Random IP Generator

The Random IP Generator creates random IP addresses within specified CIDR blocks or IP ranges, essential for network testing, load simulation, and security research. This tool supports both IPv4 and IPv6, offers unique or non-unique generation modes, and provides optional seeding for reproducible randomness. Whether you need test data for firewall rules, sample IPs for demonstrations, or random addresses for penetration testing, this generator provides flexible syntax and batch processing capabilities with clear summary statistics.

The Random IP Generator uses cryptographically secure random number generation (or seeded pseudorandom generation) to produce IP addresses uniformly distributed within specified ranges.

Syntax Formats:

• x delimiter: 192.168.1.0/24 x 5 (generate 5 random IPs)
• Space delimiter: 192.168.1.0/24 5 (generate 5 random IPs)
• [] delimiter: 192.168.1.0/24[5] (generate 5 random IPs)
• All formats are equivalent

IPv4 Examples:

• 192.168.1.0/24 x 3 → 3 random IPs from 192.168.1.0-192.168.1.255
• 10.0.0.1-10.0.0.10 5 → 5 random IPs from specified range
• 172.16.0.0/16[100] → 100 random IPs from 172.16.0.0-172.16.255.255

IPv6 Examples:

• 2001:db8::/64 x 10 → 10 random IPv6 addresses
• fe80::/10 5 → 5 random link-local addresses
• 2001:db8::1-2001:db8::100[20] → 20 random IPs in range

Unique Mode:

When "Unique" is checked, the tool ensures no duplicate IPs are generated across ALL networks:

• Tracks all generated IPs in a set
• Re-generates if duplicate is produced
• Guarantees uniqueness across multiple networks
• Example: If two networks overlap, unique mode prevents generating the same IP from both
• Warning: May be slow for very small ranges with large counts

Non-Unique Mode:

When unchecked, duplicates are allowed:

• Faster generation, no uniqueness tracking
• Useful for load testing scenarios where duplicates simulate real traffic
• May produce duplicate IPs within same network or across networks

Seeded Randomness:

Providing a seed makes generation reproducible:

• Same seed + same inputs = same random IPs
• Useful for testing, debugging, and demonstrations
• Example: Seed "test123" always produces same sequence
• Leave seed empty for true randomness (cryptographically secure)

Generation Algorithm:

1. Parse network/range to determine address space size
2. For each requested IP:
   • Generate random index within [0, size-1]
   • Calculate IP at that index (similar to Nth IP calculator)
   • If unique mode: check against existing set, regenerate if duplicate
   • Add to results
3. Return generated IPs with summary statistics

Default Count Behavior:

• If line has explicit count (x, space, []), use that count
• If line has only network, use Default Count field value
• Example: Default Count = 5, line "192.168.1.0/24" → generates 5 IPs
• Example: Line "10.0.0.0/24 x 10" ignores Default Count, generates 10 IPs

Performance Considerations:

• Large IPv6 subnets: Instant generation, virtually no collision risk
• Small ranges with unique mode: May be slow if count approaches range size
• Example: Generating 250 unique IPs from /24 (256 total) requires many retries
• Best practice: Use non-unique mode for large counts from small ranges

Security and Testing Use Cases:

• Firewall rule testing: Generate random sources to verify ACLs
• IDS/IPS testing: Create diverse traffic patterns
• Load balancer testing: Simulate distributed clients
• Log anonymization: Replace real IPs with random ones
• IMPORTANT: Only use for authorized testing, never for malicious purposes

Summary Statistics:

• Total IPs Generated: Sum of all requested counts
• Unique IPs Generated: Count of distinct IPs (may be less than total if duplicates occur)
• In unique mode: both numbers should match
• In non-unique mode: unique count may be less than total

Practical Examples:

• Testing firewall rule for 10.0.0.0/24: Generate 50 random IPs to verify allow/deny
• Simulating 100 distributed clients: Generate 100 unique IPs from large range
• Load testing with 1000 connections: Generate 1000 IPs (non-unique, faster)
• Creating test database: Generate 10,000 unique IPv6 addresses for records