diff --git a/isisd/isis_common.h b/isisd/isis_common.h
index 7a0768a..2633855 100644
--- a/isisd/isis_common.h
+++ b/isisd/isis_common.h
@@ -37,6 +37,10 @@
 #define ISIS_PASSWD_TYPE_CLEARTXT 1
 #define ISIS_PASSWD_TYPE_PRIVATE  255
   u_char type;
+  /* Authenticate SNPs? */
+#define SNP_AUTH_SEND   0x01
+#define SNP_AUTH_RECV   0x02
+  u_char snp_auth;
   u_char passwd[255];
 };