{"id":952,"date":"2025-09-08T10:06:41","date_gmt":"2025-09-08T10:06:41","guid":{"rendered":"https:\/\/www.rajeshkumar.xyz\/blog\/?p=952"},"modified":"2025-09-08T11:14:19","modified_gmt":"2025-09-08T11:14:19","slug":"iam-identity-and-access-management-a-complete-guide","status":"publish","type":"post","link":"https:\/\/www.rajeshkumar.xyz\/blog\/iam-identity-and-access-management-a-complete-guide\/","title":{"rendered":"IAM (Identity and Access Management)  &#8211; A Complete Guide"},"content":{"rendered":"\n<p>There are 2 PEOPLE who wants to consume IAM<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Human to Service<\/li>\n\n\n\n<li>Service to Service<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">What is Identity in IAM?<\/h3>\n\n\n\n<p>In IAM, an <strong>identity<\/strong> represents <strong>a person, a system, or a service<\/strong> that needs access to resources.<\/p>\n\n\n\n<p>Think of <strong>identity<\/strong> as the <strong>digital profile<\/strong> that IAM uses to know <em>who is asking for access<\/em>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Examples of Identities in IAM<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Human users<\/strong> \u2192 employees, admins, customers<\/li>\n\n\n\n<li><strong>Non-human users<\/strong> \u2192 applications, APIs, servers, bots<\/li>\n\n\n\n<li><strong>Groups \/ Roles<\/strong> \u2192 collections of users with similar permissions<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Why is Identity Important in IAM?<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Authentication (Who are you?)<\/strong><br>The system checks your identity (username, certificate, API key, etc.).<br>Example: <em>Rajesh logs in with his company email + password.<\/em><\/li>\n\n\n\n<li><strong>Authorization (What can you do?)<\/strong><br>Once identity is confirmed, IAM decides what resources you can access.<br>Example: <em>Rajesh can view reports but cannot delete databases.<\/em><\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Real-World Analogy<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Identity<\/strong> = Your company badge with your name &amp; photo.<\/li>\n\n\n\n<li><strong>Authentication<\/strong> = Security guard scanning the badge to confirm it\u2019s real.<\/li>\n\n\n\n<li><strong>Authorization<\/strong> = Deciding which office rooms your badge can open.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p>\ud83d\udc49 <strong>In short:<\/strong><br>In IAM, <strong>identity<\/strong> is the digital representation of a user or service. It\u2019s the \u201cwho\u201d in the system, used as the foundation for authentication and authorization.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p>Let\u2019s break down the <strong>main components of Identity and Access Management (IAM)<\/strong> in a simple and structured way.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83d\udd11 Core Components of IAM<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">1. <strong>Identity<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Definition:<\/strong> The digital representation of a person, group, or system.<\/li>\n\n\n\n<li><strong>Examples:<\/strong> Users, service accounts, roles, groups.<\/li>\n\n\n\n<li><strong>Purpose:<\/strong> Establishes <em>who<\/em> is trying to access resources.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">2. <strong>Authentication<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Definition:<\/strong> Verifying that an identity is genuine.<\/li>\n\n\n\n<li><strong>Examples:<\/strong> Passwords, OTP, biometrics (fingerprint, face ID), security tokens, certificates.<\/li>\n\n\n\n<li><strong>Purpose:<\/strong> Confirms <em>you are who you claim to be<\/em>.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">3. <strong>Authorization<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Definition:<\/strong> Defining what authenticated identities are allowed to do.<\/li>\n\n\n\n<li><strong>Examples:<\/strong> RBAC (Role-Based Access Control), ABAC (Attribute-Based Access Control), policies.<\/li>\n\n\n\n<li><strong>Purpose:<\/strong> Ensures you have the <em>right permissions<\/em> for the requested resource.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">4. <strong>User Management &amp; Lifecycle<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Definition:<\/strong> Processes for creating, updating, disabling, and deleting user accounts.<\/li>\n\n\n\n<li><strong>Examples:<\/strong> Onboarding new employees, offboarding exiting staff, updating roles when someone gets promoted.<\/li>\n\n\n\n<li><strong>Purpose:<\/strong> Keeps access clean, secure, and up-to-date.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">5. <strong>Access Management<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Definition:<\/strong> Enforcing rules on how identities gain access to systems\/resources.<\/li>\n\n\n\n<li><strong>Examples:<\/strong> Single Sign-On (SSO), MFA (Multi-Factor Authentication), Just-In-Time access.<\/li>\n\n\n\n<li><strong>Purpose:<\/strong> Securely manages how users log in and access multiple apps.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">6. <strong>Directory Services<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Definition:<\/strong> Central repositories storing identity data.<\/li>\n\n\n\n<li><strong>Examples:<\/strong> Active Directory (AD), LDAP directories, AWS IAM directory.<\/li>\n\n\n\n<li><strong>Purpose:<\/strong> Acts as the \u201cphonebook\u201d of users, groups, and policies.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">7. <strong>Governance &amp; Compliance<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Definition:<\/strong> Policies, monitoring, and audits to ensure proper use of IAM.<\/li>\n\n\n\n<li><strong>Examples:<\/strong> Access reviews, role audits, segregation of duties.<\/li>\n\n\n\n<li><strong>Purpose:<\/strong> Ensures organizations follow regulations (GDPR, HIPAA, ISO, SOC2, etc.).<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">8. <strong>Monitoring &amp; Reporting<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Definition:<\/strong> Tracking and analyzing identity-related activities.<\/li>\n\n\n\n<li><strong>Examples:<\/strong> Audit logs, SIEM alerts, unusual login detection.<\/li>\n\n\n\n<li><strong>Purpose:<\/strong> Detects threats, prevents misuse, and ensures accountability.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83c\udfd7\ufe0f Quick Analogy<\/h2>\n\n\n\n<p>Imagine a <strong>secure office building<\/strong>:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Identity<\/strong> = Employee badge with your name.<\/li>\n\n\n\n<li><strong>Authentication<\/strong> = Security guard scans the badge.<\/li>\n\n\n\n<li><strong>Authorization<\/strong> = Badge opens only specific floors\/rooms.<\/li>\n\n\n\n<li><strong>User Lifecycle<\/strong> = Badge created when you join, disabled when you leave.<\/li>\n\n\n\n<li><strong>Access Management<\/strong> = One badge works for all company doors (SSO).<\/li>\n\n\n\n<li><strong>Directory<\/strong> = Employee database with all roles.<\/li>\n\n\n\n<li><strong>Governance<\/strong> = Regular audits of who has access to which rooms.<\/li>\n\n\n\n<li><strong>Monitoring<\/strong> = Security cameras &amp; logs tracking who entered where.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">How Login Session Work with Flow  (Human User)<\/h2>\n\n\n\n<p><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">\ud83d\udd11 Login Session Flow (Human User Using Browser)<\/h1>\n\n\n\n<h3 class=\"wp-block-heading\">1. <strong>User Enters Credentials<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>You type your <strong>username\/email<\/strong> and <strong>password<\/strong> on the login page.<\/li>\n\n\n\n<li>Sometimes extra security is added (OTP, fingerprint, etc.).<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">2. <strong>Website Checks Credentials<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The website\u2019s server looks up your identity in its database.<\/li>\n\n\n\n<li>If the password (after hashing) matches, it says: \u2705 <em>You are who you claim to be.<\/em><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">3. <strong>Session\/Token is Created<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The server creates a <strong>session record<\/strong> (like a visitor badge).<\/li>\n\n\n\n<li>This contains your <strong>user ID, login time, and permissions<\/strong>.<\/li>\n\n\n\n<li>The server generates a random <strong>session ID\/token<\/strong> that points to this record.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">4. <strong>Token is Sent to Browser<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The session ID\/token is stored in your <strong>browser cookie<\/strong> (or local storage if it\u2019s token-based).<\/li>\n\n\n\n<li>Example: <code>Set-Cookie: session_id=abc123; Secure; HttpOnly<\/code><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">5. <strong>Browser Reuses Token<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>For every new click or page you open, your browser automatically sends the token back.<\/li>\n\n\n\n<li>The website checks: <em>Is this session still valid?<\/em> If yes \u2192 it lets you continue without logging in again.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">6. <strong>Authorization (What You Can Do)<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Based on your identity, the server decides:\n<ul class=\"wp-block-list\">\n<li><em>Normal user \u2192 can view content<\/em><\/li>\n\n\n\n<li><em>Admin \u2192 can also edit or delete<\/em><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">7. <strong>Session Timeout<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>If you stay idle too long (say 30 min), the session expires.<\/li>\n\n\n\n<li>You\u2019ll need to log in again.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">8. <strong>Logout<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>When you click logout:\n<ul class=\"wp-block-list\">\n<li>The website deletes the session from its server.<\/li>\n\n\n\n<li>Your browser cookie\/token is cleared.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Now, even if someone steals your old token, it won\u2019t work.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83c\udfe2 Real-Life Analogy<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Login = Showing your ID card at building security<\/strong><\/li>\n\n\n\n<li><strong>Session token = Visitor badge given to you<\/strong><\/li>\n\n\n\n<li><strong>Cookie in browser = You keep wearing the badge<\/strong><\/li>\n\n\n\n<li><strong>Authorization = Which rooms your badge opens<\/strong><\/li>\n\n\n\n<li><strong>Logout\/Expire = Badge deactivated, you must check in again<\/strong><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p>\ud83d\udc49 In short:<br>When you log in, the website verifies your identity, gives your browser a <strong>session token<\/strong>, and then uses that token to recognize you on every request until you log out or it expires.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">How <strong>Service A authenticates to Service B<\/strong>?<\/h2>\n\n\n\n<p>Alright \ud83d\udc4d Let\u2019s make it <strong>super simple<\/strong> \u2014 how <strong>Service A authenticates to Service B<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Step-by-Step (Simple Words)<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">1. Service A needs to call Service B<\/h3>\n\n\n\n<p>Example: <strong>Payment service (A)<\/strong> needs to call <strong>Order service (B)<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">2. Service A gets a \u201ctoken\u201d<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Service A asks a <strong>trusted Identity Provider (IdP)<\/strong> (like Keycloak, AWS IAM, Azure AD).<\/li>\n\n\n\n<li>IdP checks who Service A is (using a secret, certificate, or workload identity).<\/li>\n\n\n\n<li>IdP gives Service A a <strong>token<\/strong> (like a signed digital badge).<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">3. Service A sends a request with the token<\/h3>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"HTML, XML\" data-shcb-language-slug=\"xml\"><span><code class=\"hljs language-xml\">GET \/orders\nHost: service-b.example.com\nAuthorization: Bearer <span class=\"hljs-tag\">&lt;<span class=\"hljs-name\">token<\/span>&gt;<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">HTML, XML<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">xml<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">4. Service B receives the request<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Service B looks at the <strong>token<\/strong> in the request.<\/li>\n\n\n\n<li>It checks:\n<ul class=\"wp-block-list\">\n<li>Is the token <strong>real<\/strong> (signature valid)?<\/li>\n\n\n\n<li>Is it still <strong>valid<\/strong> (not expired)?<\/li>\n\n\n\n<li>Is it really <strong>meant for Service B<\/strong> (audience claim)?<\/li>\n\n\n\n<li>What <strong>permissions<\/strong> does it give (scopes\/roles)?<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">5. Service B decides<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>If all checks pass \u2192 Service B <strong>trusts Service A<\/strong> and serves the request.<\/li>\n\n\n\n<li>If not \u2192 Service B <strong>rejects<\/strong> (401 Unauthorized).<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">6. Token refresh<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Tokens usually expire quickly (5\u201315 min).<\/li>\n\n\n\n<li>Service A must ask the IdP for a <strong>new token<\/strong> before calling again.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83d\udd11 Analogy<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Service A = Delivery driver<\/strong> \ud83d\ude9a<\/li>\n\n\n\n<li><strong>IdP = Security office<\/strong> \ud83d\udee1\ufe0f (gives a visitor pass).<\/li>\n\n\n\n<li><strong>Token = Visitor pass<\/strong> \ud83c\udf9f\ufe0f (signed, valid for a short time).<\/li>\n\n\n\n<li><strong>Service B = Warehouse<\/strong> \ud83c\udfed (only lets in drivers with a valid pass).<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p>\ud83d\udc49 In short:<br><strong>Service A proves who it is by getting a token from a trusted authority, then shows that token to Service B. Service B checks the token before allowing access.<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p>Do you want me to explain this again with a <strong>real-life example using JWT claims<\/strong> (like <code>iss<\/code>, <code>aud<\/code>, <code>exp<\/code>, <code>scope<\/code>) so you see exactly what\u2019s inside the token Service A shows to Service B?<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Where Laravel\/Passport concepts map (still conceptual)<\/h2>\n\n\n\n<p>Great, let\u2019s keep it purely conceptual and Laravel-flavored with <strong>Passport<\/strong> as the identity server.<\/p>\n\n\n\n<p>Think of the three apps like this:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>ServiceA (Identity)<\/strong>: Your <strong>Authorization Server<\/strong> (issues OAuth2 access\/ID tokens; holds the user login session).<\/li>\n\n\n\n<li><strong>ServiceB<\/strong> and <strong>ServiceC<\/strong>: Separate Laravel apps that are both <strong>OAuth2 Clients<\/strong> (to ask for tokens) and <strong>Resource Servers<\/strong> (to protect their own APIs). They <strong>trust<\/strong> tokens minted by ServiceA.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Core ideas (in Passport terms)<\/h1>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>One login place:<\/strong> Users authenticate <strong>only at ServiceA<\/strong>.<\/li>\n\n\n\n<li><strong>Tokens, not passwords:<\/strong> ServiceA issues <strong>access tokens (JWT)<\/strong> carrying scopes\/claims.<\/li>\n\n\n\n<li><strong>Trust via keys:<\/strong> B and C <strong>validate<\/strong> those tokens using ServiceA\u2019s public key (so they never need to know user passwords).<\/li>\n\n\n\n<li><strong>Scopes\/audience:<\/strong> Tokens carry <strong>what<\/strong> the caller can do (e.g., <code>servicec.read<\/code>) and <strong>who<\/strong> they\u2019re meant for (conceptually \u201caudience = ServiceC\u201d).<\/li>\n\n\n\n<li><strong>Sessions vs tokens:<\/strong>\n<ul class=\"wp-block-list\">\n<li>Browser \u201clogged in\u201d = <strong>session cookie<\/strong> inside each app (B or C).<\/li>\n\n\n\n<li>API calls between apps = <strong>Bearer token<\/strong> issued by A.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q1) \u201cUser authenticates using ServiceB\u2014how does B also get access to ServiceC?\u201d<\/h1>\n\n\n\n<p>This is the <strong>user-delegated<\/strong> scenario. Flow at a high level:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>User hits a protected page on B.<\/strong><br>B sees \u201cno user\u201d and <strong>redirects to ServiceA<\/strong> (OAuth Authorization Code flow, typically with PKCE).<\/li>\n\n\n\n<li><strong>User logs in at ServiceA.<\/strong><br>ServiceA now has a <strong>user session<\/strong> (at A). It redirects back to B with a one-time <strong>authorization code<\/strong>.<\/li>\n\n\n\n<li><strong>B exchanges that code (server-side) with A<\/strong> for tokens:\n<ul class=\"wp-block-list\">\n<li><strong>ID token<\/strong> (who the user is),<\/li>\n\n\n\n<li><strong>Access token<\/strong> (what the user can access), possibly a <strong>refresh token<\/strong>.<br>B validates and then creates a <strong>Laravel session<\/strong> for the browser (so page views on B don\u2019t need to carry the access token).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>B needs data from C.<\/strong> Two clean patterns:\n<ul class=\"wp-block-list\">\n<li><strong>Propagate the user\u2019s token<\/strong>: If the access token already contains scopes good for C (e.g., <code>servicec.read<\/code>) and C is configured to accept tokens from A, <strong>B calls C<\/strong> with <code>Authorization: Bearer &lt;that token><\/code>.<br>C validates the token (signature, expiry, issuer, required scopes) and serves the request.<\/li>\n\n\n\n<li><strong>Least-privilege \u201cretargeting\u201d (token exchange concept):<\/strong> B asks A for a <strong>new access token specifically for C<\/strong> with only the scopes C needs (e.g., <code>servicec.read<\/code>). Then B calls C with this C-scoped token.<br>(Passport doesn\u2019t ship IETF Token Exchange out of the box; conceptually, you model this by asking A for the right scopes destined for C and having C enforce them.)<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>C authorizes<\/strong> based on the token\u2019s scopes\/claims and returns data to B.<\/li>\n<\/ol>\n\n\n\n<p><strong>Mental model:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The <strong>browser talks to B<\/strong> with a session cookie.<\/li>\n\n\n\n<li><strong>B talks to C<\/strong> with a <strong>Bearer token<\/strong> from A.<\/li>\n\n\n\n<li><strong>C trusts only A\u2019s tokens<\/strong> and its required scopes.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">Q2) \u201cHow does logging in once (at ServiceA) log the user into <strong>all<\/strong> services?\u201d<\/h1>\n\n\n\n<p>This is <strong>SSO via the identity server\u2019s session<\/strong>:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>First app (say B):<\/strong><br>The first time the user encounters a protected page on B, B redirects them to A. The user enters credentials at <strong>A<\/strong>. Now <strong>A holds a login session<\/strong> for that browser.<\/li>\n\n\n\n<li><strong>Second app (C):<\/strong><br>Later, the user visits C. C also redirects to A (same OIDC\/OAuth flow). <strong>But the user is already logged in at A<\/strong>, so A <strong>doesn\u2019t prompt again<\/strong>\u2014it immediately issues a fresh authorization code back to C, and C exchanges it for tokens.<br>Result: the user appears \u201cauto-logged-in\u201d at C without re-entering credentials.<\/li>\n\n\n\n<li><strong>Local sessions per app:<\/strong><br>Each app (B, C) still creates <strong>its own Laravel session<\/strong> after receiving tokens. That\u2019s why navigating within each app feels logged-in. The \u201csingle\u201d part of SSO comes from the <strong>central session at A<\/strong> that silently re-authenticates apps on demand.<\/li>\n\n\n\n<li><strong>Logout reality check:<\/strong>\n<ul class=\"wp-block-list\">\n<li>Logging out of B clears B\u2019s session. To make it feel like a global logout, <strong>B should also send the browser to ServiceA\u2019s logout<\/strong>.<\/li>\n\n\n\n<li>If A\u2019s session is closed, the next time the user hits any app (B or C), they\u2019ll be redirected to A and asked to log in again.<\/li>\n\n\n\n<li>Without coordinated back-channel logout, already-open apps won\u2019t instantly know the user logged out elsewhere. Most teams accept \u201clogout at app + logout at A\u201d as practical SSO.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Where Laravel\/Passport concepts map (still conceptual)<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>ServiceA (Passport server):<\/strong><br>Holds <strong>users<\/strong>, login UI, and <strong>issues tokens<\/strong>. Maintains the <strong>central SSO session<\/strong> in the browser.<\/li>\n\n\n\n<li><strong>ServiceB\/ServiceC (clients + resource servers):<\/strong>\n<ul class=\"wp-block-list\">\n<li>As <strong>clients<\/strong>: redirect to A when unauthenticated; exchange the authorization code for tokens; create a <strong>local Laravel session<\/strong>.<\/li>\n\n\n\n<li>As <strong>resource servers<\/strong>: protect APIs by <strong>validating Bearer tokens<\/strong> from A (signature, issuer, expiry, scopes).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Scopes \/ claims:<\/strong><br>Use scopes to represent permissions that <strong>C<\/strong> enforces (e.g., <code>servicec.read<\/code>, <code>servicec.write<\/code>). <strong>B requests only what it needs<\/strong>.<\/li>\n\n\n\n<li><strong>Token lifetimes:<\/strong><br>Keep <strong>access tokens short-lived<\/strong> (minutes). The browser experience remains smooth because the <strong>SSO session at A<\/strong> can mint fresh tokens without re-prompting the user.<\/li>\n\n\n\n<li><strong>Trust:<\/strong><br>B and C <strong>never share passwords or sessions<\/strong> with each other. They only trust <strong>tokens minted by A<\/strong> and <strong>their own local sessions<\/strong>.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Quick chooser<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>User viewing B \u25c0\ufe0e\u25b6\ufe0e B needs C\u2019s data:<\/strong><br>B uses <strong>A-issued token<\/strong> to call C (propagate or \u201cretarget\u201d to least privilege).<\/li>\n\n\n\n<li><strong>User lands on C first:<\/strong><br>C also redirects to <strong>A<\/strong>; A\u2019s existing session makes it seamless SSO.<\/li>\n\n\n\n<li><strong>Background\/cron\/no user:<\/strong><br>Use <strong>client credentials<\/strong> from A for B\u2192C calls (represents B itself, not a user).<\/li>\n<\/ul>\n\n\n\n<p>That\u2019s the big picture: <strong>ServiceA is the single source of truth<\/strong> (login + tokens), <strong>B and C trust A<\/strong>, and <strong>SSO happens because A keeps the only real login session<\/strong> and reissues tokens to any app that asks.<\/p>\n\n\n\n<p>Great question\u2014keeping it 100% conceptual and Passport-flavored.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Who creates \u201cclients\u201d and where?<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Short answer<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Create all OAuth clients in <em>ServiceA<\/em> (the Identity\/Authorization Server).<\/strong><\/li>\n\n\n\n<li><strong>ServiceB and ServiceC do not create OAuth clients locally<\/strong> (unless they themselves need to call other services as a client\u2014then they get a client entry in <strong>ServiceA<\/strong> too).<\/li>\n\n\n\n<li><strong>ServiceB\/C just <em>use<\/em> those clients<\/strong> (by configuring the client_id\/secret and ServiceA URLs in their app settings) and <strong>validate tokens issued by ServiceA<\/strong>.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">What \u201cclient\u201d entries do you need in ServiceA?<\/h2>\n\n\n\n<p>Think in terms of <strong>who needs a token from A<\/strong> and <strong>for what flow<\/strong>:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Browser login to B (or C)<\/strong> \u2192 <strong>Authorization Code client<\/strong> (for each UI app)\n<ul class=\"wp-block-list\">\n<li>Create <strong>one client for ServiceB\u2019s web\/UI<\/strong> in <strong>ServiceA<\/strong> (with B\u2019s redirect URI).<\/li>\n\n\n\n<li>If ServiceC also has a user-facing UI, create <strong>one client for ServiceC\u2019s web\/UI<\/strong> (with C\u2019s redirect URI).<\/li>\n\n\n\n<li>Purpose: lets each app redirect users to A and get back tokens (SSO).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>B calls C without a user (cron\/background\/webhook)<\/strong> \u2192 <strong>Client Credentials client<\/strong> (for B)\n<ul class=\"wp-block-list\">\n<li>Create <strong>one machine client for ServiceB<\/strong> in <strong>ServiceA<\/strong> with client credentials enabled.<\/li>\n\n\n\n<li>Purpose: gives B a \u201cservice identity\u201d to fetch access tokens from A to call C.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>If <strong>C<\/strong> ever calls something else as a backend, <strong>C<\/strong> gets its own <strong>client credentials<\/strong> client in <strong>ServiceA<\/strong> as well.<\/p>\n<\/blockquote>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Where do these go (conceptually \u201cinserted\u201d)?<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>ServiceA (Identity)<\/strong>\n<ul class=\"wp-block-list\">\n<li>You <strong>register<\/strong> the clients (above) in <strong>ServiceA\u2019s Passport<\/strong> (i.e., entries in <code>oauth_clients<\/code> with names, secrets, and <strong>redirect URIs<\/strong> for UI apps).<\/li>\n\n\n\n<li>You also define <strong>scopes<\/strong>\/permissions that APIs (like C) will enforce (e.g., <code>servicec.read<\/code>, <code>servicec.write<\/code>).<\/li>\n\n\n\n<li>ServiceA holds the <strong>user login session<\/strong> (this is what makes SSO feel \u201csingle\u201d).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>ServiceB \/ ServiceC (Apps\/APIs)<\/strong>\n<ul class=\"wp-block-list\">\n<li>As <strong>OAuth Clients<\/strong>: they <strong>configure<\/strong> the <strong>client_id\/secret<\/strong> that you created in ServiceA (plus ServiceA\u2019s auth\/token endpoints and their own redirect URI). They don\u2019t create clients locally; they just reference the ones created in A.<\/li>\n\n\n\n<li>As <strong>Resource Servers<\/strong>: they <strong>validate Bearer tokens<\/strong> that came from ServiceA (signature, issuer, expiry, scopes). No \u201cclient\u201d is created here for validation; they just trust ServiceA\u2019s public key and enforce scopes.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">How does this answer your two scenarios?<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">1) \u201cUser authenticates using ServiceB and also gets access to ServiceC?\u201d<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>User hits <strong>B<\/strong> \u2192 B uses its <strong>Authorization Code client (in A)<\/strong> \u2192 user logs in at <strong>A<\/strong> \u2192 A issues tokens \u2192 B creates a local session.<\/li>\n\n\n\n<li>When B calls <strong>C<\/strong>:\n<ul class=\"wp-block-list\">\n<li><strong>With user context<\/strong>: B presents a token from <strong>A<\/strong> that C accepts (either the same user token with proper scopes, or a token specifically \u201ctargeted\u201d for C requested from A).<\/li>\n\n\n\n<li><strong>C trusts A<\/strong>, checks scopes, serves the request.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>All the client definitions that make this possible <strong>live in A<\/strong>.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">2) \u201cLogin with ServiceA once, then login to all services\u201d<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>First app (B) redirects to <strong>A<\/strong>, user logs in, <strong>A<\/strong> keeps a session.<\/li>\n\n\n\n<li>Second app (C) also redirects to <strong>A<\/strong> using <strong>its own Authorization Code client<\/strong>; because the user already has a session at A, A immediately issues tokens\u2014<strong>no second password prompt<\/strong>.<\/li>\n\n\n\n<li>Again, this works because <strong>both B and C are registered as clients in A<\/strong> and both redirect to the same identity session at A.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Mental checklist<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>In ServiceA (Passport):<\/strong>\n<ul class=\"wp-block-list\">\n<li>Create <strong>Authorization Code<\/strong> client for <strong>B UI<\/strong> (+ redirect URI of B).<\/li>\n\n\n\n<li>Create <strong>Authorization Code<\/strong> client for <strong>C UI<\/strong> (if it has UI) (+ redirect URI of C).<\/li>\n\n\n\n<li>Create <strong>Client Credentials<\/strong> client for <strong>B<\/strong> (if B calls C without a user).<\/li>\n\n\n\n<li>Define <strong>scopes<\/strong> that <strong>C<\/strong> will enforce.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>In ServiceB\/C apps:<\/strong>\n<ul class=\"wp-block-list\">\n<li>Configure to <strong>use<\/strong> those clients (client_id\/secret, endpoints, redirect URI).<\/li>\n\n\n\n<li>Protect APIs by <strong>validating tokens from A<\/strong> and <strong>enforcing scopes<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<p>That\u2019s it: <strong>all client registrations live in ServiceA<\/strong>; <strong>ServiceB\/C only reference them and validate A\u2019s tokens<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>There are 2 PEOPLE who wants to consume IAM What is Identity in IAM? In IAM, an identity represents a [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-952","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/posts\/952","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/comments?post=952"}],"version-history":[{"count":5,"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/posts\/952\/revisions"}],"predecessor-version":[{"id":959,"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/posts\/952\/revisions\/959"}],"wp:attachment":[{"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/media?parent=952"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/categories?post=952"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rajeshkumar.xyz\/blog\/wp-json\/wp\/v2\/tags?post=952"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}