diff --git a/usr.sbin/ppp/auth.c b/usr.sbin/ppp/auth.c
index be25ddd5d1c..d67aedaea05 100644
--- a/usr.sbin/ppp/auth.c
+++ b/usr.sbin/ppp/auth.c
@@ -17,7 +17,7 @@
  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
- * $Id: auth.c,v 1.39 1999/02/18 00:52:12 brian Exp $
+ * $Id: auth.c,v 1.40 1999/02/19 10:48:42 brian Exp $
  *
  *	TODO:
  *		o Implement check against with registered IP addresses.
@@ -327,11 +327,14 @@ auth_ReadHeader(struct authinfo *authp, struct mbuf *bp)
     bp = mbuf_Read(bp, (u_char *)&authp->in.hdr, sizeof authp->in.hdr);
     if (len >= ntohs(authp->in.hdr.length))
       return bp;
+    authp->in.hdr.length = htons(0);
     log_Printf(LogWARN, "auth_ReadHeader: Short packet (%d > %d) !\n",
                ntohs(authp->in.hdr.length), len);
-  } else
+  } else {
+    authp->in.hdr.length = htons(0);
     log_Printf(LogWARN, "auth_ReadHeader: Short packet header (%d > %d) !\n",
                sizeof authp->in.hdr, len);
+  }
 
   mbuf_Free(bp);
   return NULL;
diff --git a/usr.sbin/ppp/chap.c b/usr.sbin/ppp/chap.c
index 24127a921d3..fe76ebc216b 100644
--- a/usr.sbin/ppp/chap.c
+++ b/usr.sbin/ppp/chap.c
@@ -17,7 +17,7 @@
  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
- * $Id: chap.c,v 1.45 1999/02/18 19:11:46 brian Exp $
+ * $Id: chap.c,v 1.46 1999/02/18 19:45:06 brian Exp $
  *
  *	TODO:
  */
@@ -543,8 +543,9 @@ chap_Input(struct physical *p, struct mbuf *bp)
   int lanman;
 #endif
 
-  if ((bp = auth_ReadHeader(&chap->auth, bp)) == NULL)
-    log_Printf(LogERROR, "Chap Input: Truncated header !\n");
+  if ((bp = auth_ReadHeader(&chap->auth, bp)) == NULL &&
+      ntohs(chap->auth.in.hdr.length) == 0)
+    log_Printf(LogWARN, "Chap Input: Truncated header !\n");
   else if (chap->auth.in.hdr.code == 0 || chap->auth.in.hdr.code > MAXCHAPCODE)
     log_Printf(LogPHASE, "Chap Input: %d: Bad CHAP code !\n",
                chap->auth.in.hdr.code);
diff --git a/usr.sbin/ppp/pap.c b/usr.sbin/ppp/pap.c
index 10be5776d5e..681f90dbe31 100644
--- a/usr.sbin/ppp/pap.c
+++ b/usr.sbin/ppp/pap.c
@@ -18,7 +18,7 @@
  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
- * $Id: pap.c,v 1.30 1999/02/02 09:35:17 brian Exp $
+ * $Id: pap.c,v 1.31 1999/02/06 02:54:47 brian Exp $
  *
  *	TODO:
  */
@@ -155,8 +155,11 @@ pap_Input(struct physical *p, struct mbuf *bp)
   struct authinfo *authp = &p->dl->pap;
   u_char nlen, klen, *key;
 
-  if ((bp = auth_ReadHeader(authp, bp)) == NULL)
+  if ((bp = auth_ReadHeader(authp, bp)) == NULL &&
+      ntohs(authp->in.hdr.length) == 0) {
+    log_Printf(LogWARN, "Pap Input: Truncated header !\n");
     return;
+  }
 
   if (authp->in.hdr.code == 0 || authp->in.hdr.code > MAXPAPCODE) {
     log_Printf(LogPHASE, "Pap Input: %d: Bad PAP code !\n", authp->in.hdr.code);