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<hr><p align="left"><small>:发信人: scz (小四), 信区: Security <br>
:标 题: linuxtcp.c(修改) <br>
:发信站: 武汉白云黄鹤站 (Thu Oct 26 11:18:07 2000), 站内信件 <br>
/* <br>
* File : linuxtcp.c <br>
* Version: <br>
* Author : Anonymous ( Don't ask anything about this program, please. ) <br>
* Complie: gcc -O3 -o lt linuxtcp.c <br>
* : strip lt <br>
* Usage : ./lt -h <br>
* Date : 2000-10-25 20:55 <br>
* <br>
*/ <br>
/******************************************************************* <br>
* * <br>
* Head File * <br>
* * <br>
*******************************************************************/ <br>
#include <stdio.h> <br>
#include <stdlib.h> <br>
#include <strings.h> <br>
#include <sys/signal.h> <br>
#include <sys/socket.h> <br>
#include <sys/types.h> <br>
#include <netinet/in.h> <br>
#include <netinet/in_systm.h> <br>
#include <netdb.h> <br>
#include <netinet/ip.h> <br>
#include <netinet/tcp.h> <br>
#include <errno.h> <br>
#include <unistd.h> <br>
/******************************************************************* <br>
* * <br>
* Macro * <br>
* * <br>
*******************************************************************/ <br>
#define SUCCESS 0 <br>
#define FAILURE -1 <br>
#define HIGHPORT 65535 <br>
#define LOWPORT 1 <br>
#define SYNSIZE ( sizeof( struct iphdr ) + sizeof( struct tcphdr ) ) <br>
typedef void Sigfunc ( int ); /* for signal handlers */ <br>
/******************************************************************* <br>
* * <br>
* Static Global Var * <br>
* * <br>
*******************************************************************/ <br>
struct sockaddr_in server; <br>
struct in_addr serverIp = { 0 }; <br>
struct in_addr clientIp = { 0 }; <br>
u_short clientPort = 1977; <br>
int sendSocket = -1; <br>
int recvSocket = -1; <br>
u_short ports[ HIGHPORT + 1 ]; <br>
int portIndex; <br>
u_short lowPort = LOWPORT; <br>
u_short highPort = HIGHPORT; <br>
/******************************************************************* <br>
* * <br>
* Function Prototype * <br>
* * <br>
*******************************************************************/ <br>
void Atexit ( void ( * func ) ( void ) ); <br>
void Close ( int fd ); <br>
u_short in_cksum ( u_short * addr, int len ); <br>
u_long resolveHost ( char * host ); <br>
int sendSyn ( u_long sourceIp, u_short sourcePort, u_long seqNum, <br>
u_lo <br>
ng ackNum, struct sockaddr_in * dest ); <br>
void sig_end ( int signo ); <br>
Sigfunc * signal ( int signo, Sigfunc * func ); <br>
Sigfunc * Signal ( int signo, Sigfunc * func ); /* for our signal() fu <br>
ncti <br>
on */ <br>
int Socket ( int family, int type, int protocol ); <br>
int synScan ( u_long sourceIp, u_short sourcePort, u_short lowPort <br>
, u_ <br>
short highPort, struct sockaddr_in * dest ); <br>
void terminate ( void ); <br>
void usage ( char * arg ); <br>
/*----------------------------------------------------------------------*/ <br>
void Atexit ( void ( * func ) ( void ) ) <br>
{ <br>
if ( atexit( func ) != 0 ) <br>
{ <br>
perror( "atexit" ); <br>
exit( FAILURE ); <br>
} <br>
return; <br>
return; <br>
} /* end of Atexit */ <br>
void Close ( int fd ) <br>
{ <br>
if ( close( fd ) == -1 ) <br>
{ <br>
perror( "close" ); <br>
exit( FAILURE ); <br>
} <br>
return; <br>
} /* end of Close */ <br>
u_short in_cksum ( u_short * addr, int len ) <br>
{ <br>
int nleft = len; <br>
int sum = 0; <br>
u_short * w = addr; <br>
u_short answer = 0; <br>
/* <br>
* Our algorithm is simple, using a 32 bit accumulator (sum), we add <br>
* sequential 16 bit words to it, and at the end, fold back all the <br>
* carry bits from the top 16 bits into the lower 16 bits. <br>
*/ <br>
while ( nleft > 1 ) <br>
{ <br>
sum += *w++; <br>
nleft -= 2; <br>
} <br>
/* 4mop up an odd byte, if necessary */ <br>
if ( nleft == 1 ) <br>
{ <br>
*( unsigned char * )(&answer) = *( unsigned char * )w ; <br>
sum += answer; <br>
} <br>
/* 4add back carry outs from top 16 bits to low 16 bits */ <br>
sum = ( sum >> 16 ) + ( sum & 0xffff ); /* add hi 16 to low 16 */ <br>
sum += ( sum >> 16 ); /* add carry */ <br>
answer = ~sum; /* truncate to 16 bits */ <br>
return( answer ); <br>
} /* end in_cksum */ <br>
u_long resolveHost ( char * host ) <br>
{ <br>
struct hostent * he; <br>
unsigned long ip; <br>
if( ( he = gethostbyname( host ) ) == NULL ) <br>
{ <br>
{ <br>
ip = inet_addr( host ); <br>
if ( ip == INADDR_NONE ) <br>
{ <br>
fprintf( stderr, "Unknown host %s\n", host ); <br>
exit( FAILURE ); <br>
} <br>
} <br>
else <br>
{ <br>
memcpy( &ip, he->h_addr_list[0], sizeof( unsigned long ) ); <br>
} <br>
return( ip ); /* network */ <br>
} /* end of resolveHost */ <br>
int sendSyn ( u_long sourceIp, u_short sourcePort, u_long seqNum, u_long ack <br>
Num, <br>
struct sockaddr_in * dest ) <br>
{ <br>
u_char packet[ SYNSIZE ]; <br>
struct iphdr * ip; <br>
struct tcphdr * tcp; <br>
u_char * pPseudoHead; <br>
u_char pseudoHead[ 12 + sizeof( struct tcphdr ) ]; <br>
u_short tcpHeadLen; /* network */ <br>
memset( packet, 0, SYNSIZE ); <br>
ip = ( struct iphdr * )packet; <br>
ip->ihl = 5; <br>
ip->version = 4; <br>
ip->tos = 0; <br>
ip->tot_len = htons( SYNSIZE ); <br>
ip->id = htons( 1977 + ( rand() % 32768 ) ); <br>
ip->frag_off = 0; <br>
ip->ttl = 255; <br>
ip->protocol = IPPROTO_TCP; <br>
ip->check = 0; <br>
ip->saddr = sourceIp; <br>
ip->daddr = dest->sin_addr.s_addr; <br>
tcpHeadLen = htons( sizeof(struct tcphdr) ); /* network */ <br>
tcp = (struct tcphdr *)( packet + sizeof( struct iphdr ) ); <br>
tcp->source = htons( sourcePort ); <br>
tcp->dest = dest->sin_port; <br>
tcp->seq = htonl( seqNum ); <br>
tcp->ack_seq = htonl( ackNum ); <br>
tcp->doff = 5; <br>
tcp->syn = 1; <br>
tcp->window = htons( 8192 ); <br>
tcp->check = 0; <br>
tcp->urg_ptr = 0; <br>
pPseudoHead = pseudoHead; <br>
memset( pPseudoHead, 0, sizeof( pseudoHead ) ); <br>
memmove( pPseudoHead, &( ip->saddr ), 8 ); <br>
pPseudoHead += 9; <br>
memmove( pPseudoHead, &( ip->protocol ), 1 ); <br>
pPseudoHead++; <br>
memmove( pPseudoHead, &tcpHeadLen, 2 ); <br>
pPseudoHead += 2; <br>
memmove( pPseudoHead, tcp, sizeof( struct tcphdr ) ); <br>
tcp->check = in_cksum( ( u_short * )pseudoHead, sizeof( pseudoHead ) ) <br>
; <br>
return( sendto( sendSocket, packet, SYNSIZE, 0, ( struct sockaddr * )des <br>
t, s <br>
izeof( struct sockaddr_in ) ) ); <br>
} /* end of sendSyn */ <br>
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