diff -uNr snort-2.2.0/src/decode.c snort-2.2.0-resets/src/decode.c
--- snort-2.2.0/src/decode.c	Thu Jun  3 15:11:05 2004
+++ snort-2.2.0-resets/src/decode.c	Wed Sep  8 16:41:38 2004
@@ -1720,6 +1720,7 @@
     u_int32_t ip_len; /* length from the start of the ip hdr to the pkt end */
     u_int32_t hlen;   /* ip header length */
     u_int16_t csum;   /* checksum */
+    Event event;      /* for checksum alerts */
 
     /* lay the IP struct over the raw data */
     p->iph = (IPHdr *) pkt;
@@ -1847,6 +1848,11 @@
         {
             p->csum_flags |= CSE_IP;
             DEBUG_WRAP(DebugMessage(DEBUG_DECODE, "Bad IP checksum\n"););
+            
+            SetEvent(&event, GENERATOR_SNORT_DECODE, DECODE_BAD_IP_CHKSUM,
+	         1, DECODE_CLASS, 3, 0);
+	    CallAlertFuncs(p, DECODE_BAD_IP_CHKSUM_STR, NULL, &event);
+
         }
 #ifdef DEBUG
         else
@@ -2105,6 +2111,7 @@
     u_int32_t hlen;            /* TCP header length */
     u_short csum;              /* checksum */
     struct pseudoheader ph;    /* pseudo header declaration */
+    Event event;               /* event for checksum alerts */
 
     if(len < 20)
     {
@@ -2197,6 +2204,11 @@
             DEBUG_WRAP(DebugMessage(DEBUG_DECODE, "Bad TCP checksum\n",
                                     "0x%x versus 0x%x\n", csum,
                                     ntohs(p->tcph->th_sum)););
+               
+            SetEvent(&event, GENERATOR_SNORT_DECODE, DECODE_BAD_TCP_CHKSUM,
+	         1, DECODE_CLASS, 3, 0);
+            CallAlertFuncs(p, DECODE_BAD_TCP_CHKSUM_STR, NULL, &event);
+
         }
         else
         {
@@ -2264,6 +2276,7 @@
     u_short csum;
     u_int16_t uhlen;
     struct pseudoheader ph;
+    Event event; /* for checksum alerts */
 
     if(len < sizeof(UDPHdr))
     {
@@ -2352,6 +2365,11 @@
         {
             p->csum_flags |= CSE_UDP;
             DEBUG_WRAP(DebugMessage(DEBUG_DECODE, "Bad UDP Checksum\n"););
+            
+            SetEvent(&event, GENERATOR_SNORT_DECODE, DECODE_BAD_UDP_CHKSUM,
+ 	         1, DECODE_CLASS, 3, 0);
+            CallAlertFuncs(p, DECODE_BAD_UDP_CHKSUM_STR, NULL, &event);
+
         }
         else
         {
@@ -2390,6 +2408,7 @@
 {
     u_int16_t csum;
     u_int16_t orig_p_caplen;
+    Event event; /* for checksum alerts */
 
     if(len < ICMP_HEADER_LEN)
     {
@@ -2503,6 +2522,11 @@
             p->csum_flags |= CSE_ICMP;
 
             DEBUG_WRAP(DebugMessage(DEBUG_DECODE, "Bad ICMP Checksum\n"););
+            
+            SetEvent(&event, GENERATOR_SNORT_DECODE, DECODE_BAD_ICMP_CHKSUM,
+                1, DECODE_CLASS, 3, 0);
+            CallAlertFuncs(p, DECODE_BAD_ICMP_CHKSUM_STR, NULL, &event);
+
         }
         else
         {
diff -uNr snort-2.2.0/src/generators.h snort-2.2.0-resets/src/generators.h
--- snort-2.2.0/src/generators.h	Thu Mar 11 16:25:52 2004
+++ snort-2.2.0-resets/src/generators.h	Wed Sep  8 16:41:38 2004
@@ -164,6 +164,12 @@
 #define     DECODE_BAD_TR_MR_LEN                  142
 #define     DECODE_BAD_TRHMR                      143
 
+#define     DECODE_BAD_IP_CHKSUM                  150
+#define     DECODE_BAD_TCP_CHKSUM                 151
+#define     DECODE_BAD_UDP_CHKSUM                 152
+#define     DECODE_BAD_ICMP_CHKSUM                153
+
+
 #define GENERATOR_SPP_SCAN2         117
 #define     SCAN_TYPE                             1
 
@@ -315,6 +321,11 @@
 #define DECODE_BAD_TR_ETHLLC_STR "(snort_decoder) WARNING: Bad Token Ring ETHLLC Header!"
 #define DECODE_BAD_TR_MR_LEN_STR "(snort_decoder) WARNING: Bad Token Ring MRLENHeader!"
 #define DECODE_BAD_TRHMR_STR "(snort_decoder) WARNING: Bad Token Ring MR Header!"
+
+#define DECODE_BAD_IP_CHKSUM_STR "(snort_decoder) WARNING: Bad IP Checksum!"
+#define DECODE_BAD_TCP_CHKSUM_STR "(snort_decoder) WARNING: Bad TCP Checksum!"
+#define DECODE_BAD_UDP_CHKSUM_STR "(snort_decoder) WARNING: Bad UDP Checksum!"
+#define DECODE_BAD_ICMP_CHKSUM_STR "(snort_decoder) WARNING: Bad ICMP Checksum!"
 
 
 #define SCAN2_PREFIX_STR "(spp_portscan2) Portscan detected from "