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Jan Wagner 2006-11-23 13:37:04 +00:00
parent 9ec2123432
commit bbd2ffd600
8 changed files with 246 additions and 99 deletions
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18
README
View file

@ -1,4 +1,4 @@
DNS FLood Detector 1.10
DNS FLood Detector 1.12
Dennis Opacki
dopacki@adotout.com
@ -17,6 +17,9 @@ incoming dns queries to a nameserver. The tool may be run in one of two
modes, either daemon mode or "bindsnap" mode. In daemon mode, the tool
will alarm via syslog. In bindsnap mode, the user is able to get
near-real-time stats on usage to aid in more detailed troubleshooting.
By default, it will count dns queries directed to any address in the same
network as the primary IP address on the interface being watched; the -A,
-M, and -Q options can be used to modify this behaviour.
How do I build it?
@ -52,22 +55,23 @@ Usage: ./dns_flood_detector [OPTION]
-w N calculate stats every N seconds
-x N create N buckets
-m N mark total query rate every N seconds
-A addr filter for specific address
-M mask netmask for filter (in conjunction with -A)
-Q don't filter by local interface address
-b run in foreground in bindsnap mode
-d run in background in daemon mode
-D dump dns packets (implies -b)
-v verbose output - use again for more verbosity
-h display this usage information
Sample Output:
dopacki:~$ sudo ./dns_flood_detector -v -v -b -t10
[15:14:56] source [192.168.1.45] - 0 qps tcp : 24 qps udp [8 qps A] [16
qps PTR]
[15:14:56] source [192.168.1.45] - 0 qps tcp : 24 qps udp [8 qps A] [16 qps PTR]
[15:14:56] source [10.0.24.2] - 0 qps tcp : 15 qps udp [15 qps A]
[15:15:06] source [192.168.1.45] - 0 qps tcp : 24 qps udp [8 qps A] [16
qps PTR]
[15:15:06] source [192.168.1.45] - 0 qps tcp : 24 qps udp [8 qps A] [16 qps PTR]
[15:15:06] source [10.0.24.2] - 0 qps tcp : 15 qps udp [14 qps A]
[15:15:16] source [192.168.1.45] - 0 qps tcp : 23 qps udp [7 qps A] [15
qps PTR]
[15:15:16] source [192.168.1.45] - 0 qps tcp : 23 qps udp [7 qps A] [15 qps PTR]
What if I have questions?

302
dns_flood_detector.c
View file

@ -22,8 +22,13 @@
(default 50)
-m n mark overall query rate every n seconds
(default disabled)
-A addr filter for specific address
-M mask netmask for filter (in conjunction with -A)
-Q monitor any addresses (default is to filter only for
primary addresses on chosen interface)
-b run in foreground in "bindsnap" mode
-d run in background in "daemon" mode
-D dump dns packets (implies -b)
-v detailed information (use twice for more detail)
-h usage info
@ -72,6 +77,22 @@
10/22/2003 - Added 'mark status' option via '-m' - <dopacki@adotout.com>
10/23/2003 - Code cleanup in verbose syslogging - <dopacki@adotout.com>
--- new in v1.11 ---
06/14/2005 - added A6, AAAA, ANY qtypes - <jwestfall@surrealistic.net>
examine all packets with >= 1 qdcount - <jwestfall@surrealistic.net>
stop processing packet if invalid dns char - <jwestfall@surrealistic.net>
fix tcp parsing - <jwestfall@surrealistic.net>
add option_D to dump packets - <jwestfall@surrealistic.net>
--- new in v1.12 ---
03/03/2006 - added address filtering options - <erikm@buh.org>
fix segfault using argv[0] after getopt - <erikm@buh.org>
fix rounding from float/int conversions, use unsigned more consistently - <erikm@buh.org>
clean up to work with -Wall - <erikm@buh.org>
show fractional qps rates for totals - <erikm@buh.org>
store addresses raw, instead of as text (speedup/reduce memory usage) - <erikm@buh.org>
fix crash on long syslog messages - <jwestfall@surrealistic.net>
********************************************************************************/
#include <pcap.h>
@ -84,6 +105,7 @@
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <arpa/inet.h>
#ifdef __bsdi__
#include <net/if_ethernet.h>
#else
@ -99,6 +121,8 @@
#include <math.h>
#include <signal.h>
#include <syslog.h>
#include <string.h>
#include <sys/stat.h>
#include "dns_flood_detector.h"
// global variables and their defaults
@ -111,10 +135,17 @@ int option_x = 50;
int option_m = 0;
int option_b = 0;
int option_d = 0;
int option_D = 0;
int option_v = 0;
int option_h = 0;
int option_Q = 0;
int option_A = 0;
int option_M = 0;
int totals = 0;
char VERSION[] = "1.10";
char VERSION[] = "1.12";
// 255.255.255.255 is invalid as a src IP address; we'll use it to mark empty buckets
#define BCAST 0xffFFffFF
// this is our statistics thread
void *run_stats () {
@ -131,27 +162,28 @@ void *run_stats () {
// calculate the running average within each bucket
int calculate_averages() {
u_int i,j,delta,cursize,newsize,qps;
u_int i,j,delta,cursize,qps;
int newsize;
float qpsf;
char st_time[10];
time_t now = time(0);
u_int types[] = {1,2,5,6,12,15,252,0};
u_char *type;
u_char *target;
char *names[] = {"A","NS","CNAME","SOA","PTR","MX","AXFR",""};
u_int types[] = {1,2,5,6,12,15,28,38,252,255,0};
char *target;
char *names[] = {"A","NS","CNAME","SOA","PTR","MX","AAAA","A6","AXFR","ANY",""};
struct tm *raw_time = localtime(&now);
snprintf(st_time, 9, "%02d:%02d:%02d",raw_time->tm_hour,raw_time->tm_min,raw_time->tm_sec);
for (i=0; i<option_x; i++) {
// only process valid buckets
if ( bb[i]->ip_addr != NULL ) {
if ( bb[i]->ip_addr.s_addr != BCAST) {
delta = now - bb[i]->first_packet;
// let's try to avoid a divide-by-zero, shall we?
if (delta > 1 ) {
// round our average and save it in the bucket
bb[i]->qps = (int)ceil( (float)((((float)bb[i]->tcp_count) + bb[i]->udp_count) / delta));
bb[i]->qps = (u_int)ceil( (bb[i]->tcp_count + bb[i]->udp_count) / (float)delta);
// handle threshold crossing
if ( bb[i]->qps > option_t ) {
@ -160,18 +192,19 @@ int calculate_averages() {
// display detail to either syslog or stdout
if ( option_b ) {
if ( ! option_v ) {
printf("[%s] source [%s] - %d qps\n",st_time,bb[i]->ip_addr,bb[i]->qps);
printf("[%s] source [%s] - %u qps\n",st_time,inet_ntoa(bb[i]->ip_addr),bb[i]->qps);
fflush(stdout);
}
else {
printf("[%s] source [%s] - %d qps tcp : %d qps udp ",st_time,bb[i]->ip_addr,
(int)ceil( (float)(bb[i]->tcp_count/delta)),
(int)ceil( (float)(bb[i]->udp_count/delta))
printf("[%s] source [%s] - %u qps tcp : %u qps udp ",st_time,inet_ntoa(bb[i]->ip_addr),
(u_int)ceil( ((float)bb[i]->tcp_count/delta)),
(u_int)ceil( ((float)bb[i]->udp_count/delta))
);
if ( option_v >1 ) {
for (j=0;types[j];j++) {
if ((int)ceil((float)(bb[i]->qstats[types[j]]/delta))){
printf("[%d qps %s] ",(int)ceil((float)(bb[i]->qstats[types[j]]/delta)),names[j]);
qps = (u_int)ceil((float)bb[i]->qstats[types[j]]/delta);
if (qps){
printf("[%u qps %s] ",qps,names[j]);
}
}
}
@ -185,21 +218,21 @@ int calculate_averages() {
// display appropriate level of detail via syslog
if ( ! option_v ) {
syslog(LOG_NOTICE,"source [%s] - %d qps\n",bb[i]->ip_addr,bb[i]->qps);
syslog(LOG_NOTICE,"source [%s] - %u qps\n",inet_ntoa(bb[i]->ip_addr),bb[i]->qps);
}
else if (option_v > 1) {
target = (char *)malloc(sizeof(char)*MAXSYSLOG);
newsize = MAXSYSLOG;
cursize = snprintf(target,newsize,"source [%s] - %d tcp qps : %d udp qps ",bb[i]->ip_addr,
(int)ceil( (float)(bb[i]->tcp_count/delta)),
(int)ceil( (float)(bb[i]->udp_count/delta))
cursize = snprintf(target,newsize,"source [%s] - %u tcp qps : %u udp qps ",inet_ntoa(bb[i]->ip_addr),
(u_int)ceil( ((float)bb[i]->tcp_count/delta)),
(u_int)ceil( ((float)bb[i]->udp_count/delta))
);
newsize-=cursize;
for (j=0;types[j];j++ ) {
qps = (u_int)ceil((float)(bb[i]->qstats[types[j]]/delta));
qps = (u_int)ceil(((float)bb[i]->qstats[types[j]]/delta));
if ( ( qps > 0) && ( newsize > 1 ) ) {
cursize = snprintf(target+(MAXSYSLOG-newsize),newsize,"[%d qps %s] ",qps,names[j]);
cursize = snprintf(target+(MAXSYSLOG-newsize),newsize,"[%u qps %s] ",qps,names[j]);
newsize-=cursize;
}
}
@ -210,9 +243,9 @@ int calculate_averages() {
free(target);
}
else {
syslog(LOG_NOTICE,"source [%s] - %d tcp qps - %d udp qps\n",bb[i]->ip_addr,
(int)ceil( (float)(bb[i]->tcp_count/delta)),
(int)ceil( (float)(bb[i]->udp_count/delta))
syslog(LOG_NOTICE,"source [%s] - %u tcp qps - %u udp qps\n",inet_ntoa(bb[i]->ip_addr),
(u_int)ceil( ((float)bb[i]->tcp_count/delta)),
(u_int)ceil( ((float)bb[i]->udp_count/delta))
);
}
@ -226,17 +259,17 @@ int calculate_averages() {
}
// 'mark stats' if required and it is time
delta = now - bb[totals]->first_packet;
delta = (u_int)(now - bb[totals]->first_packet);
if ( (option_m > 0)&&(delta > 1)&&(delta >= option_m) ) {
// handle bindsnap mode
if (option_b) {
printf("[%s] totals - %d qps tcp : %d qps udp ",st_time,(int)ceil( (float)(bb[totals]->tcp_count/delta)),(int)ceil( (float)(bb[totals]->udp_count/delta)));
printf("[%s] totals - %3.2f qps tcp : %3.2f qps udp ",st_time, ((float)bb[totals]->tcp_count/delta),((float)bb[totals]->udp_count/delta));
if (option_v) {
for (j=0;types[j];j++) {
qps = (u_int)ceil((float)(bb[totals]->qstats[types[j]]/delta));
if (qps){
printf("[%d qps %s] ",qps,names[j]);
qpsf = ((float)bb[totals]->qstats[types[j]]/delta);
if (qpsf > 0){
printf("[%3.2f qps %s] ",qpsf,names[j]);
}
}
}
@ -248,16 +281,16 @@ int calculate_averages() {
if (option_v) {
target = (char *)malloc(sizeof(char)*MAXSYSLOG);
newsize = MAXSYSLOG;
cursize = snprintf(target,newsize,"[totals] - %d tcp qps : %d udp qps ",
(int)ceil( (float)(bb[totals]->tcp_count/delta)),
(int)ceil( (float)(bb[totals]->udp_count/delta))
cursize = snprintf(target,newsize,"[totals] - %3.2f tcp qps : %3.2f udp qps ",
((float)bb[totals]->tcp_count/delta),
((float)bb[totals]->udp_count/delta)
);
newsize-=cursize;
for (j=0;types[j];j++ ) {
qps = (u_int)ceil((float)(bb[totals]->qstats[types[j]]/delta));
if ( ( qps > 0) && ( newsize > 1 ) ) {
cursize = snprintf(target+(MAXSYSLOG-newsize),newsize,"[%d qps %s] ",qps,names[j]);
qpsf = ((float)bb[totals]->qstats[types[j]]/delta);
if ( ( qpsf > 0) && ( newsize > 1 ) ) {
cursize = snprintf(target+(MAXSYSLOG-newsize),newsize,"[%3.2f qps %s] ",qpsf,names[j]);
newsize-=cursize;
}
}
@ -268,9 +301,9 @@ int calculate_averages() {
free(target);
}
else {
syslog(LOG_NOTICE,"[totals] - %d tcp qps : %d udp qps\n",
(int)ceil( (float)(bb[totals]->tcp_count/delta)),
(int)ceil( (float)(bb[totals]->udp_count/delta))
syslog(LOG_NOTICE,"[totals] - %3.2f tcp qps : %3.2f udp qps\n",
((float)bb[totals]->tcp_count/delta),
((float)bb[totals]->udp_count/delta)
);
}
}
@ -280,6 +313,17 @@ int calculate_averages() {
return 1;
}
int valid_dns_char(char c) {
if((c >= '0' && c <= '9')
|| (c >= 'a' && c <= 'z')
|| (c >= 'A' && c <= 'Z')
|| (c == '-')
|| (c == '_')) // is valid for SRV records.
return 1;
return 0;
}
// purge and initialize all buckets
void init_buckets() {
u_int i;
@ -289,7 +333,6 @@ void init_buckets() {
if ( ( bb = malloc( sizeof(struct bucket *) * (option_x+1)) ) == NULL ) malloc_fail("bb", sizeof(struct bucket *) * (option_x+1));
for (i=0; i <=option_x; i++ ) {
if ( ( bb[i] = (struct bucket *)malloc( sizeof(struct bucket) ) ) == NULL) malloc_fail("bb[i]", sizeof(struct bucket) );
bb[i]->ip_addr=NULL;
scour_bucket(i);
}
pthread_mutex_unlock(&stats_lock);
@ -299,10 +342,7 @@ void init_buckets() {
int scour_bucket( int i ) {
int j;
if ( bb[i]->ip_addr != NULL ) {
free ( bb[i]->ip_addr );
}
bb[i]->ip_addr=NULL;
bb[i]->ip_addr.s_addr=BCAST;
bb[i]->tcp_count=0;
bb[i]->udp_count=0;
bb[i]->qps=0;
@ -317,7 +357,7 @@ int scour_bucket( int i ) {
}
// add a packet to a bucket
int add_to_bucket ( char * ip_src, int ip_proto, int num_queries, u_int8_t qtype) {
int add_to_bucket ( struct in_addr *ip_src, int ip_proto, int num_queries, u_int8_t qtype) {
int bucket = 0;
// get the bucket to put packet in
@ -343,14 +383,14 @@ int add_to_bucket ( char * ip_src, int ip_proto, int num_queries, u_int8_t qtype
}
// figure out where to put this packet
int find_bucket(char *ip_src) {
int find_bucket(struct in_addr *ip_src) {
int i, bucket=0;
time_t oldest=0;
// look for an existing bucket for this IP
for (i=0; i< option_x; i++ ){
// ip field of bucket is not null and seems to match the ip we are checking
if ((bb[i]->ip_addr != NULL)&&(strncmp(bb[i]->ip_addr, ip_src, strlen(bb[i]->ip_addr))==0)) {
// ip field of bucket seems to match the ip we are checking
if (bb[i]->ip_addr.s_addr == ip_src->s_addr) {
return i;
}
}
@ -359,14 +399,20 @@ int find_bucket(char *ip_src) {
for (i=0; i< option_x; i++ ) {
// found an unused one - clean it, init it, and return it
if ( bb[i]->ip_addr == NULL ) {
if ( bb[i]->ip_addr.s_addr == BCAST ) {
scour_bucket(i);
if ( ( bb[i]->ip_addr = (char *)strdup(ip_src) ) == NULL) malloc_fail("bb[i]->ip_addr", strlen(ip_src) );
bb[i]->ip_addr.s_addr = ip_src->s_addr;
return i;
}
// find the most stagnant bucket in case we need it
// avoids another loop through the buckets
// TODO - should we autoflush buckets after some idle time,
// or after alarming? fixes the case where
// alarms are unlikely to reappear even if a client
// resumes flooding if there isn't bucket contention
// churning them out and resetting the timer for the rate
// calculation...
if ( ( bb[i]->last_packet != 0 ) && ((oldest==0)||( bb[i]->last_packet < oldest))) {
oldest = bb[i]->last_packet;
bucket = i;
@ -376,7 +422,7 @@ int find_bucket(char *ip_src) {
// use the most stagnant bucket since all are in use
// clean it, init it, and return it
scour_bucket(bucket);
if ( ( bb[bucket]->ip_addr = (char *)strdup(ip_src) ) == NULL) malloc_fail("bb[bucket]->ip_addr", strlen(ip_src) );
bb[i]->ip_addr.s_addr = ip_src->s_addr;
return bucket;
}
@ -391,10 +437,10 @@ void handle_IP(u_char *args, const struct pcap_pkthdr* pkthdr,const u_char* pack
u_int caplen = pkthdr->caplen;
u_int hlen,off,version;
unsigned char dname[NS_MAXDNAME]="";
char *ip_src;
struct in_addr ip_src;
unsigned char *data;
u_int i,len,dpos;
u_int8_t qtype,qclass,tlen;
u_int len,dpos;
u_int8_t qtype,tlen;
// skip the ethernet header
length -= sizeof(struct ether_header);
@ -431,8 +477,8 @@ void handle_IP(u_char *args, const struct pcap_pkthdr* pkthdr,const u_char* pack
off = ntohs(ip->ip_off);
if((off & 0x1fff) == 0 ) {
// get the source ip as a string (probably more efficient to use decimal)
ip_src = (char *)inet_ntoa(ip->ip_src);
// get the source ip
ip_src.s_addr = ip->ip_src.s_addr;
// process udp packets
if ( ip->ip_p == 17 ) {
@ -457,13 +503,14 @@ void handle_IP(u_char *args, const struct pcap_pkthdr* pkthdr,const u_char* pack
if (! tcp->th_flags & TH_PUSH) return;
// try to make sure it is safe to cast packet into dns structure
if ( (sizeof(struct my_dns)+sizeof(struct ether_header)+sizeof(struct ip)+(tcp->th_off * sizeof(u_int32_t))) >= caplen ) {
if ( (sizeof(struct my_dns)+sizeof(struct ether_header)+sizeof(struct ip)+(tcp->th_off * sizeof(u_int32_t)) + sizeof(u_int16_t)) >= caplen ) {
return;
}
else {
// populate dns header
dns = (struct my_dns *) ( (char *) packet + sizeof(struct ether_header)+ sizeof (struct ip) + (tcp->th_off * sizeof(u_int32_t)));
data = (char *) packet + sizeof(struct ether_header) + sizeof (struct ip) + (tcp->th_off * sizeof(u_int32_t)) + sizeof(struct my_dns);
// tcp dns lookups also include a 16bit length field = dns header + data.
dns = (struct my_dns *) ( (char *) packet + sizeof(struct ether_header)+ sizeof (struct ip) + (tcp->th_off * sizeof(u_int32_t) + sizeof(u_int16_t)));
data = (char *) packet + sizeof(struct ether_header) + sizeof (struct ip) + (tcp->th_off * sizeof(u_int32_t)) + sizeof(struct my_dns) + sizeof(u_int16_t);
}
}
@ -477,8 +524,8 @@ void handle_IP(u_char *args, const struct pcap_pkthdr* pkthdr,const u_char* pack
return;
}
// ignore seemingly bogus queries with multiple flags set
if ((ntohs(dns->dns_qdcount)>0)+(ntohs(dns->dns_ancount)>0)+(ntohs(dns->dns_nscount)>0)+(ntohs(dns->dns_arcount)>0)>1 ) {
// ignore packets with no questions
if (ntohs(dns->dns_qdcount) == 0) {
return;
}
@ -488,6 +535,10 @@ void handle_IP(u_char *args, const struct pcap_pkthdr* pkthdr,const u_char* pack
if (!tlen) tlen=*data;
for (;(tlen&&((void *)data<((void *)packet+caplen-1)));tlen--){
data++;
// bail on an invalid dns char
if(!valid_dns_char(*data)) {
return;
}
if (dpos<NS_MAXDNAME) dname[dpos++] = *data;
}
if (dpos<NS_MAXDNAME) dname[dpos++] = '.';
@ -503,9 +554,14 @@ void handle_IP(u_char *args, const struct pcap_pkthdr* pkthdr,const u_char* pack
return;
}
if( option_D ) {
printf("src: %-15s proto: %s qtype: 0x%02x domain: %s\n", (inet_ntoa(ip_src)),
(ip->ip_p == 17 ? "udp" : "tcp"), qtype, dname);
}
// add packet to bucket array
if (ntohs(dns->dns_qdcount)&&qtype) {
add_to_bucket( ip_src, ip->ip_p, 1, qtype );
add_to_bucket( &ip_src, ip->ip_p, 1, qtype );
}
}
return;
@ -525,15 +581,16 @@ int main(int argc,char **argv){
char *dst_addr = NULL;
char *dst_mask = NULL;
struct sigaction sa;
struct in_addr addr;
struct in_addr addr,tmpaddr;
u_int f_size;
char *args = NULL;
char *name = NULL;
u_int c = 0;
if ( ( name = (char *)strdup(argv[0]) ) == NULL) malloc_fail("name", strlen(argv[0]) );
// loop through command line options and get options
while(1) {
int option_index = 0;
c = getopt(argc, argv,"i:t:a:w:x:m:bdvh");
c = getopt(argc, argv,"i:t:a:w:x:m:A:M:QbdDvh");
if (c==-1) break;
switch(c) {
@ -579,12 +636,40 @@ int main(int argc,char **argv){
}
}
break;
case 'M':
if (optarg && (dst_mask == NULL) ) {
if ( inet_aton(optarg, &tmpaddr) ) {
if ( ( dst_mask = (char *)strdup(optarg) ) == NULL) malloc_fail("filter mask", strlen(optarg) );
option_M=1;
} else {
fprintf(stderr,"Invalid filter mask \"%s\"\n",optarg);
option_h = 1;
}
}
break;
case 'A':
if (optarg && (dst_addr == NULL) ) {
if ( inet_aton(optarg, &tmpaddr) ) {
if ( ( dst_addr = (char *)strdup(optarg) ) == NULL) malloc_fail("dest filter", strlen(optarg) );
option_A=1;
} else {
fprintf(stderr,"Invalid filter address \"%s\"\n",optarg);
option_h = 1;
}
}
break;
case 'Q':
option_Q = 1;
break;
case 'b':
option_b = 1;
break;
case 'd':
option_d = 1;
break;
case 'D':
option_D = 1;
break;
case 'v':
option_v++;
break;
@ -599,25 +684,45 @@ int main(int argc,char **argv){
if (optind<argc) option_h = 1;
if (option_h) {
fprintf(stderr,"dns_flood_detector, version %s\n",VERSION);
fprintf(stderr,"Usage: %s [OPTION]\n\n",argv[0]);
fprintf(stderr,"Usage: %s [OPTION]\n\n",name);
fprintf(stderr,"-i IFNAME specify device name to listen on\n");
fprintf(stderr,"-t N alarm at >N queries per second\n");
fprintf(stderr,"-a N reset alarm after N seconds\n");
fprintf(stderr,"-w N calculate stats every N seconds\n");
fprintf(stderr,"-x N create N buckets\n");
fprintf(stderr,"-m N report overall stats every N seconds\n");
fprintf(stderr,"-A addr filter for specific address\n");
fprintf(stderr,"-M mask netmask for filter (in conjunction with -A)\n");
fprintf(stderr,"-Q don't filter by local interface address\n");
fprintf(stderr,"-b run in foreground in bindsnap mode\n");
fprintf(stderr,"-d run in background in daemon mode\n");
fprintf(stderr,"-D dump dns packets (implies -b)\n");
fprintf(stderr,"-v verbose output - use again for more verbosity\n");
fprintf(stderr,"-h display this usage information\n");
exit(1);
}
if ( ( ! option_d ) && ( ! option_b ) ) {
fprintf(stderr,"%s couldn't start\n",argv[0]);
fprintf(stderr,"You must specify either either -d (daemon) or -b (bindsnap)\n");
// if dumping packets, force option_b and disable option_d
if( option_D ) {
if( ! option_b )
option_b = 1;
if( option_d )
option_d = 0;
}
if ( ( option_Q ) && ( option_A ) ) {
fprintf(stderr,"%s couldn't start\n",name);
fprintf(stderr,"You can't specify both -A (address filter) and -Q (no filter)\n");
exit(1);
}
if ( ( ! option_d ) && ( ! option_b ) ) {
fprintf(stderr,"%s couldn't start\n",name);
fprintf(stderr,"You must specify either -d (daemon) or -b (bindsnap)\n");
exit(1);
}
free(name);
// set up for daemonized operation unless running in bindsnap mode
if ( ! option_b ) {
openlog("dns_flood_detector",LOG_PID|LOG_CONS,LOG_DAEMON);
@ -641,27 +746,48 @@ int main(int argc,char **argv){
exit(1);
}
// get network address and netmask for device
pcap_lookupnet(dev,&netp,&maskp,errbuf);
// set up filter with local network
addr.s_addr = (unsigned long int)netp;
if ( ( dst_addr = (char *)malloc( strlen((char *)inet_ntoa(addr))+1) ) == NULL ) malloc_fail("dest_addr", strlen((char *)inet_ntoa(addr))+1 );
strncpy(dst_addr,(char*)inet_ntoa(addr),strlen((char *)inet_ntoa(addr)));
dst_addr[strlen((char *)inet_ntoa(addr))]='\0';
addr.s_addr = (unsigned long int)maskp;
if ( ( dst_mask = (char *)malloc( strlen((char *)inet_ntoa(addr))+1) ) == NULL ) malloc_fail("dest_mask", strlen((char *)inet_ntoa(addr))+1 );
strncpy(dst_mask,(char*)inet_ntoa(addr),strlen((char *)inet_ntoa(addr)));
dst_mask[strlen((char *)inet_ntoa(addr))]='\0';
f_size = strlen("port 53 and dst net mask ")+ strlen(dst_mask)+ strlen(dst_addr);
if ( ( filter = (char *) malloc ( f_size+1) ) == NULL ) malloc_fail( "filter", f_size+1 );
snprintf( filter, f_size, "port 53 and dst net %s mask %s", dst_addr, dst_mask);
free (dst_mask);
free (dst_addr);
/* restrict to queries to primary local address? */
if (option_Q) {
f_size = strlen("port 53 ");
if ( ( filter = (char *) malloc ( f_size+1) ) == NULL ) malloc_fail( "filter", f_size+1 );
snprintf( filter, f_size, "port 53");
} else {
if (! option_A) {
// get network address and netmask for device
pcap_lookupnet(dev,&netp,&maskp,errbuf);
// set up filter with local network
addr.s_addr = (unsigned long int)netp;
if ( ( dst_addr = (char *)malloc( strlen((char *)inet_ntoa(addr))+1) ) == NULL ) malloc_fail("dest_addr", strlen((char *)inet_ntoa(addr))+1 );
strncpy(dst_addr,(char*)inet_ntoa(addr),strlen((char *)inet_ntoa(addr)));
dst_addr[strlen((char *)inet_ntoa(addr))]='\0';
addr.s_addr = (unsigned long int)maskp;
if (!option_M) {
if ( ( dst_mask = (char *)malloc( strlen((char *)inet_ntoa(addr))+1) ) == NULL ) malloc_fail("dest_mask", strlen((char *)inet_ntoa(addr))+1 );
strncpy(dst_mask,(char*)inet_ntoa(addr),strlen((char *)inet_ntoa(addr)));
dst_mask[strlen((char *)inet_ntoa(addr))]='\0';
}
} else {
// we're using an address from -A
if (!option_M) {
// if no mask was specified, then use just a host mask
if ( ( dst_mask = (char *)malloc(16) ) == NULL ) malloc_fail("dest_mask", 16);
strncpy(dst_mask,"255.255.255.255",15);
}
}
f_size = strlen("port 53 and dst net mask ")+ strlen(dst_mask)+ strlen(dst_addr);
if ( ( filter = (char *) malloc ( f_size+1) ) == NULL ) malloc_fail( "filter", f_size+1 );
snprintf( filter, f_size, "port 53 and dst net %s mask %s", dst_addr, dst_mask);
free (dst_mask);
free (dst_addr);
}
if ( option_b && option_v ) {
printf("using filter \"%s\" on dev %s\n", filter, dev);
}
// open device for reading only local traffic
descr = pcap_open_live(dev,1500,0,1,errbuf);
if(descr == NULL) {
@ -671,11 +797,13 @@ int main(int argc,char **argv){
// compile filter
if(pcap_compile(descr,&fp,filter,0,netp) == -1) {
fprintf(stderr,"error compiling filter: %s\n",pcap_geterr(descr));
exit(1);
}
// set filter
if(pcap_setfilter(descr,&fp) == -1){
fprintf(stderr,"error setting filter: %s\n",pcap_geterr(descr));
exit(1);
}

11
dns_flood_detector.h
View file

@ -29,7 +29,7 @@
#define ETHER_HDRLEN 14
#endif
#define NS_MAXDNAME 1025
#define MAXSYSLOG 128
#define MAXSYSLOG 192
// evil Solaris hack
#ifdef __sun__
@ -40,7 +40,12 @@ typedef uint32_t u_int32_t;
// prototypes
void handle_IP(u_char *args,const struct pcap_pkthdr* pkthdr,const u_char* packet);
int calculate_averages();
int scour_bucket(int i);
int find_bucket(struct in_addr *ip_src);
int daemonize(void);
int malloc_fail(char * var, int size);
// data structures
struct my_dns {
u_int16_t dns_id; /* query identification number */
@ -53,7 +58,7 @@ struct my_dns {
};
struct bucket {
char * ip_addr;
struct in_addr ip_addr;
unsigned int tcp_count;
unsigned int udp_count;
unsigned int qps;

2
makefiles/Makefile-BSDI
View file

@ -7,5 +7,7 @@ clean:
rm -rf dns_flood_detector *.o *~
install:
cp dns_flood_detector /usr/local/sbin/
distclean: clean
rm Makefile
dns_flood_detector: dns_flood_detector.c

2
makefiles/Makefile-FreeBSD
View file

@ -7,5 +7,7 @@ clean:
rm -rf dns_flood_detector *.o *~
install:
cp dns_flood_detector /usr/local/sbin/
distclean: clean
rm Makefile
dns_flood_detector: dns_flood_detector.c

4
makefiles/Makefile-Linux
View file

@ -1,4 +1,4 @@
CFLAGS=-O -D_BSD_SOURCE -g
CFLAGS=-Wall -O -D_BSD_SOURCE -g
LDLIBS=-lpcap -lpthread -lm
all: dns_flood_detector
@ -7,5 +7,7 @@ clean:
rm -rf dns_flood_detector *.o *~
install:
cp dns_flood_detector /usr/local/sbin/
distclean: clean
rm Makefile
dns_flood_detector: dns_flood_detector.c

4
makefiles/Makefile-OSX
View file

@ -1,4 +1,4 @@
CFLAGS+=-O -g -I/usr/local/include -I/usr/include
CFLAGS+=-Wall -O -g -I/usr/local/include -I/usr/include
LDLIBS=-L/usr/local/lib -lpcap -lpthread -lm
all: dns_flood_detector
@ -7,5 +7,7 @@ clean:
rm -rf dns_flood_detector *.o *~
install:
cp dns_flood_detector /usr/local/sbin/
distclean: clean
rm Makefile
dns_flood_detector: dns_flood_detector.c

2
makefiles/Makefile-Solaris
View file

@ -7,5 +7,7 @@ clean:
rm -rf dns_flood_detector *.o *~
install:
cp dns_flood_detector /usr/local/sbin/
distclean: clean
rm Makefile
dns_flood_detector: dns_flood_detector.c