Ip4j

Ip4j is a small, simple and zero dependencies Java 11+ library for retrieving a request IP address from an HttpServletRequest. It supports various headers commonly used in web applications to forward client IP addresses.

Features

Extracts IP address from multiple sources by the following order (higher to lower priority):

• Custom user headers (optional user-provided headers)
• X-Client-IP header
• X-Forwarded-For header (if multiple comma-separated IPs found - first one is returned)
• CF-Connecting-IP header (Cloudflare)
• Fastly-Client-Ip header (Fastly CDN)
• True-Client-Ip header (Akamai, Cloudflare)
• X-Real-IP header (Nginx, FastCGI)
• X-Cluster-Client-IP header (Rackspace, Riverbed Stingray)
• X-Forwarded header (if multiple comma-separated IPs found - first one is returned)
• Forwarded-For header (if multiple comma-separated IPs found - first one is returned)
• Forwarded header (first "for" directive is used, if multiple comma-separated IPs found - first one is returned)
• appengine-user-ip header (Google App Engine)
• Cf-Pseudo-IPv4 header (Cloudflare fallback)
• request.getRemoteAddr()

Installation

Ip4j can be easily installed using JitPack, see Gradle and Maven examples below.

Gradle

Add the following to your build.gradle file:

repositories {
    mavenCentral()
    maven { url "https://jitpack.io" }
}

dependencies {
    implementation 'com.github.thewaterfall:ip4j:1.0.0'
}

Maven

Add the following to your pom.xml file:

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

<dependencies>
    <dependency>
        <groupId>com.github.thewaterfall</groupId>
        <artifactId>ip4j</artifactId>
        <version>1.0.0</version>
    </dependency>
</dependencies>

Usage

String ip = Ip4j.getIp(request); 

// With custom headers
String ip = Ip4j.getIp(request, "X-Ip");
String ip = Ip4j.getIp(request, "X-Ip", "My-Ip", "IPs");