Backups, Redundancy, and the Cloud: Computer Security Lectures 2014/15 S1

• published: 05 Jan 2015
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This video is part of the computer/information/cyber security and ethical hacking lecture series; by Z. Cliffe Schreuders at Leeds Beckett University. Laboratory work sheets, slides, and other open educational resources are available at http://z.cliffe.schreuders.org. The slides themselves are creative commons licensed CC-BY-SA, and images used are licensed as individually attributed. Topics covered in this lecture include: Backups and Redundancy confidentiality, integrity, and availability Objectives Recover from events Prevent problems Data Backups Backups can help mitigate various risks Backup plans The plan should meet any Recovery Point Objectives (RPO) and Recovery Time Objectives (RTO) Specifies: Who, how, and how often backups occur, How and for how long backups are stored, Where backups are stored, What data is backed up, How to recover backed up data Backup plan considerations: Value of data, vs cost of backup, how fast does recovery need to happen? Backup media Types of backup: Direct attached storage, Network-based, Internet/cloud, Network attached storage (NAS) Networked systems and filesystems Backup levels Epoch (full) backup: Everything is copied Differential backup: Only changes since the last full backup Delta encoding: stores the differences between versions, rather than complete copies Incremental backup: Only changes since the last backup (including differential backups) Multilevel backup involves levels: Level 0 = Full backup For example, monthly Level 1 = Changes since level 0 backup Multilevel differential Multilevel incremental Restoring a file from three-level backup Restoring an entire system Other backup methods System images Continuous data protection: Real-time backup, saves every change to a backup storage Version control: Commits versions of files to a repository, Preserves entire history, Eg: Git, Subversion Storage considerations Security of backups Physical security Encryption (esp. if stored off-site) File permissions, if stored on servers Data retention laws Backup software Lots of backup tools available, including free and proprietary solutions Software considerations Many provide a graphical front-end to standard Linux/Unix tools (for example ark) cp, tar (tape archive), dd (data dump), cpio, dump/restore, rsync - copy differences, over a network, rcp: insecure copy across network (don't use this), scp Redundancy Data redundancy, such as RAID Hardware redundancy Power redundancy Server redundancy Redundancy advantages and disadvantages Redundant array of inexpensive / independent disks (RAID) Hardware-based RAID Software-based RAID Choosing Hardware or software RAID Firmware-based RAID RAID levels Data striping: Segments sequential data and places it across drives Parity: Error detection, and in the case of RAID, error correction Mirroring: disks containing the same data RAID levels RAID 0: striping, no redundancy RAID 1: mirroring RAID 3: striping, dedicated parity disk RAID 5: like 3, but parity is stored along with data across all disks RAID 6: like 5, but two parity blocks Hot spare: An extra disk, not used until a failure, may automatically rebuild onto the spare Capacity RAID and Linux Need to monitor the logs for disk failures Log shipping Log shipping AKA warm standby Load balancing: distribute workload to redundant hardware Failover: a load balancer can stop sending requests to hardware that is not available Redundancy is not backup Backups can go wrong Backups can help Cloud computing: a network of remote servers providing services: Infrastructure as a Service (IaaS) – hosts VMs, such as servers or desktops (VDI) Platform as a Service (PaaS) – hosts access to a managed server to host software Software as a Service (SaaS) – use remote software The Cloud: provisioning uses virtualisation: hardware independent Resource pooling: resources assigned from a pool Elasticity: based on real time needs Agility and scale The Cloud: deployment - Public/Private/Hybrid cloud Redundancy and the Cloud Failover to a caching service Backups and the Cloud SaaS data storage services Consumer storage: Google Drive, Dropbox, Amazon Cloud Drive Online backups / data storage Encrypted backup Security and the Cloud Multi-tenant Many physical servers OS, platform, database, virtual network, and app security A single security breach can have wide reaching impact Data is stored and processed on computers owned and operated by someone else Privacy issues Legal and compliance issues Out of your control Conclusion