VPN and Proxy Glossary

GeoIP

GeoIP maps an IP address to an approximate physical location. Learn how accurate it is, why sites use it, and how a proxy changes your apparent country.

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HTTP CONNECT

HTTP CONNECT is the method that lets an HTTP proxy tunnel encrypted HTTPS traffic. Learn how it works and how s4m's HTTP proxy uses it on port 3128.

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HTTP Proxy

An HTTP proxy relays web traffic and can tunnel HTTPS with the CONNECT method. Learn how it works and how s4m runs an HTTP proxy on port 3128.

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HTTP/2

HTTP/2 speeds up the web by multiplexing many requests over one connection. Learn what it improves over HTTP/1.1 and how it affects fingerprinting.

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HTTP/3

HTTP/3 runs HTTP over QUIC and UDP to eliminate head-of-line blocking. Learn what it improves and why some HTTP proxies cannot carry it at all.

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HTTPS Proxy

An HTTPS proxy encrypts the connection between you and the proxy itself, adding privacy on untrusted networks. Learn how it differs from an HTTP proxy.

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IKEv2

IKEv2 is a fast VPN protocol paired with IPsec, prized for reconnecting quickly on mobile. Learn how it compares to the WireGuard and OpenVPN s4m offers.

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IP Reputation

IP reputation is a score sites assign an address based on its history and network. Learn what raises or lowers it and how a dedicated IP helps.

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IP Whitelisting

IP whitelisting restricts a service so only approved addresses can connect. Learn how it pairs with a dedicated IP for proxy access and security.

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IPv6 Leak

An IPv6 leak exposes your real address when IPv6 traffic bypasses an IPv4-only tunnel. Learn how it happens and how to prevent the exposure.

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ISP Proxy

An ISP proxy combines a residential ISP identity with datacenter hosting for speed. Learn how it works and how it differs from s4m's datacenter proxies.

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JA3 Fingerprint

JA3 is a widely used method of fingerprinting TLS clients from their ClientHello. Learn how the hash is built and why servers match it against clients.

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JA4 Fingerprint

JA4 is a modern, more robust successor to JA3 for fingerprinting TLS clients. Learn what it improves and why anti-bot systems are adopting it.

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Jitter

Jitter is the variation in packet delay over time, which hurts calls and streaming. Learn what causes it and how routing through a hop affects it.

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Kill Switch

A VPN kill switch restricts traffic outside the tunnel. Its scope depends on the client and policy; check DNS, IPv6 and failure behaviour.

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Latency

Latency is the round-trip delay between your device and a server, measured in milliseconds. See what causes it and how a proxy or VPN changes it.

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MTProto

MTProto is Telegram's own protocol, whose proxy mode helps users reach Telegram where it is blocked. Learn what it is and how it relates to s4m.

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MTU (Maximum Transmission Unit)

MTU is the largest packet size a link can carry, and getting it wrong causes fragmentation and slowdowns. Learn how it affects VPN tunnels like WireGuard.

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Mobile Proxy

A mobile proxy routes traffic through a cellular carrier IP, which sites rarely block because of CGNAT. Learn its trade-offs versus s4m's datacenter proxies.

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