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234 Fabric OS Administrator’s Guide
53-1002745-02
Management interface security
7
these values in negotiations to create IP sec SAs. You must create an SA prior to creating an
SA-proposal. You cannot modify an SA once it is created. Use the IP secConfig
--flush manual-sa
command to remove all SA entries from the kernel SADB and re-create the SA. For more
information on the IP secConfig command, refer to the Fabric OS Command Reference.
IP sec proposal
The IP sec sa-proposal defines an SA or an SA bundle. An SA is a set of parameters that define how
the traffic is protected using IP sec. These are the IP sec protocols to use for an SA, either AH or
ESP, and the encryption and authentication algorithms to use to protect the traffic. For SA bundles,
[AH, ESP] is the supported combination.
Authentication and encryption algorithms
IP sec uses different protocols to ensure the authentication, integrity, and confidentiality of the
communication. Encapsulating Security Payload (ESP) provides confidentiality, data integrity and
data source authentication of IP packets, and protection against replay attacks. Authentication
Header (AH) provides data integrity, data source authentication, and protection against replay
attacks, but unlike ESP, AH does not provide confidentiality.
In AH and ESP, hmac_md5 and hmac_sha1 are used as authentication algorithms. Only in ESP,
3des_cbc, blowfish_cbc, aes256_cbc and null_enc are used as encryption algorithms. Use
Table 46 when configuring the authentication algorithm.
IP sec policies
An IP sec policy determines the security services afforded to a packet and the treatment of a
packet in the network. An IP sec policy allows classifying IP packets into different traffic flows and
specifies the actions or transformations performed on IP packets on each of the traffic flows. The
main components of an IP sec policy are: IP packet filter and selector (IP address, protocol, and
port information) and transform set.
TABLE 46 Algorithms and associated authentication policies
Algorithm Encryption Level Policy Description
hmac_md5 128-bit AH, ESP A stronger MAC because it is a keyed hash inside a keyed hash. When
MD5 or SHA-1 is used in the calculation of an HMAC; the resulting MAC
algorithm is termed HMAC-MD5 or HMAC-SHA-1 accordingly.
NOTE: The MD5 hash algorithm is blocked when FIPS mode is
enabled
hmac_sha1 160-bit AH, ESP
3des_cbc 168-bit ESP Triple DES is a more secure variant of DES. It uses three different
56-bit keys to encrypt blocks of 64-bit plain text. The algorithm is
FIPS-approved for use by Federal agencies.
blowfish_cbc 64-bit ESP Blowfish is a 32-bit to 448-bit keyed, symmetric block cipher.
aes128_cbc 128-bit ESP Advanced Encryption Standard is a 128- or 256-bit fixed block size
cipher.
aes256_cbc 256-bit ESP
null_enc n/a ESP A form of plaintext encryption.