Arp Spoofing in Axum with Jwt Tokens

Arp spoofing is a network-layer attack where an attacker sends falsified Address Resolution Protocol messages to associate their MAC address with the IP address of another host, typically the gateway. In an Axum application that relies on JWT tokens for authentication, arp spoofing can expose tokens in transit when transport-layer protections are not strictly enforced or when an attacker positions themselves on the same local network.

JWT tokens are often carried in HTTP headers (e.g., Authorization: Bearer ). If an Axum service accepts tokens over unencrypted HTTP, or if TLS is terminated inconsistently across services, arp spoofing enables an attacker on the local segment to intercept these headers. Because JWTs are self-contained and often used without additional per-request encryption, captured tokens can be replayed to impersonate users or escalate privileges. This is especially risky in environments where trust is assumed based on network location rather than strict identity verification.

The combination is risky not because Axum or JWT are inherently weak, but because arp spoofing undermines the confidentiality of token transmission. If an attacker intercepts a JWT, they can reuse it until expiration, and Axum’s routing and middleware cannot distinguish a legitimate token from a stolen one without additional network or transport protections. This makes the attack surface larger when services do not enforce strict transport security and mutual verification on every request.

To mitigate arp spoofing risks involving JWT tokens in Axum, ensure tokens are always transmitted over encrypted channels and validate their integrity and origin rigorously. Below are concrete code examples for an Axum API that uses JWT validation middleware securely.

First, enforce HTTPS in your Axum application. Use a reverse proxy or load balancer to terminate TLS, or configure Rustls directly in your server setup. Then, validate JWTs using a well-audited library such as jsonwebtoken, and ensure your token validation checks issuer, audience, and expiration on every request.

use axum::{
    async_trait,
    extract::FromRequest,
    http::{
        header::{AUTHORIZATION, HeaderMap, HeaderValue},
        Request, StatusCode,
    },
    response::IntoResponse,
    Extension,
};
use jsonwebtoken::{decode, Algorithm, DecodingKey, Validation};
use serde::{Deserialize, Serialize};
use std::net::SocketAddr;
use tower_http::fs::ServeDir;

#[derive(Debug, Serialize, Deserialize)]
struct Claims {
    sub: String,
    exp: usize,
    iss: String,
    aud: String,
}

struct JwtAuth {
    claims: Claims,
}

#[async_trait]
impl FromRequest for JwtAuth
where
    S: Send + Sync,
{
    type Rejection = (StatusCode, &'static str);

    async fn from_request(req: Request) -> Result {
        let headers = req.headers();
        let auth_header = headers.get(AUTHORIZATION)
            .ok_or((StatusCode::UNAUTHORIZED, "Missing Authorization header"))?;
        let auth_value = auth_header.to_str().map_err(|_| (StatusCode::UNAUTHORIZED, "Invalid header encoding"))?;
        if !auth_value.starts_with("Bearer ") {
            return Err((StatusCode::UNAUTHORIZED, "Invalid Authorization format"));
        }
        let token = auth_value.trim_start_matches("Bearer ").trim();
        if token.is_empty() {
            return Err((StatusCode::UNAUTHORIZED, "Empty token"));
        }

        // Use a strong decoding key and strict validation
        let decoding_key = DecodingKey::from_secret("your-256-bit-secret".as_ref());
        let mut validation = Validation::new(Algorithm::HS256);
        validation.validate_exp = true;
        validation.validate_nbf = true;
        validation.validate_iat = true;
        validation.set_issuer(&["your-trusted-issuer"]);
        validation.set_audience(&["your-trusted-audience"]);

        match decode::(token, &decoding_key, &validation) {
            Ok(token_data) => Ok(JwtAuth { claims: token_data.claims }),
            Err(_) => Err((StatusCode::UNAUTHORIZED, "Invalid token")),
        }
    }
}

async fn protected_route(
    JwtAuth { claims }: JwtAuth,
) -> impl IntoResponse {
    format!("Hello, user: {}", claims.sub)
}

#[tokio::main]
async fn main() {
    // Enforce HTTPS by using TLS in your listener; this example uses HTTP for illustration only.
    // In production, bind with TLS using Rustls or a reverse proxy.
    let app = axum::Router::new()
        .route("/protected", axum::routing::get(protected_route))
        .layer(Extension(())); // Add other extensions as needed

    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
    axum::Server::bind(&addr)
        .serve(app.into_make_service())
        .await
        .unwrap();
}