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|The three faces of security|
The No. 1 consideration when designing an IP SAN is to treat it like an FC SAN. One of the things that makes FC so strong is that FC networks are small, tightly controlled and separated from other applications. The same precepts should be followed when designing the IP SAN: Only use iSCSI over private, tightly controlled LANs.
"The best IP SAN is an independent LAN using dedicated Ethernet switches," says Sanrad's Sante. So-called "air-gap" LANs are entirely disconnected from other Ethernet networks, and don't share the same hardware. At the very least, segmented VLANs and IP subnets should be employed to keep other traffic types away from your storage. And don't forget to secure the management interfaces on non-routed networks. Ideally, you should create a separate subnet for network management and allow only authorized users to access it through a VPN and firewall.
Without a tightly controlled, segmented network, iSCSI traffic and usage is likely to "leak" out of the data center. It's dangerous to allow PCs to access iSCSI devices from other parts of the network. One of the first things I did when testing an iSCSI array was to mount a LUN on my laptop over wireless Ethernet. Although functional, this type of connectivity is a security nightmare. Therefore, limit the reach of the IP SAN to the data center.
Follow these policies
If you're considering deploying iSCSI, you should follow these policies:
- Build a SAN, not a LAN. Treat iSCSI just as you would treat FC. Build a dedicated network for storage, and don't share switches or network cards between storage and other network traffic.
- Divide and conquer. Use ACLs and other LUN masking techniques to limit access to iSCSI LUNs to only valid clients.
- Lock the door. Use a separate, strong CHAP password for each iSCSI client and consider changing the passwords periodically.
- Restrict management. Use role-based security and accounting in management applications; limit even your own access to avoid accidents; and build a separate firewalled subnet for management interfaces.
- Encrypt data. Consider using client-based encryption to protect data across the network and on the disk, but be careful with your encryption keys.
|Policy vs. practicality|
This was first published in March 2005