How do I disable or enable the IPv6 protocol in Red Hat Enterprise Linux?

Issue

• How do I disable or enable the IPv6 protocol in Red Hat Enterprise Linux?
• When I attempt to disable IPv6 in RHEL 5, IPv4 does not connect.  I had to re-enable IPv6 via console commands to connect the server to the network.

• Why do I see errors when changing IPv6 kernel parameters?

  # sysctl -p
  error: "net.ipv6.conf.default.accept_redirects" is an unknown key
  error: "net.ipv6.conf.default.accept_ra" is an unknown key
  error: "net.ipv6.conf.all.disable_ipv6" is an unknown key
  error: "net.ipv6.conf.default.disable_ipv6" is an unknown key
  

• How do I automate IPv6 configuration to comply with security polices (like Center for Internet Security - CIS) with Security Content Automation Protocol (SCAP)?

  • Ensure IPv6 is disabled through kernel boot parameter
  • Disable IPv6 Addressing on All IPv6 Interfaces
  • Disable IPv6 Addressing on IPv6 Interfaces by Default
  • Disable IPv6 Networking Support Automatic Loading