用winpacp監聽並分析 FTP 協議並記錄 IP、使用者名稱、密碼和登陸是否成功
阿新 • • 發佈：2018-11-24
為了完成計算機網路的實驗，翻了一些部落格，有的沒原始碼，有的記錄不全。就很煩。所以自己寫一篇吧。
首先我們通過wireshark看看FTP的登陸是怎麼完成的。
（1）選一個當前在用的網路，我是WLAN
（2）選擇TCP過濾器方便找到FTP的包（沒有過濾FTP的，最多隻能過濾出TCP）
（3）開始捕捉後我們就可以找到需要的包了。右鍵一個FTP包，點跟蹤流，可以看到所有相關的包。
OK，現在我們已經知道FTP登陸的過程了。一個頭部是USER的包，一個頭部是PASS的包，以及頭部是530表示登入失敗（230代表成功）的包。三個包就足夠讓我們開一個暴力的beta程式了。
開始程式設計吧。我們首先要設定在程式中設定TCP過濾器。如下：
char packet_filter[] = "tcp"; //編譯過濾器 if (pcap_compile(adhandle, &fcode, packet_filter, 1, netmask) <0) { fprintf(stderr, "\nUnable to compile the packet filter. Check the syntax.\n"); /* 釋放裝置列表 */ pcap_freealldevs(alldevs); return -1; } //設定過濾器 if (pcap_setfilter(adhandle, &fcode)<0) { fprintf(stderr, "\nError setting the filter.\n"); /* 釋放裝置列表 */ pcap_freealldevs(alldevs); return -1; }
然後在回撥函式中，我們讀取每個包資訊部分（注意要跳過頭部）的前四個字元，進行判斷如下：
string com;//讀取 for (int i = 0; i < 4; i++) com += (char)pkt_data[head + i]; if (com == "USER") { string m_ip_message = get_request_m_ip_message(pkt_data); string user; ostringstream sout; for (int i = head+5; pkt_data[i]!=13; i++) { sout << pkt_data[i]; } user = sout.str(); ftp[m_ip_message][0] = user; } if (com == "PASS") { string m_ip_message = get_request_m_ip_message(pkt_data); string pass; ostringstream sout; for (int i = head + 5; pkt_data[i] != 13; i++) { sout << pkt_data[i]; } pass = sout.str(); ftp[m_ip_message][1] = pass; } if (com == "230 ") { string m_ip_message = get_response_m_ip_message(pkt_data); ftp[m_ip_message][2] = "SUCCEED"; print(header, m_ip_message); } if (com == "530 ") { string m_ip_message = get_response_m_ip_message(pkt_data); ftp[m_ip_message][2] = "FAILD"; print(header, m_ip_message); }
FTP是一個map<string,string[3]> 記錄了以某兩臺電腦之間通訊的USER PASS以及訪問狀態。這樣可以避免多個FTP同時訪問造成錯誤。完成程式碼如下：
#include<iostream>
#include<sstream>
#include<string>
#include<map>
#include<fstream>
#include <pcap.h>
#pragma warning(disable:4996)
using namespace std;
map<string,string[3]> ftp;
bool flag;
ofstream out("mark.txt");
typedef struct mac_header
{
u_char dest_addr[6];
u_char src_addr[6];
u_char type[2];
} mac_header;
/* IPv4 首部 ,20位元組*/
typedef struct ip_header {
u_char ver_ihl; // 版本 (4 bits) + 首部長度 (4 bits)
u_char tos; // 服務型別(Type of service)
u_short tlen; // 總長(Total length)
u_short identification; // 標識(Identification)
u_short flags_fo; // 標誌位(Flags) (3 bits) + 段偏移量(Fragment offset) (13 bits)
u_char ttl; // 存活時間(Time to live)
u_char proto; // 協議(Protocol)
u_short crc; // 首部校驗和(Header checksum)
u_char saddr[4]; // 源地址(Source address)
u_char daddr[4]; // 目的地址(Destination address)
u_int op_pad; // 選項與填充(Option + Padding)
}ip_header;
//TCP頭部，總長度20位元組
typedef struct tcp_header
{
u_short sport; //源埠號
u_short dport; //目的埠號
u_int th_seq; //序列號
u_int th_ack; //確認號
u_int th1 : 4; //tcp頭部長度
u_int th_res : 4; //6位中的4位首部長度
u_int th_res2 : 2; //6位中的2位首部長度
u_char th_flags; //6位標誌位
u_short th_win; //16位視窗大小
u_short th_sum; //16位tcp檢驗和
u_short th_urp; //16位緊急指標
}tcp_header;
/* 回撥函式原型 */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data);
string get_request_m_ip_message(const u_char* pkt_data);
string get_response_m_ip_message(const u_char* pkt_data);
void print(const struct pcap_pkthdr *header, string m_ip_message);
int main()
{
flag = false;
pcap_if_t *alldevs;
pcap_if_t *d;
int inum;
int i = 0;
pcap_t *adhandle;
char errbuf[PCAP_ERRBUF_SIZE];
u_int netmask;
char packet_filter[] = "tcp";
struct bpf_program fcode;
/* 獲得裝置列表 */
if (pcap_findalldevs_ex(PCAP_SRC_IF_STRING, NULL, &alldevs, errbuf) == -1)
{
fprintf(stderr, "Error in pcap_findalldevs: %s\n", errbuf);
exit(1);
}
/* 列印列表 */
for (d = alldevs; d; d = d->next)
{
printf("%d. %s", ++i, d->name);
if (d->description)
printf(" (%s)\n", d->description);
else
printf(" (No description available)\n");
}
if (i == 0)
{
printf("\nNo interfaces found! Make sure WinPcap is installed.\n");
return -1;
}
printf("Enter the interface number (1-%d):", i);
scanf("%d", &inum);
if (inum < 1 || inum > i)
{
printf("\nInterface number out of range.\n");
/* 釋放裝置列表 */
pcap_freealldevs(alldevs);
return -1;
}
/* 跳轉到已選裝置 */
for (d = alldevs, i = 0; i< inum - 1; d = d->next, i++);
/* 開啟介面卡 */
if ((adhandle = pcap_open(d->name, // 裝置名
65536, // 要捕捉的資料包的部分
// 65535保證能捕獲到不同資料鏈路層上的每個資料包的全部內容
PCAP_OPENFLAG_PROMISCUOUS, // 混雜模式
1000, // 讀取超時時間
NULL, // 遠端機器驗證
errbuf // 錯誤緩衝池
)) == NULL)
{
fprintf(stderr, "\nUnable to open the adapter. %s is not supported by WinPcap\n", d->name);
/* 釋放裝置列表 */
pcap_freealldevs(alldevs);
return -1;
}
/* 檢查資料鏈路層，為了簡單，我們只考慮乙太網 */
if (pcap_datalink(adhandle) != DLT_EN10MB)
{
fprintf(stderr, "\nThis program works only on Ethernet networks.\n");
/* 釋放裝置列表 */
pcap_freealldevs(alldevs);
return -1;
}
if (d->addresses != NULL)
/* 獲得介面第一個地址的掩碼 */
netmask = ((struct sockaddr_in *)(d->addresses->netmask))->sin_addr.S_un.S_addr;
else
/* 如果介面沒有地址，那麼我們假設一個C類的掩碼 */
netmask = 0xffffff;
//編譯過濾器
if (pcap_compile(adhandle, &fcode, packet_filter, 1, netmask) <0)
{
fprintf(stderr, "\nUnable to compile the packet filter. Check the syntax.\n");
/* 釋放裝置列表 */
pcap_freealldevs(alldevs);
return -1;
}
//設定過濾器
if (pcap_setfilter(adhandle, &fcode)<0)
{
fprintf(stderr, "\nError setting the filter.\n");
/* 釋放裝置列表 */
pcap_freealldevs(alldevs);
return -1;
}
printf("\nlistening on %s...\n", d->description);
/* 釋放裝置列表 */
pcap_freealldevs(alldevs);
/* 開始捕捉 */
pcap_loop(adhandle, 0, packet_handler, NULL);
out.close();
return 0;
}
/* 回撥函式，當收到每一個數據包時會被libpcap所呼叫 */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)
{
struct tm *ltime;
char timestr[16];
ip_header *ih;
tcp_header *uh;
u_int ip_len;
u_short sport, dport;
time_t local_tv_sec;
/* 將時間戳轉換成可識別的格式 */
local_tv_sec = header->ts.tv_sec;
ltime = localtime(&local_tv_sec);
strftime(timestr, sizeof timestr, "%H:%M:%S", ltime);
int head = 54;//14位乙太網頭，20位ip頭，20位tcp頭
//選擇出command為USER和PASS的包，當然這裡就簡單的以首字母來代表了，反正其他的
//command 沒有以U和P開頭的
string com;
for (int i = 0; i < 4; i++)
com += (char)pkt_data[head + i];
if (com == "USER")
{
string m_ip_message = get_request_m_ip_message(pkt_data);
string user;
ostringstream sout;
for (int i = head+5; pkt_data[i]!=13; i++)
{
sout << pkt_data[i];
}
user = sout.str();
ftp[m_ip_message][0] = user;
}
if (com == "PASS")
{
string m_ip_message = get_request_m_ip_message(pkt_data);
string pass;
ostringstream sout;
for (int i = head + 5; pkt_data[i] != 13; i++)
{
sout << pkt_data[i];
}
pass = sout.str();
ftp[m_ip_message][1] = pass;
}
if (com == "230 ")
{
string m_ip_message = get_response_m_ip_message(pkt_data);
ftp[m_ip_message][2] = "SUCCEED";
print(header, m_ip_message);
}
if (com == "530 ")
{
string m_ip_message = get_response_m_ip_message(pkt_data);
ftp[m_ip_message][2] = "FAILD";
print(header, m_ip_message);
}
/*if (flag == true)
{
cout << com;
for (int i = 0; i < 4; i++)
{
int a = com.c_str()[i];
cout << " " << a;
}
cout << endl;
}*/
}
string get_request_m_ip_message(const u_char* pkt_data)
{
mac_header *mh;
ip_header *ih;
string m_ip_message;
string str;//empty string
ostringstream sout;
int length = sizeof(mac_header) + sizeof(ip_header);
mh = (mac_header*)pkt_data;
ih = (ip_header*)(pkt_data + sizeof(mac_header));
for (int i = 0; i<5; i++)
sout << hex << (int)(mh->src_addr[i]) << "-";
sout << (int)(mh->src_addr[5]) << ",";
for (int i = 0; i<3; i++)
sout << dec << (int)(ih->saddr[i]) << ".";
sout << (int)(ih->saddr[3]) << ",";
for (int i = 0; i<5; i++)
sout << hex << (int)(mh->dest_addr[i]) << "-";
sout << (int)(mh->dest_addr[5]) << ",";
for (int i = 0; i < 3; i++)
sout << dec << (int)(ih->daddr[i]) << ".";
sout << (int)(ih->daddr[3]);
m_ip_message = sout.str();
return m_ip_message;
}
string get_response_m_ip_message(const u_char* pkt_data)
{
mac_header *mh;
ip_header *ih;
string m_ip_message;
string str;//empty string
ostringstream sout;
int length = sizeof(mac_header) + sizeof(ip_header);
mh = (mac_header*)pkt_data;
ih = (ip_header*)(pkt_data + sizeof(mac_header));
for (int i = 0; i<5; i++)
sout << hex << (int)(mh->dest_addr[i]) << "-";
sout << (int)(mh->dest_addr[5]) << ",";
for (int i = 0; i < 3; i++)
sout << dec << (int)(ih->daddr[i]) << ".";
sout << (int)(ih->daddr[3]) << ",";
for (int i = 0; i<5; i++)
sout << hex << (int)(mh->src_addr[i]) << "-";
sout << (int)(mh->src_addr[5]) << ",";
for (int i = 0; i<3; i++)
sout << dec << (int)(ih->saddr[i]) << ".";
sout << (int)(ih->saddr[3]);
m_ip_message = sout.str();
return m_ip_message;
}
void print(const struct pcap_pkthdr *header, string m_ip_message)
{
struct tm *ltime;
char timestr[16];
time_t local_tv_sec;
/* 將時間戳轉化為可識別的格式 */
local_tv_sec = header->ts.tv_sec;
ltime = localtime(&local_tv_sec);
strftime(timestr, sizeof timestr, "%H:%M:%S", ltime);
/* 列印時間戳*/
cout << timestr << ",";
cout << m_ip_message << ",";
for (int i = 0; i < 2; i++)
cout << ftp[m_ip_message][i] << ",";
cout << ftp[m_ip_message][2] <<endl;
out << timestr << ",";
out << m_ip_message << ",";
for (int i = 0; i < 2; i++)
out << ftp[m_ip_message][i] << ",";
out << ftp[m_ip_message][2] << endl;
ftp.erase(m_ip_message);
}