Administrator Guide

IPsec is a set of protocols developed by the internet engineering task force (IETF) to support secure exchange of packets at the
IP layer. IPsec supports two encryption modes: transport and tunnel.
● Transport mode — encrypts only the data portion (payload) of each packet, but leaves the header untouched.
● Tunnel mode — is more secure and encrypts both the header and payload. On the receiving side, an IPsec-compliant device
decrypts each packet.
NOTE: Dell EMC Networking OS supports only Transport Encryption mode in OSPFv3 authentication with IPsec.
With IPsec-based authentication, Crypto images are used to include the IPsec secure socket application programming interface
(API) required for use with OSPFv3.
To ensure integrity, data origin authentication, detection and rejection of replays, and confidentiality of the packet, RFC 4302
and RFC 4303 propose using two security protocols — authentication header (AH) and encapsulating security payload (ESP).
For OSPFv3, these two IPsec protocols provide interoperable, high-quality cryptographically-based security.
● HA — IPsec authentication header is used in packet authentication to verify that data is not altered during transmission and
ensures that users are communicating with the intended individual or organization. Insert the authentication header after the
IP header with a value of 51. AH provides integrity and validation of data origin by authenticating every OSPFv3 packet. For
detailed information about the IP AH protocol, refer to RFC 4302.
● ESP — encapsulating security payload encapsulates data, enabling the protection of data that follows in the datagram. ESP
provides authentication and confidentiality of every packet. The ESP extension header is designed to provide a combination
of security services for both IPv4 and IPv6. Insert the ESP header after the IP header and before the next layer protocol
header in Transport mode. It is possible to insert the ESP header between the next layer protocol header and encapsulated
IP header in Tunnel mode. However, Tunnel mode is not supported in Dell EMC Networking OS. For detailed information
about the IP ESP protocol, refer to RFC 4303.
In OSPFv3 communication, IPsec provides security services between a pair of communicating hosts or security gateways using
either AH or ESP. In an authentication policy on an interface or in an OSPF area, AH and ESP are used alone; in an encryption
policy, AH and ESP may be used together. The difference between the two mechanisms is the extent of the coverage. ESP only
protects IP header fields if they are encapsulated by ESP.
You decide the set of IPsec protocols that are employed for authentication and encryption and the ways in which they are
employed. When you correctly implement and deploy IPsec, it does not adversely affect users or hosts. AH and ESP are
designed to be cryptographic algorithm-independent.
OSPFv3 Authentication Using IPsec: Configuration Notes
OSPFv3 authentication using IPsec is implemented according to the specifications in RFC 4552.
● To use IPsec, configure an authentication (using AH) or encryption (using ESP) security policy on an interface or in an
OSPFv3 area. Each security policy consists of a security policy index (SPI) and the key used to validate OSPFv3 packets.
After IPsec is configured for OSPFv3, IPsec operation is invisible to the user.
○ You can only enable one security protocol (AH or ESP) at a time on an interface or for an area. Enable IPsec AH with the
ipv6 ospf authentication command; enable IPsec ESP with the ipv6 ospf encryption command.
○ The security policy configured for an area is inherited by default on all interfaces in the area.
○ The security policy configured on an interface overrides any area-level configured security for the area to which the
interface is assigned.
○ The configured authentication or encryption policy is applied to all OSPFv3 packets transmitted on the interface or in the
area. The IPsec security associations (SAs) are the same on inbound and outbound traffic on an OSPFv3 interface.
○ There is no maximum AH or ESP header length because the headers have fields with variable lengths.
● Manual key configuration is supported in an authentication or encryption policy (dynamic key configuration using the internet
key exchange [IKE] protocol is not supported).
● In an OSPFv3 authentication policy:
○ AH is used to authenticate OSPFv3 headers and certain fields in IPv6 headers and extension headers.
○ MD5 and SHA1 authentication types are supported; encrypted and unencrypted keys are supported.
● In an OSPFv3 encryption policy:
○ Both encryption and authentication are used.
○ IPsec security associations (SAs) are supported only in Transport mode (Tunnel mode is not supported).
○ ESP with null encryption is supported for authenticating only OSPFv3 protocol headers.
○ ESP with non-null encryption is supported for full confidentiality.
○ 3DES, DES, AES-CBC, and NULL encryption algorithms are supported; encrypted and unencrypted keys are supported.
Open Shortest Path First (OSPFv2 and OSPFv3)
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