6.8. Using IPsec on a system with FIPS mode enabled

RHEL in Federal Information Processing Standard (FIPS) mode exclusively uses validated cryptographic modules, automatically disabling legacy protocols and ciphers. Enabling FIPS mode is often a requirement for federal compliance and enhances system security.

The Libreswan IPsec implementation provided by RHEL is fully FIPS-compliant. When the system is in FIPS mode, Libreswan automatically uses the certified cryptographic modules without requiring any additional configuration, regardless of whether Libreswan is installed on a new FIPS-enabled system or when FIPS mode is activated on a system with an existing Libreswan VPN.

If FIPS mode is enabled, you can confirm that Libreswan is running in FIPS mode:

# ipsec whack --fipsstatus
FIPS mode enabled

To list the allowed algorithms and ciphers in Libreswan in FIPS mode, enter:

# ipsec pluto --selftest 2>&1
...
FIPS Encryption algorithms:
  AES_CCM_16  {256,192,*128} IKEv1:  ESP  IKEv2:  ESP  FIPS   aes_ccm, aes_ccm_c
  AES_CCM_12  {256,192,*128} IKEv1:  ESP  IKEv2:  ESP  FIPS   aes_ccm_b
  AES_CCM_8   {256,192,*128} IKEv1:  ESP  IKEv2:  ESP  FIPS   aes_ccm_a
...