Azure SQL firewall rules - Step-by-Step Execution

Process Flow - Azure SQL firewall rules

Start: Azure SQL Server

↓

Check incoming connection IP

↓

Is IP in firewall rules?

No→Reject connection

Yes↓

Allow connection to database

↓

Connection established

Azure SQL checks the IP of incoming connections against firewall rules. If allowed, connection proceeds; otherwise, it is blocked.

Execution Sample

Azure

az sql server firewall-rule create --resource-group MyGroup --server MyServer --name AllowClientIP --start-ip-address 192.168.1.1 --end-ip-address 192.168.1.1

This command creates a firewall rule allowing the IP 192.168.1.1 to access the Azure SQL server.

Process Table

Step	Action	Input IP	Firewall Rules Checked	Result	Connection Status
1	Incoming connection attempt	192.168.1.1	No rules yet	No match	Rejected
2	Create firewall rule	192.168.1.1	Add rule 192.168.1.1 - 192.168.1.1	Rule added	N/A
3	Incoming connection attempt	192.168.1.1	Check rule 192.168.1.1 - 192.168.1.1	Match found	Allowed
4	Incoming connection attempt	192.168.1.2	Check rule 192.168.1.1 - 192.168.1.1	No match	Rejected

💡 Connection attempts stop after allowed or rejected based on firewall rules.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4
FirewallRules	[]	[192.168.1.1-192.168.1.1]	[192.168.1.1-192.168.1.1]	[192.168.1.1-192.168.1.1]
ConnectionIP	192.168.1.1	192.168.1.1	192.168.1.1	192.168.1.2
ConnectionStatus	Rejected	N/A	Allowed	Rejected

Key Moments - 2 Insights

Why was the first connection attempt rejected even though the IP was 192.168.1.1?

Because no firewall rules existed yet at step 1, so the IP was not allowed. The rule was added only at step 2.

Does the firewall rule allow IPs outside the specified range?

No, only IPs within the start and end IP addresses in the firewall rule are allowed, as shown at step 4 where 192.168.1.2 was rejected.

Visual Quiz - 3 Questions

Look at the execution table, what is the connection status at step 3 for IP 192.168.1.1?

A Rejected

B Pending

C Allowed

D Unknown

💡 Hint

Check the 'Connection Status' column at step 3 in the execution_table.

At which step is the firewall rule created?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Action' column for when the rule is added in the execution_table.

If the firewall rule allowed IP range 192.168.1.1 to 192.168.1.5, what would be the connection status for IP 192.168.1.4 at step 4?

A Allowed

B Rejected

C Pending

D Error

💡 Hint

Refer to the variable_tracker and execution_table logic about IP range matching.

Concept Snapshot

Azure SQL firewall rules control which IP addresses can connect.
Rules specify start and end IP addresses.
Incoming IPs are checked against these rules.
If IP matches, connection is allowed; otherwise, rejected.
Rules must be created before connections are accepted.

Full Transcript

Azure SQL firewall rules work by checking the IP address of any incoming connection against a list of allowed IP ranges. If the IP is within any allowed range, the connection is permitted. Otherwise, it is blocked. Initially, no rules exist, so connections are rejected. When a rule is created specifying a start and end IP address, connections from IPs in that range are allowed. This process ensures only trusted IPs can access the Azure SQL server.

Practice

1. What is the main purpose of Azure SQL firewall rules?

easy

A. To control which IP addresses can access the database

B. To encrypt data stored in the database

C. To backup the database automatically

D. To monitor database performance

Solution

1. Step 1: Understand firewall rules function

   Azure SQL firewall rules specify which IP addresses are allowed to connect to the database.

2. Step 2: Compare with other options

   Encryption, backup, and monitoring are different features not controlled by firewall rules.

3. Final Answer:

   To control which IP addresses can access the database -> Option A

4. Quick Check:

   Firewall rules = control IP access [OK]

Hint: Firewall rules control IP access, not encryption or backup [OK]

Common Mistakes:

• Confusing firewall rules with encryption settings
• Thinking firewall rules manage backups
• Assuming firewall rules monitor performance

2. Which of the following is the correct way to define a firewall rule in Azure SQL?

easy

A. Specify a username and password

B. Specify only a single IP address without a range

C. Specify a start IP and an end IP address range

D. Specify a database name and region

Solution

1. Step 1: Recall firewall rule structure

   Azure SQL firewall rules require a start IP and an end IP to define the allowed range.

2. Step 2: Eliminate incorrect options

   Single IP alone is not enough; username/password and database name/region are unrelated to firewall rules.

3. Final Answer:

   Specify a start IP and an end IP address range -> Option C

4. Quick Check:

   Firewall rule = start IP + end IP [OK]

Hint: Firewall rules need IP ranges, not usernames or database names [OK]

Common Mistakes:

• Trying to use usernames instead of IP addresses
• Defining only one IP without a range
• Confusing firewall rules with database settings

3. Given a firewall rule with start IP 192.168.1.10 and end IP 192.168.1.20, which IP address can connect?

medium

A. 192.168.1.9

B. 192.168.2.10

C. 192.168.1.21

D. 192.168.1.15

Solution

1. Step 1: Understand IP range inclusion

   The firewall rule allows IPs from 192.168.1.10 up to 192.168.1.20 inclusive.

2. Step 2: Check each IP against the range

   192.168.1.9 is below start IP, 192.168.1.15 is inside range, 192.168.1.21 and 192.168.2.10 are outside the range.

3. Final Answer:

   192.168.1.15 -> Option D

4. Quick Check:

   IP inside range = allowed [OK]

Hint: Check if IP is between start and end IP inclusive [OK]

Common Mistakes:

• Choosing IP just outside the range
• Ignoring inclusive range boundaries
• Confusing similar IP addresses

4. You created a firewall rule with start IP 10.0.0.5 and end IP 10.0.0.3. What is the problem?

medium

A. The rule allows all IPs by mistake

B. Start IP is greater than end IP, so the rule is invalid

C. The IP addresses are in different subnets

D. There is no problem; the rule is valid

Solution

1. Step 1: Check IP range order

   The start IP must be less than or equal to the end IP for a valid range.

2. Step 2: Identify invalid range

   Here, 10.0.0.5 is greater than 10.0.0.3, making the range invalid.

3. Final Answer:

   Start IP is greater than end IP, so the rule is invalid -> Option B

4. Quick Check:

   Start IP ≤ End IP for valid rule [OK]

Hint: Start IP must be less or equal to end IP [OK]

Common Mistakes:

• Ignoring IP order in the range
• Assuming different subnets cause errors
• Thinking invalid range allows all IPs

5. You want to allow access only from your office IP 203.0.113.25 and your home IP 198.51.100.10. How should you configure Azure SQL firewall rules?

hard

A. Create two separate firewall rules, each with start and end IP set to one of the IPs

B. Create one firewall rule with start IP 198.51.100.10 and end IP 203.0.113.25

C. Create one firewall rule with start IP 0.0.0.0 and end IP 255.255.255.255

D. Create a firewall rule with start IP 198.51.100.10 and end IP 198.51.100.10 only

Solution

1. Step 1: Understand IP range rules

   Firewall rules allow ranges of IPs; to allow two separate IPs, create two rules each with start and end IP the same.

2. Step 2: Evaluate options

   Create two separate firewall rules, each with start and end IP set to one of the IPs correctly creates two rules for each IP. Create one firewall rule with start IP 198.51.100.10 and end IP 203.0.113.25 creates a large range including unwanted IPs. Create one firewall rule with start IP 0.0.0.0 and end IP 255.255.255.255 allows all IPs, which is insecure. Create a firewall rule with start IP 198.51.100.10 and end IP 198.51.100.10 only allows only one IP, missing the other.

3. Final Answer:

   Create two separate firewall rules, each with start and end IP set to one of the IPs -> Option A

4. Quick Check:

   Separate IPs need separate rules [OK]

Hint: Use separate rules for separate IPs, same start and end IP [OK]

Common Mistakes:

• Trying to combine non-contiguous IPs in one rule
• Allowing all IPs by mistake
• Creating only one rule for multiple IPs