Package org.mockserver.netty.proxy

Class MockServerIpTransparentHelper

java.lang.Object
org.mockserver.netty.proxy.MockServerIpTransparentHelper
public final class MockServerIpTransparentHelper extends Object
Wires the IP_TRANSPARENT socket option on the server bootstrap when TPROXY mode is enabled.

The IP_TRANSPARENT socket option (Linux SOL_IP = 0, IP_TRANSPARENT = 19) allows the listener socket to accept connections destined for any IP address, not just the local addresses of the host. This is required for the TPROXY iptables target to work: the kernel redirects traffic to the listener socket while preserving the original destination as the socket's local address.

On Netty epoll transport, this is exposed as io.netty.channel.epoll.EpollChannelOption.IP_TRANSPARENT. On NIO transport or non-Linux platforms, this method is a no-op (logs a debug message).

Usage: call applyIfEnabled(ServerBootstrap, Configuration) after constructing the ServerBootstrap and before binding. This is idempotent.

Requires: CAP_NET_ADMIN on the process. Without it, the setsockopt(IP_TRANSPARENT) call will fail with EPERM and the Netty channel bind will fail. This is expected in non-TPROXY deployments.

See Also:

  • Method Details

    • applyIfEnabled

      public static boolean applyIfEnabled(io.netty.bootstrap.ServerBootstrap bootstrap, Configuration configuration)
      Applies the IP_TRANSPARENT channel option to the server bootstrap if TPROXY mode is enabled in configuration and the epoll transport is available.
      Parameters:
      bootstrap - the server bootstrap to configure
      configuration - the MockServer configuration
      Returns:
      true if the option was applied, false otherwise