Support a way to auth client-server connection.

I think it's necessary, such as, When using Claude Desktop to connect to a remote MCP Server, only one URL can be filled in. If identity authentication and authorization are implemented, passing information from the request parameters is a good choice.

Claude mcp config example:

{
  "mcpServers": {
    "mcp-remote-server-example": {
      "url": "http://127.0.0.1:8080/sse" 
    }
  }
}

[discard] support request params such as:

{
  "mcpServers": {
    "mcp-remote-server-example": {
      "url": "http://127.0.0.1:8080/sse?key=value" 
    }
  }
}

support 'HTTP Basic Auth' such as:

{
  "mcpServers": {
    "mcp-remote-server-example": {
      "url": "http://user:password@127.0.0.1:8080/sse" 
    }
  }
}

Comment From: lambochen

PR: https://github.com/spring-projects/spring-ai/pull/2886

Comment From: lambochen

CC: @tzolov thx

Comment From: lambochen

related mcp issue: https://github.com/modelcontextprotocol/java-sdk/issues/204 PR: https://github.com/modelcontextprotocol/java-sdk/pull/205

Comment From: quaff

Why not http://user:password@127.0.0.1:8080/sse?

Comment From: lambochen

Thank you for your comment. HTTP Basic Auth is indeed a more suitable solution for authentication scenarios

Why not http://user:password@127.0.0.1:8080/sse?

Comment From: quaff

It is indeed not possible to pass the username and password via query parameters in standard HTTP auth. Instead, you use a special URL format, like this: http://username:password@example.com/ -- this sends the credentials in the standard HTTP "Authorization" header.

See https://serverfault.com/a/371918

Comment From: lambochen

It is indeed not possible to pass the username and password via query parameters in standard HTTP auth. Instead, you use a special URL format, like this: http://username:password@example.com/ -- this sends the credentials in the standard HTTP "Authorization" header.

See https://serverfault.com/a/371918

Thank you for your related sharing, I will adjust the plan to achieve authentication more securely

Comment From: funs690

How to validate custom auth header in the sse server, such as token

client setting: WebFluxSseClientTransport transport = new WebFluxSseClientTransport(WebClient.builder().baseUrl("http://127.0.0.1:9090").defaultHeader("token", "123456"));

Comment From: funs690

This will be work

package com.zctech_ai.mcp_weather_server.config;

import lombok.extern.slf4j.Slf4j; import org.springframework.context.annotation.Configuration; import org.springframework.web.server.ServerWebExchange; import org.springframework.web.server.WebFilter; import org.springframework.web.server.WebFilterChain; import reactor.core.publisher.Mono;

@Slf4j @Configuration public class AuthConfig implements WebFilter {

/**
 * auth filter
 * @param exchange
 * @param chain
 * @return
 */
@Override
public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
    // 获取请求头
    String token = exchange.getRequest().getHeaders().getFirst("token");
    log.debug("=================================================");
    log.debug("token: " + token);
    log.debug("=================================================");
    // 可以在此做校验、拒绝请求等逻辑
    if (token == null || token.isEmpty() || !"123456".equals(token)) {
        exchange.getResponse().setStatusCode(org.springframework.http.HttpStatus.UNAUTHORIZED);
        return exchange.getResponse().setComplete();
    }
    return chain.filter(exchange);
}

}

Comment From: lambochen

rel: MCP Specification - Security and Trust & Safety

Comment From: Kehrlann

As you pointed out in the previous comment, userinfo is not passed in the URL but in the authorization header. On the server-side, this can be consumed by Spring Security to authenticate incoming requests, like so:

@Bean
SecurityWebFilterChain securityFilterChain(ServerHttpSecurity http) {
    return http
            .authorizeExchange(auth -> auth.anyExchange().authenticated())
            .httpBasic(Customizer.withDefaults())
            .build();
}

With this, the authentication stays at the "security" layer of the app and does not mix with MCP concerns.

On the client-side, you can provide authentication in the code, not in config. You would need to provide a WebClient.Builder that would be picked up by Spring AI:

@Bean
WebClient.Builder webClientBuilder() {
    return WebClient.builder()
            .defaultHeaders(h -> h.setBasicAuth("your-username", "your-password"));
}

I don't know whether Claude Desktop supports passing basic auth in the URL ; it may work but it does not seem supported.

Please note that authentication for MCP is a work in progress in the spec. The solution we seem to be converging towards is using OAuth2 for securing MCP servers.

Comment From: lambochen

MCP authorization：https://modelcontextprotocol.io/specification/2025-03-26/basic/authorization#2-6-access-token-usage

Comment From: songyuwong

When does Oauth2 authentication be supported and then different authentication connections are supported? See the tool list is different. After I customized the filter, I found that there was no pointcut to modify the list tool response. or I could do it some other way.