IPv6 to IPv4 Converter
Extract IPv4 addresses from IPv6 addresses. Supports 6to4, NAT64, Teredo, IPv4-mapped, and IPv4-compatible formats with RFC-compliant conversion.
Free IPv6 to IPv4 Converter: Extract IPv4 Addresses from IPv6 Online
Convert IPv6 addresses to IPv4 instantly with support for 6to4, NAT64, Teredo, IPv4-mapped, and IPv4-compatible formats. Extract embedded IPv4 addresses from dual-stack networks, tunnel addresses, and transition mechanisms with RFC-compliant conversion algorithms and detailed technical explanations.
What Is IPv6 to IPv4 Conversion (And Why You Need It)?
IPv6 to IPv4 conversion is the process of extracting embedded IPv4 addresses from IPv6 addresses that use transition mechanisms. During the global migration from IPv4 to IPv6, numerous tunneling and translation technologies were developed to maintain compatibility—6to4, NAT64, Teredo, and IPv4-mapped addresses all encode IPv4 information within their IPv6 format according to RFC 4291 (IPv6 Addressing Architecture).
These hybrid addressing schemes are critical for network administrators managing dual-stack networks, troubleshooting connectivity issues, analyzing firewall logs, and understanding traffic patterns. With 35% of internet traffic still using IPv4 as of 2024, extracting IPv4 addresses from IPv6 tunnel endpoints helps identify real client locations, detect network misconfigurations, and optimize routing policies across heterogeneous networks.
Why IPv6 to IPv4 Conversion Matters for Network Engineers:
Network Troubleshooting & Analysis
- • Identify real clients: Extract actual IPv4 from tunnel addresses
- • Debug connectivity: Trace traffic through transition mechanisms
- • Analyze logs: Convert IPv6 entries to familiar IPv4 format
- • Geolocation accuracy: IPv4 addresses have better location databases
Security & Compliance
- • Firewall configuration: Map IPv6 rules to IPv4 equivalents
- • Access control: Validate source addresses across protocols
- • Audit compliance: Track connections in mixed environments
- • Threat detection: Identify malicious IPs hiding in IPv6 tunnels
Real IPv6 to IPv4 Conversion Examples
2002:c000:0204::1 Extracts to: 192.0.2.4 (public IPv4 endpoint)::ffff:192.0.2.1 Extracts to: 192.0.2.1 (dual-stack representation)2001:0:4136:e378:8000:63bf:3fff:fdd2 Extracts server: 65.54.227.120, client: 192.0.2.4564:ff9b::192.0.2.33 Extracts to: 192.0.2.33 (NAT64 translation)How to Convert IPv6 to IPv4 in 3 Simple Steps
💡 Pro Tip: Batch IPv6 Conversion for Log Analysis
Network administrators analyzing firewall logs or server access logs can use batch mode to convert hundreds of IPv6 addresses simultaneously. This is invaluable for identifying traffic patterns, detecting anomalies, and generating reports with familiar IPv4 addresses that integrate with existing security tools and SIEM systems.
5 IPv6 to IPv4 Conversion Methods We Support
6to4 is a transition mechanism for migrating from IPv4 to IPv6 that encodes IPv4 addresses in the 2002::/16 IPv6 prefix. Defined in RFC 3056, 6to4 addresses have the format 2002:WWXX:YYZZ::/48 where WWXX:YYZZ is the hexadecimal representation of the IPv4 address W.X.Y.Z. Our tool extracts bytes 2-5 to recover the original IPv4 endpoint, critical for troubleshooting 6to4 relay configurations and validating tunnel endpoints.
NAT64 enables IPv6-only clients to access IPv4 services by embedding IPv4 addresses in the 64:ff9b::/96 prefix as specified in RFC 6052. The last 32 bits of the IPv6 address contain the IPv4 address being translated. This mechanism is widely deployed in cellular networks and IPv6-only data centers, making conversion essential for understanding traffic flows between IPv6 and IPv4 networks and configuring DNS64 resolvers.
Teredo provides IPv6 connectivity through NAT devices using UDP encapsulation over IPv4, defined in RFC 4380. Teredo addresses (2001:0000::/32) encode both the Teredo server IPv4 (bytes 4-7) and obfuscated client IPv4 (bytes 12-15, XOR'd with 0xFFFFFFFF). Our converter deobfuscates client addresses and extracts both endpoints, crucial for security monitoring since Teredo can bypass traditional firewalls. Windows systems heavily use Teredo for automatic IPv6 connectivity.
IPv4-mapped addresses (::ffff:0:0/96) represent IPv4 addresses in IPv6 format for dual-stack applications, specified in RFC 4291 Section 2.5.5.2. Format is ::ffff:w.x.y.z or ::ffff:wwxx:yyzz in hexadecimal. These addresses appear frequently in dual-stack server logs where IPv6 sockets accept both IPv4 and IPv6 connections. Converting mapped addresses helps normalize log analysis and simplify firewall rule management across protocol versions.
IPv4-compatible addresses (::/96) were early transition mechanisms, now deprecated per RFC 4291. Format is ::w.x.y.z where the last 32 bits contain the IPv4 address. While no longer recommended for new implementations, these addresses still appear in legacy systems and historical network configurations. Our tool supports conversion for compatibility and forensic analysis of older network logs.
8 Real-World IPv6 to IPv4 Conversion Scenarios
1. Network Security & Firewall Configuration
Security teams need to identify real IPv4 addresses behind IPv6 tunnel endpoints to configure firewall rules, validate access control lists, and investigate security incidents. Converting Teredo and 6to4 addresses reveals actual client locations for threat intelligence correlation. Combine with our IP lookup tool for comprehensive geolocation and reputation analysis.
2. Server Log Analysis & Traffic Monitoring
Web servers and application logs in dual-stack environments contain mixed IPv4 and IPv6 addresses. Converting IPv4-mapped addresses (::ffff:192.0.2.1) to standard IPv4 format normalizes logs for analysis tools, SIEM systems, and reporting dashboards. This simplifies detecting abuse patterns, generating visitor statistics, and integrating with existing IPv4-based analytics platforms.
3. Troubleshooting Dual-Stack Network Issues
Network engineers debugging connectivity problems in dual-stack networks need to understand how traffic flows through transition mechanisms. Extracting IPv4 from 6to4 or Teredo addresses helps verify tunnel configurations, validate relay assignments, and diagnose routing issues. Test connectivity using our subnet calculator to plan IPv6 address allocations.
4. ISP & Carrier Network Operations
Internet service providers deploying NAT64/DNS64 for IPv6-only networks must monitor translation quality and troubleshoot customer connectivity issues. Converting NAT64 addresses back to IPv4 helps validate translator configurations, debug DNS64 resolution problems, and ensure compatibility with IPv4-only services during the IPv6 transition period.
5. Geolocation & User Analytics
IPv4 geolocation databases are far more accurate and comprehensive than IPv6 databases. Extracting IPv4 from tunnel addresses provides better location data for analytics, content personalization, and fraud detection. This is critical for e-commerce, advertising platforms, and services requiring accurate user location data. Use our IP geolocation tool for detailed location analysis.
6. Compliance Auditing & Forensics
Security audits and forensic investigations require tracking all network connections. Converting IPv6 tunnel addresses to IPv4 ensures complete audit trails, helps correlate events across protocol versions, and maintains compliance with regulations requiring comprehensive connection logging. Essential for SOC 2, PCI DSS, and HIPAA compliance in mixed IPv4/IPv6 environments.
7. VPN & Remote Access Management
VPN administrators managing remote workers with Teredo connectivity need to identify actual client IPv4 addresses for access control, bandwidth management, and troubleshooting. Extracting both Teredo server and client addresses helps validate tunnel endpoints, diagnose NAT traversal issues, and optimize VPN routing policies for better performance.
8. Cloud & Data Center Migration
Organizations migrating to IPv6-only cloud environments need to maintain compatibility with IPv4 services during transition. Understanding NAT64 address mappings, validating DNS64 configurations, and troubleshooting application compatibility requires converting translated addresses back to IPv4 for integration testing and migration validation.
7 IPv6 Conversion Mistakes Network Engineers Make
1. Assuming All IPv6 Addresses Contain IPv4
Only specific IPv6 prefixes (6to4, NAT64, Teredo, mapped, compatible) contain embedded IPv4 addresses. Native IPv6 addresses (2001:db8::/32, fc00::/7) do not convert to IPv4. Always check the address prefix before attempting conversion to avoid misinterpretation of network traffic sources.
2. Forgetting Teredo Address Obfuscation
Teredo client IPv4 addresses are XOR'd with 0xFFFFFFFF for obfuscation per RFC 4380. Extracting bytes 12-15 directly without deobfuscation yields incorrect addresses. Always apply bitwise NOT operation to recover the actual client IPv4 address for accurate security analysis and troubleshooting.
3. Ignoring IPv6 Address Compression Rules
IPv6 addresses use :: compression to shorten consecutive zero blocks. When parsing, expand :: to full notation first before extracting IPv4 bytes. Failure to expand compressed addresses leads to incorrect byte offsets and invalid IPv4 extraction, especially for IPv4-mapped (::ffff:192.0.2.1) and compatible (::192.0.2.1) formats.
4. Using Deprecated IPv4-Compatible Addresses
IPv4-compatible addresses (::/96) were deprecated in 2006 per RFC 4291 due to security concerns. Modern networks should use IPv4-mapped addresses (::ffff:0:0/96) instead. Encountering IPv4-compatible addresses in production indicates legacy configurations requiring immediate security review and migration to current standards.
5. Not Validating Extracted IPv4 Addresses
After extraction, validate that IPv4 addresses are in valid ranges (not 0.0.0.0, not reserved, not multicast). Corrupted IPv6 addresses or parsing errors can produce invalid IPv4 results. Always validate using standard IPv4 format checks and reserved range verification before using addresses for security rules or routing decisions.
6. Overlooking 6to4 Relay Security Implications
6to4 addresses reveal public IPv4 endpoints but traffic flows through anycast relays (192.88.99.1). Security policies must account for relay hopping—the extracted IPv4 may not match the actual packet source seen at network boundaries. Implement comprehensive logging with our DNS lookup tool for reverse resolution.
7. Mixing Up NAT64 Prefix Variants
While 64:ff9b::/96 is the well-known NAT64 prefix per RFC 6052, networks can use custom prefixes for local NAT64 deployments. Always verify your network's NAT64 configuration before assuming standard prefix usage. Incorrect prefix assumptions lead to failed conversions and connectivity troubleshooting dead-ends.
Understanding IPv6 to IPv4 Conversion Algorithms
How 6to4 Address Extraction Works
6to4 addresses follow the format 2002:WWXX:YYZZ::/48 where WWXX:YYZZ represents the hexadecimal encoding of IPv4 address W.X.Y.Z. The conversion algorithm extracts bytes at positions 2-5 from the binary IPv6 representation. For example, 2002:c000:0204::1 contains c000:0204 (hex) = 192.0.2.4 (decimal). This mechanism enabled early IPv6 adoption by automatically tunneling IPv6 packets over existing IPv4 infrastructure without manual configuration.
Teredo Deobfuscation Process
Teredo obscures client IPv4 addresses to prevent trivial NAT type detection. The client IPv4 is stored in bytes 12-15 after XOR operation with 0xFFFFFFFF. To extract, apply bitwise NOT to each byte: if bytes are [0x3f, 0xff, 0xfd, 0xd2], the actual address is [~0x3f, ~0xff, ~0xfd, ~0x2d] = [192, 0, 2, 45]. Additionally, Teredo encodes the server IPv4 in bytes 4-7 without obfuscation for relay identification.
NAT64 Address Format Specification
NAT64 embeds IPv4 addresses in the last 32 bits of the well-known prefix 64:ff9b::/96 as defined in RFC 6052. The format is 64:ff9b::WWXX:YYZZ where WWXX:YYZZ is the IPv4 address W.X.Y.Z in hexadecimal. This allows DNS64 servers to synthesize AAAA records from A records, enabling IPv6-only clients to reach IPv4-only services transparently. Essential for mobile carriers deploying IPv6-only networks to conserve IPv4 addresses.
Frequently Asked Questions About IPv6 to IPv4 Conversion
Can all IPv6 addresses be converted to IPv4?
No, only IPv6 addresses using specific transition mechanisms contain embedded IPv4 addresses. Native IPv6 addresses (like 2001:db8::/32 documentation prefix or fc00::/7 unique local addresses) do not convert to IPv4. Our tool automatically detects compatible formats (6to4, NAT64, Teredo, IPv4-mapped, IPv4-compatible) and performs appropriate conversion based on the address prefix.
What is the difference between IPv4-mapped and IPv4-compatible addresses?
IPv4-mapped addresses (::ffff:192.0.2.1) represent IPv4 endpoints in IPv6 notation for dual-stack sockets and are actively used in modern systems per RFC 4291. IPv4-compatible addresses (::192.0.2.1) were an early transition mechanism now deprecated since 2006 due to security concerns. Always use mapped addresses for new implementations.
Why does Teredo return two IPv4 addresses?
Teredo encodes both the Teredo server IPv4 address (relay endpoint) and the client's IPv4 address (behind NAT). The server address (bytes 4-7) identifies which relay is handling the tunnel, while the obfuscated client address (bytes 12-15) reveals the actual client's public IPv4. Both are needed for complete tunnel mapping and security analysis per RFC 4380.
How accurate is automatic IPv6 address type detection?
Our auto-detection is 100% accurate for well-formed addresses using standard prefixes: 2002::/16 for 6to4, 64:ff9b::/96 for NAT64, 2001:0000::/32 for Teredo, ::ffff:0:0/96 for IPv4-mapped, and ::/96 for IPv4-compatible. Non-standard or malformed addresses require manual method selection. The tool validates address structure before conversion to prevent incorrect extractions.
Are 6to4 addresses still widely used today?
6to4 usage has declined significantly since 2015 due to reliability issues and anycast relay deprecation. However, legacy systems, embedded devices, and older network equipment still generate 6to4 traffic. Security teams must maintain conversion capability for log analysis and forensics. Modern deployments prefer native IPv6 or IPv4-as-a-Service (IPv4aaS) instead of automatic tunneling mechanisms.
How do I validate if extracted IPv4 addresses are legitimate?
After extraction, validate IPv4 addresses are not in reserved ranges (0.0.0.0/8, 127.0.0.0/8, 224.0.0.0/4 multicast, 240.0.0.0/4 experimental). Check for private ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) which may indicate NAT traversal scenarios. Use our IP lookup tool to verify geolocation, ISP assignment, and reputation for security analysis.
Can I convert multiple IPv6 addresses at once?
Yes, our batch conversion mode supports processing up to 100 IPv6 addresses simultaneously. This is ideal for analyzing firewall logs, server access logs, or network flow data. Simply paste one address per line, select the conversion method (or use auto-detect), and receive a comprehensive report with all extracted IPv4 addresses and conversion details for each input.
What RFC standards govern IPv6 to IPv4 address conversion?
Key RFCs include: RFC 3056 (6to4), RFC 6052 (NAT64), RFC 4380 (Teredo), RFC 4291 (IPv6 Addressing Architecture including mapped/compatible addresses). Our converter implements all specifications exactly as standardized for guaranteed accuracy and RFC compliance.
Advanced IPv6 Conversion Strategies for Network Engineers
Security Log Correlation
Normalize mixed IPv4/IPv6 logs by converting all transition addresses to IPv4. This enables consistent SIEM correlation, threat intelligence matching, and geographic analysis using established IPv4 databases. Essential for detecting distributed attacks spanning protocol versions.
Firewall Rule Migration
When migrating from IPv4 to IPv6, convert existing IPv4 rules to IPv4-mapped IPv6 format (::ffff:0:0/96). This maintains consistent security policies across dual-stack environments and simplifies rule management by allowing IPv6 sockets to handle both protocol families with unified access control.
Geolocation Enhancement
Extract IPv4 from tunnel addresses to leverage superior IPv4 geolocation databases. MaxMind, IP2Location, and other providers offer street-level accuracy for IPv4 but only city-level for IPv6. Critical for fraud detection, content localization, and compliance with regional data regulations.
Automated Network Mapping
Build network topology maps by extracting IPv4 endpoints from 6to4 and Teredo addresses. Identify relay servers, trace tunnel paths, and detect unauthorized transition mechanisms. Combine with our DNS lookup for reverse resolution and AS number mapping.
Performance Monitoring
Track tunnel overhead by monitoring 6to4 and Teredo conversion rates. High tunnel usage indicates IPv6 connectivity issues requiring infrastructure investment. Measure latency differences between native IPv6, tunneled traffic, and direct IPv4 to optimize routing policies and improve user experience.
Compliance Auditing
Extract and log all IPv4 endpoints from tunnel traffic for regulatory compliance. Many frameworks require comprehensive connection logs—converting IPv6 tunnels ensures no traffic escapes audit trails. Document conversion methodology for compliance officers reviewing security controls.
Essential Network & IP Tools
Complete your network analysis toolkit with our comprehensive suite of IPv4, IPv6, and DNS utilities:
Ready to Convert IPv6 to IPv4?
Extract IPv4 addresses from IPv6 tunnel endpoints instantly. Supports 6to4, NAT64, Teredo, IPv4-mapped, and IPv4-compatible formats with RFC-compliant algorithms and detailed technical explanations. 100% free, no signup required, privacy-focused.
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