Be A Ninja With The OSI/DoD Models
OSI and DoD Models
Ports, well-known and otherwise
NAT and Private Address Ranges (thanks JP)
Basic Terminology
Asset – anything valuable, such as information, software or a car stereo
Threat – any event or object that might result in a loss, like theft or fire damage
Threat Agent – any person or thing that can carry out a threat, like a thief or a flood
Vulnerability – a weakness in security, like an unprotected server or a hole in a fence
Exploit – a way to actually take advantage of a weakness, for instance by attacking an unprotected server or going through that hole in the fence
Risk – the likelihood that that an exploit will actually be performed
Risk management is what it’s all about: how much risk can you tolerate, and how much will you spend to avoid it?
Information Security Provides
According to CompTIA:
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- Confidentiality – Only authorized persons have access to the information.
- Integrity – Insurance that a message, software or other item hasn’t been changed in any way.
- Availability – Information is available to properly authorized users.
Other sources discuss:
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- Privacy – Only authorized persons know that information exists. Security practices acknowledge the importance of Privacy, but security certifications walk glassy-eyed right past it.
- Non-repudiation -The impossibility of denying that information comes from a specific source.
- Authenticity – An affirmation that information is intact (has Integrity) and comes from the stated source (Non-repudiation). CompTIA does not use this term, but it’s common on other tests, e.g. the CEH.
While proper network security provides these benefits:
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- Authentication – Providing both a username (Identification) and a password or something similar (Authentication).
- Authorization – The permissions granted by the entity providing access, for instance share access permissions in Active Directory. People also call this Permissions, though usually that’s more correctly applied to individual settings rather than the collective environment of Authorization. See how smart you are now?
- Audit/Accounting – The ability to review accesses and actions of resources.
Basic Security Concepts
Layering -Providing multiple layers of protection: physical access control, a firewall, antivirus software, etc. The key concept is preventing one layer’s configuration from compromising other layers. If you leave workstations logged in overnight to distribute antivirus updates, you’ve weakened security with that compromise.
Limiting – Basically, limiting access, whether physical or logical.
Diversity – Using more than one type of a given security method; for instance, both a physical and a software firewall.
Obscurity – Limiting the information available to attackers. For example, your web server should not reveal that it’s Apache 1.2.
Simplicity – Put simply, don’t make your security layers hard to understand or configure.
Very Non-Basic Security Concepts
Trust Analysis
The Moebius Defense