How deeply does Microsoft Azure in Action cover security rule?

Defines matching fields, ordered evaluation, default rules, and overlap risks without detailing packet-processing internals.

Security rule

As explained in Microsoft Azure in Action

A security rule is an ordered network-filtering rule that specifies traffic criteria and an allow or deny action.

A security rule filters traffic entering or leaving a network security group (NSG). It matches traffic by port, protocol, source, and destination, then allows or denies it. NSGs can protect a subnet or an individual VM through its network interface. section 4.3

The important settings are:

Priority runs from the lowest number to the highest; once a rule matches, later rules do not process that packet. section 4.3
Port accepts a number from 0 to 65,535 or Any, while protocol accepts TCP, UDP, or Any. section 4.3
Sources and destinations can be Any, an IP address, a CIDR range, or an Azure service tag. section 4.3
Action is Allow or Deny; overlapping rules deserve careful priorities, or the rule list can become network spaghetti. section 4.3

Allowing remote desktop

An Azure PowerShell configuration adds an inbound allowRDP rule for TCP port 3389, restricted to a specified source address, with priority 300. section 4.3

Table 4.3 Inbound security rules for a default NSG

Priority	Name	Port	Protocol	Source	Destination	Action
300	`SSH`	22	TCP	Any	Any	Allow
65000	`AllowVNetInbound`	Any	Any	VNet	VNet	Allow
65001	`AllowAzureLoadBalancer InBound`	Any	Any	Azure Load Balancer	Any	Allow
65002	`DenyAllInbound`	Any	Any	Any	Any	Deny

Compare a default NSG's SSH allow rule with its built-in VNet, load-balancer, and deny-all rules. section 4.3

How Microsoft Azure in Action covers it

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Also explained in

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Spring in Action, Sixth EditionA security rule is a declarative condition specifying the security requirements for requests matching particular URL paths or patterns.

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Related concepts

network security grouppart of · A network security group is an Azure access-control resource that filters inbound and outbound network traffic using prioritized security rules.
HttpSecurityconfigured by · HttpSecurity is a Spring Security configuration API for defining web request security rules, authentication mechanisms, and protection settings.
SecurityFilterChainconfigures · SecurityFilterChain is a Spring Security component that applies ordered security filters and request-security rules to incoming web requests.
vulnerabilitycontrasts with · A vulnerability is a weakness or susceptibility in a system, process, or person that can expose it to harm, misuse, failure, or compromise.
linter rulecontrasts with · A linter rule is a configurable condition applied by a linter to detect or enforce specified patterns or constraints in code or other artifacts.

This explainer was generated by Manning's knowledge graph from the text of Microsoft Azure in Action. The section links point to the parts of the book it draws on.