February 13th, 2008, 05:16 PM
WinPCap packet sending
Hi I have a problem with winpcap while sending ICMP (ping) packet..
heres the code...
#pragma pack(push, 1)
unsigned char ip_ver_ihl;
unsigned char ip_tos;
unsigned short ip_len;
unsigned short ip_id;
unsigned short ip_off;
unsigned char ip_ttl;
unsigned char ip_p;
unsigned short ip_sum;
unsigned int saddr;
unsigned int daddr;
unsigned char type;
unsigned char code;
unsigned short checksum;
unsigned short id;
unsigned short seqno;
// WinPCap handle (adhandle) was successfully opened previously...
int nSize = sizeof(IP_HEADER) + sizeof(ICMP_HEADER);
char* Data = (char *) malloc (nSize);
IP_HEADER* ip = (IP_HEADER*)Data;
ICMP_HEADER* icmp = (ICMP_HEADER*)(Data+sizeof(IP_HEADER));
ip->ip_sum = 0;
ip->ip_ver_ihl = 0x45;
ip->ip_tos = 0;
ip->ip_len = nSize;
ip->ip_id = GetCurrentProcessId();
ip->ip_off = 0;
ip->ip_ttl = 128;
ip->ip_p = IPPROTO_ICMP;
ip->saddr = inet_addr(src_addr);
ip->daddr = inet_addr(dest_addr);
ip->ip_sum = in_cksum((unsigned short*)ip,sizeof(IP_HEADER));
icmp->type = 8;
icmp->checksum = 0;
icmp->code = 0;
icmp->id = GetCurrentProcessId();
icmp->seqno = 0;
icmp->checksum = in_cksum((unsigned short*)icmp,sizeof(ICMP_HEADER));
if( pcap_sendpacket(adhandle,(u_short*)Data,nSize) != 0)
unsigned short in_cksum(unsigned short *data, int size)
register int nleft=size;
unsigned long checksum = 0;
return (unsigned short)(~checksum);
pcap_sendpacket() works ok since it doesn't return nonzero value...
but when using packet sniffers (Winshark) I just can't see the packet itself...
I also tried to re-create the IP header with the one located on http://www.wikistc.org/wiki/Network_packet_generator (under the Sample packets and TCP/IP ICMP Echo Request )
it went ok but checksum was bad - it states it should be "b8 c8" but mine is "a8 d8"
is the checksum algorithm ok?
I have SP2 so I know I can't send custom crafted packets using winsock.
But can I do it with third party programs/drivers like WinPCap?
help me out here will ya'...
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