diff -Naur socat-1.7.2.1-orig/xio-ip.c socat-1.7.2.1/xio-ip.c

--- socat-1.7.2.1-orig/xio-ip.c	2011-12-06 02:45:03.000000000 -0500

+++ socat-1.7.2.1/xio-ip.c	2012-05-23 16:31:23.000000000 -0400

@@ -42,6 +42,7 @@

 const struct optdesc opt_ip_hdrincl = { "ip-hdrincl", "hdrincl",   OPT_IP_HDRINCL, GROUP_SOCK_IP, PH_PASTSOCKET, TYPE_INT, OFUNC_SOCKOPT, SOL_IP, IP_HDRINCL };

 #endif

 #ifdef IP_RECVERR

+# include <linux/errqueue.h>

 const struct optdesc opt_ip_recverr = { "ip-recverr", "recverr",   OPT_IP_RECVERR, GROUP_SOCK_IP, PH_PASTSOCKET, TYPE_INT, OFUNC_SOCKOPT, SOL_IP, IP_RECVERR };

 #endif

 #ifdef IP_MTU_DISCOVER