the OpenVPN connection. TCP is connection oriented – once a connection is established, data can be sent bidirectionally. UDP is a simpler, connectionless Internet protocol. UDP is usually faster but TCP has more security features. Choose the connection protocol according to your needs.
Port integer [0..65535]; Default: 1194 TCP/UDP Port number for both local and remote endpoints (make sure that the chosen port is allowed by firewall)
LZO yes | no; Default: no With LZO compression, your VPN connection will generate less network traffic. However, enabling this causes a higher CPU load. Use it carefully with a high traffic rate or low CPU resources
Encryption DES-CBC 64 | RC2-CBC 128 | DES-EDE-CBC 128 | DES-EDE3-CBC 192 | DESX-CBC 192 | BF-CBC 128 | RC2-40-CBC 40 | CAST5-CBC 128 | RC2-40CBC 40 | CAST5-CBC 128 | RC2-64-CBC 64| AES-128-CBC 128 | AES-192-CBC 192 | AES-256-CBC 256 | none; Default: BF-CBC 128 Packet encryption algorithm
Authentication TLS | Static Key | Password | TLS/Password; Default: TLS Authentication mode, used to secure data sessions.

Static key is a secret key used for server–client authentication.

TLS authentication mode uses X.509 type certificates:

Certificate Authority (CA), Client certificate, Client key.

All mentioned certificates can be generated using OpenVPN or Open SSL utilities on any type of host machine.

Password is a simple username/password based authentication where the owner of the OpenVPN server provides the login data.

TLS/Password uses both TLS and Password authentication

TLS cipher all | DHE+RSA | custom; Default: all Packet encryption algorithm cipher
Client to client yes | no; Default: no Enables client to client communication in the Virtual network. In order for Client to client to work, the TLS Clients section most be utilized
Keep alive integer *space* integer; Default: " " Defines two time intervals: one is used to periodically send ICMP request to the OpenVPN server, the other defines a time window, which is used to restart the OpenVPN service, if no ICMP response is received during the window time slice.

Example: 10 60

Virtual network IP address ip; Default: " " IP address of the Virtual network, e.g., 10.0.8.0
Virtual network IP netmask ip; Default: " " Subnet mask of the Virtual network
Push option string; Default: " " Push options are a way to “push” user defined routes to connecting clients’ routing tables. In the example above, the server will push the route of 192.168.1.0 network with the 255.255.255.0 netmask to connecting clients. Therefore, the client will be able to reach devices in the 192.168.1.0 network. This is useful when a client needs to reach devices located in the OpenVPN server’s LAN.
Allow duplicate certificates yes | no; Default: no If checked, the server allows clients to connect with identical certificates
Certificate authority .ca file; Default: " " Certificate authority is an entity that issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate
Server certificate .crt file; Default: " " Server certificate is a type of digital certificate that is used to identify the OpenVPN server
Server key .key file; Default: " " Authenticates clients to the server
Diffie Hellman parameters .pem file; Default: " " DH parameters define how OpenSSL performs the Diffie-Hellman (DH) key-exchange.

TLS Clients


TLS Clients is a way to more specifically differentiate clients by their Common Name (CN) found in the client certificate file. It can be used to assign specific VPN addresses to specific clients and bind them to their LAN addresses so that other device‘s in the client‘s LAN can be reached from the server or other clients.

The TLS Clients section can be found in the OpenVPN Server configuration window, provided that the OpenVPN server uses TLS or TLS/Password authentication methods. To create a new TLS client, type in the new client‘s name in the text field found bellow the TLS Clients tab and press the Add button.

Field name Value Description
VPN instance name string; Default: " " With what VPN instance should the TLS Client be associated with
Endpoint name string; Default: " " Your endpoint name
Common name (CN) string; Default: " " Client’s Common Name (CN) found in the client’s certificate file
Virtual local endpoint ip; Default: " " Client’s virtual local address in the virtual network
Virtual remote endpoint ip; Default: " " Client’s virtual remote address in the virtual network
Private network ip; Default: " " Client’s private network (LAN) IP address
Private netmask ip; Default: " " Client’s private network (LAN) IP netmask

IPsec

The IPsec protocol client enables the router to establish a secure connection to an IPsec peer via the Internet. IPsec is supported in two modes - transport and tunnel. Transport mode creates a secure point to point channel between two hosts. Tunnel mode can be used to build a secure connection between two remote LANs serving as a VPN solution.

IPsec system maintains two databases: Security Policy Database (SPD) which defines whether to apply IPsec to a packet or not and specify which/how IPsec-SA is applied and Security Association Database (SAD), which contains a Key of each IPsec-SA.

The establishment of the Security Association (IPsec-SA) between two peers is needed for IPsec communication. It can be done by using manual or automated configuration.

Note: the router starts establishing a tunnel when data is sent from the router to a remote site over the tunnel. The Keep Alive feature is used for automatic tunnel establishment.

To create a new IPsec instance, go to the IPsec tab, type in a name for your new instance in the text field below the IPsec tab and press the Add button next to it.

Note: You can create a maximum of 5 IPsec instances.


Field name Value Description
Enable yes | no; Default: no Toggles the IPsec instance ON or OFF
IKE version IKEv1 | IKEv2; Default: IKEv1 Method of key exchange
Mode Main | Aggressive; Default: Main ISAKMP phase 1 exchange mode
Type Tunnel | Transport; Default: Tunnel Type of connection
My identifier type Address | FQDN | User FQDN; Default: FQDN Type of connection
My identifier string; Default: " " In case RUT has a Private IP, its identifier should be its own LAN network address. In this way, the Road Warrior approach is possible
Local IP address/Subnet mask ip/netmask | Default: " " Local network secure group IP address and mask used to determine at what subnet an IP address can be accessed. Netmask range [0 - 32]. If left empty IP address will be selected automatically
Left firewall yes | no; Default: yes Excludes IPsec tunnel from firewall rules
Force encapsulation yes | no; Default: no Forces UDP encapsulation for ESP packets even if no NAT situation is detected
Dead Peer Detection yes | no; Default: no The values 'clear', 'hold' and 'restart' all activate DPD
Pre-shared key string; Default: " " A shared password used for authentication between the peers
Remote VPN endpoint host | ip; Default: " " IP address or hostname of the remote IPsec instance
Remote IP address/subnet mask ip/integer [0..32]; Default: " " Remote network secure group IP address and mask used to determine to what subnet an IP address belongs to. Should differ from device’s LAN IP
Right firewall yes | no; Default: yes Excludes remote side IPsec tunnel from firewall rules
Enable keep alive yes | no; Default: no Toggles the tunnel's keep alive function ON or OFF
Host host | ip; Default: " " A host address to which an ICMP echo requests will be sent for keep alive purposes
Ping period (sec) integer [0..9999999]; Default: " " Send ICMP echo request every x seconds (x being the number specified in this field)
Allow WebUI access yes | no; Default: no If enabled, allows router's WebUI access through the IPsec tunnel

Phase 1/Phase 2


Phase 1 and Phase 2 must be configured in accordance with the IPSec server configuration, thus algorithms, authentication and lifetimes of each phase must be identical.


Field name Value Description
Encryption algorithm DES | 3DES | AES 128 | AES 192 | AES256; Default: 3DES The encryption algorithm must match with another incoming connection
Authentication MD5 | SHA1 | SHA256 | SHA384 | SHA512; Default: SHA1 The authentication algorithm must match with another incoming connection
Has algorithm MD5 | SHA1 | SHA256 | SHA384 | SHA512; Default: SHA1 The hash algorithm must match with another incoming connection
DH group MODP768 | MODP1024 | MODP1536 | MODP2048 | MODP3072 | MODP4096; Default: MODP1536 The DH (Diffie-Helman) group must match with another incoming connection
PFS group MODP768 | MODP1024 | MODP1536 | MODP2048 | MODP3072 | MODP4096 | No PFS; Default: MODP1536 The PFS (Perfect Forward Secrecy) group must match with another incoming connection
Lifetime time; Default: 8 hours Duration for the phase

GRE Tunnel

GRE (Generic Routing Encapsulation RFC2784) is a solution for tunneling RFC1812 private address-space traffic over an intermediate TCP/IP network such as the Internet. GRE tunneling does not use encryption it simply encapsulates data and sends it over the WAN.


In the example network diagram two distant networks LAN1 and LAN2 are connected. To create GRE tunnel the user must know the following parameters:

1. Source and destination IP addresses

2. Tunnel’s local IP address

3. Distant network’s IP address and Subnet mask

To create a new GRE instance, go to the GRE Tunnel tab, type in a name for your new instance in the text field below the GRE Tunnel tab and press the Add New button next to it. The newly created instance will be disabled and unconfigured. To configure it press the Edit button located next to it. This action will redirect you to the instance’s GRE Tunnel Configuration window.


Field name Value Description
Enabled yes | no; Default: no Toggles GRE Tunnel ON or OFF
Remote endpoint IP address host | ip; Default: " " Specifies remote WAN IP address or hostname
Remote network ip; Default: " " LAN IP address of the remote device
Remote network netmask integer [0..32]; Default: " " LAN netmask of the remote device
Local tunnel IP ip; Default: " " Local virtual IP address. Can’t be in the same subnet as LAN network
MTU integer [0..1500]; Default: 1476 The maximum transmission unit in bytes
TTL integer [0..255]; Default: 255 Fixed time-to-live (TTL) value on tunneled packets. The 0 is a special value meaning that packets inherit the TTL value
PMTUD yes | no; Default: no Toggles the Path Maximum Transmission Unit Discovery (PMTUD) status on this tunnel ON or OFF
Redirect LAN to GRE yes | no; Default: no Redirects LAN traffic to the GRE interface
Enable Keep alive yes | no; Default: no Gives the ability for one side to originate and receive keep alive packets to and from a remote router
Keep Alive host host | ip; Default: " " Keep Alive IP address to send pings to. Preferably this should be an IP address which belongs to the LAN network on the remote device
Keep alive interval integer [0..255]; Default: " " Frequency at which ICMP packets are sent by the Keep Alive function (in seconds)

PPTP

Point-to-Point Tunneling Protocol (PPTP) is a protocol (set of communication rules) that allows corporations to extend their own corporate network through private "tunnels" over the public Internet. Effectively, a corporation uses a wide-area network as a single large local area network. A company no longer needs to lease its own lines for wide-area communication but can securely use the public networks.

PPTP Client


To create a new PPTP instance, go to the PPTP tab, select the Role (server or client) of your instance, type in a name in the New configuration name field and press the Add button next to it. The newly created instance will be disabled and unconfigured. To configure it click the Edit button located next to it. This action will redirect you to the instance’s PPTP Configuration window.


Field name Value Description
Enable yes | no; Default: no Toggles PPTP Client ON or OFF
Use as default gateway yes | no; Default: no Use this PPTP instance as default gateway
Client to client yes | no; Default: no Toggles client to client on the PPTP tunnel ON or OFF
Server host | ip; Default: " " PPTP server's IP address or hostname
Username string; Default: " " User name for authorization with the server
Password string; Default: " " Password used for authorization with the server

PPTP Server


Field name Value Description
Enable yes | no; Default: no Toggles PPTP Server ON or OFF
Local IP ip; Default: 192.168.0.1 Virtual IP Address of this PPTP server
Remote IP range begin ip; Default: 192.168.0.20 Client IP address leases beginning
Remote IP range end ip; Default: 192.168.0.30 Client IP address leases end
User name string; Default: youruser Client's user name used for authentication with this server
Password string; Default: yourpass Client's password used for authentication with this server
PPTP Client's IP ip; Default: " " Client’s IP address. Leave empty to assign a random IP from the IP range specified above

L2TP

In computer networking, Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs). It is more secure than PPTP but, because it encapsulates the transferred date twice, but it is slower and uses more CPU power.

L2TP Client


To create a new L2TP instance, go to the L2TP tab, select the Role (server or client) of your instance, type in a name in the New configuration name field and press the Add button next to it. The newly created instance will be disabled and unconfigured. To configure it press the Edit button located next to it. This action will redirect you to the instance’s L2TP Configuration window.


Field name Value Description
Enable yes | no; Default: no Toggles L2TP Client ON or OFF
Server host | ip; Default: " " L2TP server's remote IP address or hostname
Username string; Default: " " User name used to authenticate you to the L2TP server
Password string; Default: " " Password used to authenticate you to the server

L2TP Server


Field name Value Description
Enable yes | no; Default: no Toggles L2TP Server ON or OFF
Local IP ip; Default: 192.168.0.1 Virtual IP Address of this L2TP server
Remote IP range begin ip; Default: 192.168.0.20 Client IP address leases beginning
Remote IP range end ip; Default: 192.168.0.30 Client IP address leases end
User name string; Default: user Client's user name used for authentication with this server
Password string; Default: pass Client's password used for authentication with this server