QUIC: fixed migration during NAT rebinding. The RFC 9000 allows a packet from known CID arrive from unknown path: These requirements regarding connection ID reuse apply only to the sending of packets, as unintentional changes in path without a change in connection ID are possible. For example, after a period of network inactivity, NAT rebinding might cause packets to be sent on a new path when the client resumes sending. Before the patch, such packets were rejected with an error in the ngx_quic_check_migration() function. Removing the check makes the separate function excessive - remaining checks are early migration check and "disable_active_migration" check. The latter is a transport parameter sent to client and it should not be used by server. The server should send "disable_active_migration" "if the endpoint does not support active connection migration" (18.2). The support status depends on nginx configuration: to have migration working with multiple workers, you need bpf helper, available on recent Linux systems. The patch does not set "disable_active_migration" automatically and leaves it for the administrator. By default, active migration is enabled. RFC 900 says that it is ok to migrate if the peer violates "disable_active_migration" flag requirements: If the peer violates this requirement, the endpoint MUST either drop the incoming packets on that path without generating a Stateless Reset OR proceed with path validation and allow the peer to migrate. Generating a Stateless Reset or closing the connection would allow third parties in the network to cause connections to close by spoofing or otherwise manipulating observed traffic. So, nginx adheres to the second option and proceeds to path validation. Note: The ngtcp2 may be used for testing both active migration and NAT rebinding: ngtcp2/client --change-local-addr=200ms --delay-stream=500ms <ip> <port> <url> ngtcp2/client --change-local-addr=200ms --delay-stream=500ms --nat-rebinding \ <ip> <port> <url>

fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
fastcgi_param  QUERY_STRING       $query_string;
fastcgi_param  REQUEST_METHOD     $request_method;
fastcgi_param  CONTENT_TYPE       $content_type;
fastcgi_param  CONTENT_LENGTH     $content_length;

fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
fastcgi_param  REQUEST_URI        $request_uri;
fastcgi_param  DOCUMENT_URI       $document_uri;
fastcgi_param  DOCUMENT_ROOT      $document_root;
fastcgi_param  SERVER_PROTOCOL    $server_protocol;
fastcgi_param  REQUEST_SCHEME     $scheme;
fastcgi_param  HTTPS              $https if_not_empty;

fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
fastcgi_param  SERVER_SOFTWARE    nginx/$nginx_version;

fastcgi_param  REMOTE_ADDR        $remote_addr;
fastcgi_param  REMOTE_PORT        $remote_port;
fastcgi_param  SERVER_ADDR        $server_addr;
fastcgi_param  SERVER_PORT        $server_port;
fastcgi_param  SERVER_NAME        $server_name;

# PHP only, required if PHP was built with --enable-force-cgi-redirect
fastcgi_param  REDIRECT_STATUS    200;