Stream: proxy_requests directive. The directive allows to drop binding between a client and existing UDP stream session after receiving a specified number of packets. First packet from the same client address and port will start a new session. Old session continues to exist and will terminate at moment defined by configuration: either after receiving the expected number of responses, or after timeout, as specified by the "proxy_responses" and/or "proxy_timeout" directives. By default, proxy_requests is zero (disabled).

--- a/src/event/ngx_event.h
+++ b/src/event/ngx_event.h
@@ -509,6 +509,7 @@ void ngx_event_recvmsg(ngx_event_t *ev);
 void ngx_udp_rbtree_insert_value(ngx_rbtree_node_t *temp,
     ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel);
 #endif
+void ngx_delete_udp_connection(void *data);
 ngx_int_t ngx_trylock_accept_mutex(ngx_cycle_t *cycle);
 ngx_int_t ngx_enable_accept_events(ngx_cycle_t *cycle);
 u_char *ngx_accept_log_error(ngx_log_t *log, u_char *buf, size_t len);