CGNAT & Mobile ProxiesTrust Scores Explained
How Carrier-Grade NAT affects mobile proxy detection, IP reputation, and fingerprinting. Technical guide with RFC references and real limitations.A network engineer's perspective on CGNAT implementation in mobile proxy infrastructure.
Technical Summary
CGNAT (Carrier-Grade NAT) is the standard IPv4 address sharing mechanism used by mobile carriers.Defined in RFC 6598, it allows thousands of users to share public IPv4 addresses through the 100.64.0.0/10 address space. While CGNAT can provide some advantages for proxy detection avoidance, it introduces technical complexities and doesn't eliminate all detection vectors.
Success rates vary by use case and platform, with detection systems increasingly relying on behavioral and fingerprinting techniques beyond IP reputation analysis.
Why Mobile Proxies Have Superior Trust Scores
Here's the reality: when you connect to the internet through your phone, you're not alone. Mobile carriers put thousands of regular users behind the same IP addresses. This isn't a bug - it's how mobile networks were designed to work.
Think about it this way: when Netflix sees traffic from a mobile IP, they're seeing requests from soccer moms checking their shows, teenagers on TikTok, business executives on LinkedIn, and yes, potentially someone using a mobile proxy. Everyone looks the same because they literally share the same public IP address.
The Key Difference
Unlike datacenter proxies (which come from server farms) or residential proxies (which route through home connections), mobile proxies use actual carrier infrastructure. The same towers, the same equipment, the same IP pools that your iPhone uses when you're browsing Instagram.
This fundamental architecture difference is why mobile proxies consistently achieve higher trust scores - they're indistinguishable from regular mobile users because they use identical infrastructure.
How CGNAT Creates Natural Camouflage
Shared IP Addresses
CGNAT means your mobile proxy traffic mixes with thousands of legitimate users. When Instagram sees an IP address, they can't tell if it's you, your neighbor, or a mobile proxy - everyone shares the same pool of IPs from the carrier.
Legitimate Traffic Mix
Blocking a mobile carrier IP would affect real customers - imagine if Amazon blocked T-Mobile IPs. They'd lose millions in sales. This creates natural protection for mobile proxy users.
Dynamic IP Rotation
Mobile devices naturally get new IPs as they move between cell towers or reconnect. This behavior is expected and normal, making proxy rotation patterns blend in seamlessly.
Carrier-Grade Trust
IPs from AT&T, Verizon, or T-Mobile carry inherent trust. These aren't random IPs from a hosting provider - they're from established telecom companies with millions of real users.
The Bottom Line:
CGNAT isn't just a technical detail - it's the core reason mobile proxies work so well. By sharing IPs with legitimate mobile users, your traffic becomes practically impossible to distinguish from regular mobile browsing. This isn't theory; it's how millions of mobile connections work every day.
What This Means for Your Use Case
Social Media Management
Platforms expect mobile traffic. When you manage Instagram accounts through mobile proxies, you're using the same network path as the Instagram app on phones. The platform sees normal mobile behavior - exactly what they expect.
Ad Verification
See ads as real mobile users see them. Since you're coming from the same IP pools as actual customers, advertisers can't show you different content. You get the authentic mobile experience.
Market Research
Access geo-restricted content and pricing as locals do. Mobile IPs from specific carriers in specific regions give you authentic local perspective, not the sanitized view shown to datacenter IPs.
E-commerce Operations
Many platforms flag datacenter IPs instantly but welcome mobile traffic. Whether checking prices or managing listings, mobile proxies provide the trust score needed for smooth operations.
Let's Be Honest: The Real Limitations
Mobile proxies aren't magic. While CGNAT provides significant advantages, there are real limitations you should understand:
Speed Variations
Mobile networks aren't as fast as datacenter connections. You're getting authenticity, not speed records. Expect 4G/5G speeds, which are fine for most automation but won't match fiber connections.
Behavior Still Matters
Having a mobile IP doesn't mean you can spam or act like a bot. Platforms detect patterns. If you're posting 500 times per minute, even the best mobile proxy won't save you.
Cost Considerations
Real mobile infrastructure costs more than datacenter IPs. You're paying for actual SIM cards, modems, and carrier data plans. Quality has a price.
Geographic Limitations
Mobile proxies are tied to physical locations where the modems exist. You can't get a mobile proxy from Antarctica or a tiny island nation. Coverage depends on infrastructure.
The Truth:
Mobile proxies using CGNAT provide the highest trust scores available, but they're not a license to abuse platforms. Use them responsibly, respect rate limits, and act like a human would. The technology gives you authentic mobile identity - what you do with it still matters.
CGNAT Technical Fundamentals
RFC 6598: Carrier-Grade NAT
Carrier-Grade NAT is defined in RFC 6598 as a mechanism for sharing IPv4 addresses at carrier scale. The specification allocates 100.64.0.0/10 as the dedicated address space for CGNAT operations, addressing IPv4 exhaustion while creating documented challenges with IP sharing (RFC 6269).
Technical Architecture
- Private IP allocation: 100.64.0.0/10 (CGNAT space)
- Port-based NAT translation (PAT)
- Shared public IPv4 addresses
- Session state tables for mapping
Implementation Drivers
- IPv4 address exhaustion
- CAPEX/OPEX optimization
- Regulatory compliance (logging)
- Network resource management
IPv6 Networks and 464XLAT Translation
Modern Mobile Network Architecture
Most contemporary mobile networks operate as IPv6-only with 464XLAT translation for IPv4 compatibility. This architecture means CGNAT only affects IPv4 traffic translation, while IPv6 traffic flows natively without NAT.
464XLAT Components
CLAT (Customer-side LAT)
- • IPv4-to-IPv6 translation on device
- • Uses 64:ff9b::/96 prefix
- • Enables IPv4 app compatibility
PLAT (Provider-side LAT)
- • IPv6-to-IPv4 translation at carrier
- • CGNAT for IPv4 address sharing
- • Internet gateway function
Impact on Proxy Detection
- • IPv6 connections may bypass CGNAT entirely
- • Dual-stack implementations create detection complexity
- • Translation mechanisms can introduce unique fingerprints
- • Network path analysis may reveal 464XLAT signatures
Mobile Carrier ASN Classification
Major US Carrier ASNs
| Carrier | Primary ASN | Network Name | Classification |
|---|---|---|---|
| T-Mobile | AS21928 | T-MOBILE-AS21928 | Mobile ISP |
| AT&T Mobility | AS20057 | ATT-MOBILITY-LLC-AS20057 | Mobile ISP |
| Verizon Wireless | AS22394 | VZWINTERNET | Mobile ISP |
These ASNs are typically classified as "ISP" or "Mobile" rather than "Hosting" in threat intelligence databases, which can influence initial trust scoring by security systems.
CGNAT Implementation Details
IP Address Assignment and Rotation
IP Rotation Mechanisms
Common IP Rotation Triggers
- • ✓ Airplane mode on/off (PDP context reset)
- • ✓ Network reconnection (data off/on)
- • ✓ Cross-region tower handoffs (different GGSN/PGW)
- • ✓ DHCP lease renewal (24-72hr typical)
- • ✓ Carrier pool rebalancing
When IP Usually Stays Same
- • → Local tower switching (same area)
- • → Short movements within city
- • → Signal strength changes
- • → Network congestion handoffs
- • → 3G/4G/5G band switching
DHCP and Session Management
Mobile networks assign IPs through PDP context activation. The most reliable way to rotate IP is airplane mode on/off, which forces PDP context termination and re-establishment. Moving between regions with different GGSN/PGW gateways may also trigger rotation, though local tower handoffs typically maintain the same IP.
Modern Detection Analysis
Detection Vector Analysis
CGNAT Advantages
- • ASN Classification: Mobile carrier ASNs (AS21928, AS20057, AS22394) classified as consumer ISPs
- • IP Reputation Sharing: Benefits from legitimate user traffic on shared addresses
- • Geolocation Complexity: Shared IPs make precise location tracking difficult
- • Blocking Hesitancy: Platforms avoid blocking entire carrier ranges
Persistent Detection Vectors
- • TLS Fingerprinting: JA3/JA3S signatures remain detectable regardless of IP
- • HTTP/2 Fingerprinting: Connection and frame ordering patterns
- • Behavioral Analysis: Request timing, patterns, and session management
- • Device Fingerprinting: Browser entropy and hardware characteristics
- • Application-Layer Signals: API usage patterns and sequence analysis
Performance Reality
Success rates vary significantly based on use case and platform. While mobile CGNAT IPs can reduce IP-based friction, modern detection systems employ dozens of signals beyond IP reputation. No proxy infrastructure can guarantee specific success rates or "undetectability."
Technical Limitations and Trade-offs
CGNAT Limitations
- •Port Exhaustion: High connection volumes can exhaust available port ranges on shared IPs
- •Inbound Connection Restrictions: NAT prevents direct inbound connections without port forwarding
- •Application Compatibility: Some applications and protocols don't function correctly behind CGNAT
- •Geolocation Inaccuracy: Shared IPs across regions can cause location mismatch issues
IPv6 Evolution Impact
As carriers deploy IPv6-only networks with 464XLAT, the advantages of IPv4 CGNAT may diminish. IPv6 can provide unique addresses per device, potentially changing the shared-IP dynamics that currently provide anonymity benefits.
Future Consideration: Mobile networks transitioning to IPv6-only with 464XLAT may reduce the effectiveness of current CGNAT-based anonymization strategies.
Detection Evolution
Modern anti-fraud systems employ machine learning models trained on behavioral patterns, device fingerprints, and session characteristics. While CGNAT provides IP-level anonymity, it doesn't address the majority of detection vectors used by sophisticated platforms.
CGNAT Technical Specifications
# CGNAT Implementation Specifications # Reference: RFC 6598 - IANA-Reserved IPv4 Prefix for Shared Address Space CGNAT_ADDRESS_SPACE="100.64.0.0/10" # RFC 6598 shared address space CARRIER_ASN_TMOBILE="AS21928" # T-Mobile US ASN CARRIER_ASN_ATT="AS20057" # AT&T Mobility ASN CARRIER_ASN_VERIZON="AS22394" # Verizon Wireless ASN # Technical Parameters PORT_RANGE="1024-65535" # PAT port allocation range SESSION_TIMEOUT="300-7200s" # NAT session timeout window MTU_SIZE="1420" # Typical mobile MTU DNS_CARRIER="8.8.8.8,1.1.1.1" # Carrier or public DNS # 464XLAT Configuration (IPv6-only networks) CLAT_PREFIX="64:ff9b::/96" # Well-known prefix for IPv4-embedded IPv6 PLAT_FUNCTION="stateless" # PLAT translation mode NAT64_TIMEOUT="240s" # Translation state timeout # Detection Considerations IP_SHARING_RATIO="1000-10000:1" # Users per public IP ROTATION_TRIGGER="dhcp_renewal" # Primary rotation mechanism GEOLOCATION_ACCURACY="city_level" # Typical precision limit
Practical Implementation Considerations
Engineering Perspective
CGNAT provides certain networking advantages for proxy implementations, primarily through IP address sharing and ASN classification. However, it's important to understand both the technical capabilities and limitations when architecting proxy infrastructure.
Key Technical Considerations
- CGNAT is standard mobile network architecture, not a proxy-specific technology
- IP rotation occurs through DHCP renewal, not tower switching
- Success rates depend heavily on implementation quality and use case compliance
- Modern detection relies primarily on behavioral and fingerprinting analysis
Technical FAQ
How does DHCP renewal affect IP rotation in mobile networks?
IP rotation in mobile networks primarily occurs when the PDP (Packet Data Protocol) context is reset. The most reliable trigger is airplane mode on/off, which forces complete network disconnection. Moving between distant regions may cause rotation if you connect to a different gateway (GGSN/PGW). However, local tower switches within the same area typically maintain your IP as they share the same packet core infrastructure. DHCP leases (24-72hr) also trigger rotation upon renewal.
What's the difference between CGNAT and 464XLAT?
CGNAT is IPv4 address sharing technology. 464XLAT is a translation mechanism used in IPv6-only mobile networks to provide IPv4 compatibility. 464XLAT includes CGNAT as the PLAT (Provider-side LAT) component for IPv4 internet access.
Can detection systems identify CGNAT vs. non-CGNAT traffic?
CGNAT is transparent to application-layer detection. However, network analysis might reveal CGNAT characteristics through port allocation patterns, MTU sizes, or ASN classification. The primary benefit is IP reputation sharing, not technical obscurity.
How many users typically share a CGNAT IP address?
Major US carriers typically allocate 1,000-10,000 users per public IPv4 address through CGNAT, depending on usage patterns and available address space. This ratio varies by carrier implementation and network load.
What happens to CGNAT advantages as IPv6 adoption increases?
As carriers deploy IPv6-only networks with 464XLAT, IPv6 connections may bypass CGNAT entirely, potentially providing unique addresses per device. This could reduce the anonymity benefits currently provided by IPv4 CGNAT address sharing.
Technical Assessment
CGNAT provides specific networking advantages for proxy implementations through IP address sharing and consumer ISP classification. However, modern detection systems employ sophisticated behavioral analysis and fingerprinting techniques that operate independently of IP-layer considerations.
Success rates vary significantly based on implementation quality, use case compliance, and target platform policies. While CGNAT can reduce IP-based friction, it should be viewed as one component of a comprehensive proxy architecture rather than a complete detection avoidance solution.
Engineering Summary
- CGNAT follows RFC 6598 standards and is ubiquitous in mobile networks
- IP sharing provides reputation benefits but doesn't eliminate detection vectors
- IPv6 adoption and 464XLAT may impact future CGNAT effectiveness
- Technical implementation quality remains the primary success factor
Evaluate CGNAT Mobile Infrastructure
Assess how CGNAT mobile proxy architecture might fit your technical requirements. Success varies by implementation quality and use case compliance.Technical consultation available for architecture evaluation and implementation planning.