Security Groups Hands on

So we’ve launched our EC2 instance — great!

🚀 Now let’s actually explore security groups in action.

🔍 Step 1: Viewing Security Groups from EC2

• From your EC2 instance page

• Go to Security tab

• You’ll see: Attached security groups, Inbound rules and Outbound rules

👉 This gives you a quick overview, but not the full picture.

🧭 Step 2: Open the Full Security Groups Page

For a deeper view:

1. Go to the left-hand menu

2. Under Networking & Security

3. Click on Security Groups

4. Now you’ll see all security groups in your account.

📦 Step 3: Understanding What You See

You’ll typically see:

• Default Security Group

• launch-wizard-1 (created when launching EC2)

Each security group has: 🆔 A unique Security Group ID, 📥 Inbound rules and 📤 Outbound rules

📥 Step 4: Inspect Inbound Rules

Inbound rules control who's allowed to reach your EC2 instance.

Click Edit Inbound Rules and you'll see something like:

• SSH — port 22 — source 0.0.0.0/0 (anywhere)

• HTTP — port 80 — source 0.0.0.0/0

🌐 Step 5: Why Your Website Worked

Earlier, you accessed your EC2 using its public IPv4 address

👉 That worked because of this rule:

HTTP (port 80) open to the internet

🚨 Step 6: Breaking It (Very Important Learning)

1. ❌ Delete the HTTP (port 80) rule

2. Save changes

3. Refresh your browser

👉 Result: You’ll see infinite loading / timeout

⚠️ Timeout = Security Group

Seeing a timeout — SSH, a website, an API, anything — check the security group first. It's almost always the cause.

Golden rule: Timeout = blocked by a security group.

✅ Step 7: Fixing the Issue

1. Add a new rule:

   • Type: HTTP

   • Port: 80

   • Source: 0.0.0.0/0

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2. Save rules

3. Refresh browser

4. ✅ Your website works again!

⚙️ Step 8: Adding Other Rules

What you can configure

Ports: open whatever you need — HTTPS (443), a custom port like 8080, or a whole range.

Source: decide who that port is open to —

• 🌍 Anywhere (0.0.0.0/0)

• 🧑 Only your IP ("My IP")

⚠️ One catch with "My IP": it's a snapshot, not a live setting. If your IP changes later — new network, ISP reassigns it, whatever — that rule no longer matches you, and you're locked out with a timeout until you update it.

📤 Step 9: Outbound Rules

Now take a look at Outbound Rules.

By default: all traffic is allowed, going anywhere.

That's what lets your EC2 instance freely reach out — hitting the internet, installing packages, calling external APIs — without you having to configure anything extra.

🔗 Multiple Security Groups

Important concept:

• ✅ One EC2 can have Multiple security groups

• ✅ One security group can be attached to Multiple EC2 instances

👉 Rules are combined together