計算機(jī)網(wǎng)絡(luò)課程設(shè)計實驗報告

計算機(jī)網(wǎng)絡(luò)課程設(shè)計實驗報告一、 實驗內(nèi)容和要求1、實驗一 數(shù)據(jù)包的捕獲與分析Wireshark是一種開源的網(wǎng)絡(luò)數(shù)據(jù)包的捕獲和分析軟件，本實驗通過Wireshark軟件的安裝使用，監(jiān)控局域網(wǎng)的狀態(tài)，捕獲在局域網(wǎng)中傳輸?shù)臄?shù)據(jù)包，并結(jié)合在計算機(jī)網(wǎng)絡(luò)課程中學(xué)習(xí)到的理論知識，對常用網(wǎng)絡(luò)協(xié)議的數(shù)據(jù)包做出分析，加深網(wǎng)絡(luò)課程知識的理解和掌握。具體內(nèi)容及要求如下：l Wireshark軟件的安裝；l Wireshark軟件的啟動，并設(shè)置網(wǎng)卡的狀態(tài)為混雜狀態(tài)，使得Wireshark可以監(jiān)控局域網(wǎng)的狀態(tài)；l 啟動數(shù)據(jù)包的捕獲，跟蹤PC之間的報文，并存入文件以備重新查；l 設(shè)置過濾器過濾網(wǎng)絡(luò)報文以檢測特定數(shù)據(jù)流；l 對常用協(xié)議的數(shù)據(jù)包的報文格式進(jìn)行分析，利用協(xié)議分析軟件的統(tǒng)計工具顯示網(wǎng)絡(luò)報文的各種統(tǒng)計信息。2、實驗二 網(wǎng)絡(luò)層實驗Ping程序的設(shè)計與實現(xiàn)實驗?zāi)康?本實驗?zāi)康氖鞘箤W(xué)生掌握網(wǎng)絡(luò)層協(xié)議的原理及實現(xiàn)方法。 實驗設(shè)計內(nèi)容本實驗為ICMP實驗。實驗內(nèi)容：Ping命令實現(xiàn)的擴(kuò)充，在給定的Ping程序的基礎(chǔ)上做如下功能擴(kuò)充：-h顯示幫助信息-b允許ping一個廣播地址，只用于IPv4-t 設(shè)置ttl值，只用于IPv4-q安靜模式。不顯示每個收到的包的分析結(jié)果，只在結(jié)束時，顯示匯總結(jié)果Ping命令的基本描述Ping的操作是向某些IP地址發(fā)送一個ICMP Echo消息，接著該節(jié)點返回一個ICMP Echo replay消息。ICMP消息使用IP頭作為基本控制。二、實驗環(huán)境實驗一 數(shù)據(jù)包的捕獲與分析1.聯(lián)網(wǎng)計算機(jī)2.Windows 或linux 系統(tǒng)3.在P中安裝協(xié)議分析軟件（如：Wireshark）4.物理基礎(chǔ)：IEEE802.3 標(biāo)準(zhǔn)的以太網(wǎng)采用的是持續(xù) CSMA 的方式，正是由于以太網(wǎng)采用這種廣播信道爭用的方式，使得各個站點可以獲得其他站點發(fā)送的數(shù)據(jù)。運用這一原理使信息捕獲系統(tǒng)能夠攔截的我們所要的信5.工作模式：1) 廣播模式（Broad Cast Model）：它的物理地址（MAC）地址是 0Xffffff 的幀為廣播幀，工作在廣播模式的網(wǎng)卡接收廣播幀。2） 多播傳送（MultiCast Model）：多播傳送地址作為目的物理地址的幀可以被組內(nèi)的其它主機(jī)同時接收，而組外主機(jī)卻接收不到。但是，如果將網(wǎng)卡設(shè)置為 多播傳送模式，它可以接收所有的多播傳送幀，而不論它是不是組內(nèi)成員。3） 直接模式（Direct Model）：工作在直接模式下的網(wǎng)卡只接收目地址是自己 MAC地址的幀。4） 混雜模式（Promiscuous Model）：工作在混雜模式下的網(wǎng)卡接收所有的流過網(wǎng)卡的幀，信包捕獲程序就是在這種模式下運行的。實驗二 網(wǎng)絡(luò)層實驗Ping程序的設(shè)計與實現(xiàn)1. 聯(lián)網(wǎng)計算機(jī)2. Linux系統(tǒng)3. 系統(tǒng)自帶編譯環(huán)境三、 程序的需求分析與邏輯框圖需求分析1、實驗一數(shù)據(jù)包的捕獲與分析1.在P中安裝協(xié)議分析軟件。2.啟動Wireshark協(xié)議分析軟件，選擇抓包菜單項啟動實時監(jiān)視器，開始實時跟蹤顯示網(wǎng)絡(luò)數(shù)據(jù)報文?？筛鶕?jù)系統(tǒng)提示修改顯示方式。3.調(diào)出跟蹤存儲的歷史報文，選擇有代表性的ETHERNET，IEEE802.3，IP，ICMP，TCP，UDP報文，對照有關(guān)協(xié)議逐個分析報文各字段的含義及內(nèi)容。4.設(shè)置過濾器屬性，如目的地址，源地址，協(xié)議類型等。如過濾不需要的網(wǎng)絡(luò)報文，過濾器允許設(shè)置第二層，第三層或第四層的協(xié)議字段。2、實驗二網(wǎng)絡(luò)層實驗Ping程序的設(shè)計與實現(xiàn)PING程序是我們使用的比較多的用于測試網(wǎng)絡(luò)連通性的程序。PING程序給予ICMP使用ICMP的回送請求和回送應(yīng)答來工作。ICMP是基于IP的一個協(xié)議，ICMP包通過IP的封裝之后傳遞。實現(xiàn)檢測網(wǎng)絡(luò)通暢及速度的ping，并擴(kuò)展以下功能：-h 顯示幫助信息-b 允許ping一個廣播地址，只用于IPv4-t 設(shè)置ttl值，只用于IPv4-q 安靜模式，不顯示每個收到的包的分析結(jié)果，只在結(jié)束時，顯示匯總結(jié)果三、程序的需求分析與邏輯框圖邏輯框圖1、 總體設(shè)計程序分為兩大部分：一部分讀取收到的所有消息，并輸出ICMP Echo replay消息，另一部分每個一秒鐘發(fā)送一個Echo消息。另一部分由SIGALARM信號每秒驅(qū)動一次。2、 詳細(xì)設(shè)計1）main函數(shù)三、程序的需求分析與邏輯框圖邏輯框圖2）readloop函數(shù) 3）proc函數(shù) 4）send函數(shù) 三、程序的需求分析與邏輯框圖邏輯框圖Checksum開始定義初始化cksum (size 1)確定cksum及size大小是if (size)計算校驗cksum，獲得結(jié)果cksum += *(UCHAR*)buffer;否結(jié)束四、程序核心功能的實現(xiàn)機(jī)制1、實驗一 利用協(xié)議分析軟件跟蹤局域網(wǎng)報文，實驗內(nèi)容如下：將安裝協(xié)議分析軟件的PC接入以太網(wǎng)中，跟蹤PC之間的報文，并存入文件以備重新查。設(shè)置過濾器過濾網(wǎng)絡(luò)報文以檢測特定數(shù)據(jù)流。利用協(xié)議分析軟件的統(tǒng)計工具顯示網(wǎng)絡(luò)報文的各種統(tǒng)計信息。2、實驗二Ping命令的基本描述Ping的操作是向某些IP地址發(fā)送一個ICMP Echo消息，接著該節(jié)點返回一個ICMP Echo replay消息。ICMP消息使用IP頭作為基本控制。IP頭的格式如下0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version| IHL |Type of Service| Total Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identification |Flags| Fragment Offset| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time to Live | Protocol | Header Checksum| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Version=4 IHL Internet頭長 Type of Service = 0 Total Length IP包的總長度 Identification, Flags, Fragment Offset 用于IP包分段 Time to Live IP包的存活時長 Protocol ICMP = 1 Addresses 發(fā)送Echo消息的源地址是發(fā)送Echo reply消息的目的地址,相反,發(fā)送Echo 消息的目的地址是發(fā)送Echo reply消息的源地址。四、 程序核心功能的實現(xiàn)機(jī)制2、實驗二Ping實際上是使用ICMP中的ECHO報文來實現(xiàn)的。Echo 或 Echo Reply 消息格式如下: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Data . +-+-+-+-+-Typeecho消息的類型為8 echo reply 的消息類型為0。Code=0Checksum為從TYPE開始到IP包結(jié)束的校驗和Identifier 如果 code = 0, identifier用來匹配echo和echo reply消息Sequence Number 如果 code = 0, identifier用來匹配echo和echo reply消息功能描述: 收到echo 消息必須回應(yīng) echo reply 消息。 identifier 和 sequence number 可能被發(fā)送echo的主機(jī)用來匹配返回的 echo reply消息。例如: identifier 可能用于類似于TCP或UDP的 port 用來標(biāo)示一個會話, 而sequence number 會在每次發(fā)送echo請求后遞增。收到echo的主機(jī)或路由器返回同一個值與之匹配四、程序核心功能的實現(xiàn)機(jī)制2、實驗二1、數(shù)據(jù)結(jié)構(gòu)的描述1) IP包格式struct ip BYTE Ver_ihl; /版本號與包頭長度BYTE TOS; /服務(wù)類型WORD Leng; /IP包長度WORD Id; /IP包標(biāo)示,用于輔助IP包的拆裝,本實驗不用,置零WORD Flg_offset; /偏移量,也是用于IP包的拆裝,本實驗不用,置零BYTE TTL; /IP包的存活時間BYTE Protocol; /上一層協(xié)議,本實驗置ICMPWORD Checksum; /包頭校驗和,最初置零,等所有包頭都填寫正確后,計算并替換。BYTE Saddr4; /源端IP地址BYTE Daddr4; /目的端IP地址BYTE Data1; /IP包數(shù)據(jù);2）ICMP包格式struct icmp BYTE Type; /ICMP類型,本實驗用 8: ECHO 0:ECHO REPLYBYTE Code; /本實驗置零WORD Checksum; /ICMP包校驗和,從TYPE開始,直到最后一位用戶數(shù)據(jù),如果為字節(jié)數(shù)為奇數(shù)則補(bǔ)充一位WORD ID; /用于匹配ECHO和ECHO REPLY包WORD Seq; /用于標(biāo)記ECHO報文順序BYTE Data1; /用戶數(shù)據(jù);五、程序源代碼（核心部分）2、實驗二PING.H#ifndef PING_H_#define PING_H_#include #include#include#include#include#include/* basic system data types */#include/* basic socket definitions */#include/* timeval for select() */#include/* timespec for pselect() */#include/* sockaddr_in and other Internet defns */#include/* inet(3) functions */#include#include#include#include#include#include#include #include#include/* for Unix domain sockets */#include#include#include #include #ifdef HAVE_SOCKADDR_DL_STRUCT# include #endif#define BUFSIZE1500#define MAXLINE 4096/* globals */char recvbufBUFSIZE;char sendbufBUFSIZE;int ttl_signal;int ttl_value;char *ttl_val;int datalen;/* #bytes of data, following ICMP header */char*host;int broad_sign=0;int nsent;/* add 1 for each sendto() */pid_t pid;/* our PID */int sockfd;int verbose;int daemon_proc; /* set nonzero by daemon_init() */* function prototypes */void proc_v4(char *, ssize_t, struct timeval *);void proc_v6(char *, ssize_t, struct timeval *);void send_v4(void);void send_v6(void);void readloop(void);void sig_alrm(int);void tv_sub(struct timeval *, struct timeval *);char * Sock_ntop_host(const struct sockaddr *sa, socklen_t salen);struct addrinfo* host_serv(const char *host, const char *serv, int family, int socktype);static void err_doit(int errnoflag, int level, const char *fmt, va_list ap);void err_quit(const char *fmt, .);void err_sys(const char *fmt, .);struct proto void (*fproc)(char *, ssize_t, struct timeval *); void (*fsend)(void); struct sockaddr *sasend;/* sockaddr for send, from getaddrinfo */ struct sockaddr *sarecv;/* sockaddr for receiving */ socklen_t salen;/* length of sockaddrs */ int icmpproto;/* IPPROTO_xxx value for ICMP */ *pr;#endif /* PING_H_ */PING.C#include ping.h struct protoproto_v4 = proc_v4, send_v4, NULL, NULL, 0, IPPROTO_ICMP ;#ifdefIPV6struct protoproto_v6 = proc_v6, send_v6, NULL, NULL, 0, IPPROTO_ICMPV6 ;#endifintdatalen = 56;/* data that goes with ICMP echo request */double rtt_min = INFINITY, rtt_max = -INFINITY, rtt_total = 0, rtt_sqr_total = 0;long long send_count = 0, recv_count = 0;int ttl_flag = 0, broadcast_flag = 0;int ttl = 0;struct timeval tval_start;const char *usage = usage: ping -v -h -b -t ttl -q n t-vtNormal moden t-btBroadcastn t-t ttltSet TTL(0-255)n t-qtQuiet mode;int main(int argc, char *argv)intc;struct addrinfo*ai;opterr = 0;/* dont want getopt() writing to stderr */while ( (c = getopt(argc, argv, vhbt:q) != -1) switch (c) case v:verbose+;break;case h: puts(usage); return 0;case b: broadcast_flag = 1; break;case t: ttl_flag = sscanf(optarg, %d, &ttl) & ttl = 0 & ttl ai_canonname, Sock_ntop_host(ai-ai_addr, ai-ai_addrlen), datalen);/* 4initialize according to protocol */if (ai-ai_family = AF_INET) pr = &proto_v4;#ifdefIPV6 else if (ai-ai_family = AF_INET6) pr = &proto_v6;if (IN6_IS_ADDR_V4MAPPED(&(struct sockaddr_in6 *) ai-ai_addr)-sin6_addr)err_quit(cannot ping IPv4-mapped IPv6 address);#endif elseerr_quit(unknown address family %d, ai-ai_family);pr-sasend = ai-ai_addr;pr-sarecv = calloc(1, ai-ai_addrlen);pr-salen = ai-ai_addrlen; gettimeofday(&tval_start, NULL);readloop();exit(0);void proc_v4(char *ptr, ssize_t len, struct timeval *tvrecv)inthlen1, icmplen;doublertt;struct ip*ip;struct icmp*icmp;struct timeval*tvsend;ip = (struct ip *) ptr;/* start of IP header */hlen1 = ip-ip_hl 2;/* length of IP header */icmp = (struct icmp *) (ptr + hlen1);/* start of ICMP header */if ( (icmplen = len - hlen1) 8)err_quit(icmplen (%d) icmp_type = ICMP_ECHOREPLY) if (icmp-icmp_id != pid)return;/* not a response to our ECHO_REQUEST */if (icmplen 16)err_quit(icmplen (%d) icmp_data;tv_sub(tvrecv, tvsend);rtt = tvrecv-tv_sec * 1000.0 + tvrecv-tv_usec / 1000.0;if (rtt rtt_max) rtt_max = rtt;rtt_total += rtt;rtt_sqr_total += rtt * rtt;recv_count+;if (verbose 0)printf(%d bytes from %s: seq=%u, ttl=%d, rtt=%.3f msn,icmplen, Sock_ntop_host(pr-sarecv, pr-salen),icmp-icmp_seq, ip-ip_ttl, rtt); else if (verbose 1) printf( %d bytes from %s: type = %d, code = %dn,icmplen, Sock_ntop_host(pr-sarecv, pr-salen),icmp-icmp_type, icmp-icmp_code);void proc_v6(char *ptr, ssize_t len, struct timeval* tvrecv)#ifdefIPV6inthlen1, icmp6len;doublertt;struct ip6_hdr*ip6;struct icmp6_hdr*icmp6;struct timeval*tvsend;ip6 = (struct ip6_hdr *) ptr;/* start of IPv6 header */hlen1 = sizeof(struct ip6_hdr);if (ip6-ip6_nxt != IPPROTO_ICMPV6)err_quit(next header not IPPROTO_ICMPV6);icmp6 = (struct icmp6_hdr *) (ptr + hlen1);if ( (icmp6len = len - hlen1) 8)err_quit(icmp6len (%d) icmp6_type = ICMP6_ECHO_REPLY) if (icmp6-icmp6_id != pid)return;/* not a response to our ECHO_REQUEST */if (icmp6len 16)err_quit(icmp6len (%d) tv_sec * 1000.0 + tvrecv-tv_usec / 1000.0;if (rtt rtt_max) rtt_max = rtt;rtt_total += rtt;rtt_sqr_total += rtt * rtt;recv_count+;if (verbose 0)printf(%d bytes from %s: seq=%u, hlim=%d, rtt=%.3f msn,icmp6len, Sock_ntop_host(pr-sarecv, pr-salen),icmp6-icmp6_seq, ip6-ip6_hlim, rtt); else if (verbose 1) printf( %d bytes from %s: type = %d, code = %dn,icmp6len, Sock_ntop_host(pr-sarecv, pr-salen),icmp6-icmp6_type, icmp6-icmp6_code);#endif/* IPV6 */unsigned short in_cksum(unsigned short *addr, int len) int nleft = len; int sum = 0; unsigned short *w = addr; unsigned short answer = 0; while (nleft 1) sum += *w+; nleft -= 2; /* 4mop up an odd byte, if necessary */ if (nleft = 1) *(unsigned char *)(&answer) = *(unsigned char *)w ; sum += answer; /* 4add back carry outs from top 16 bits to low 16 bits */ sum = (sum 16) + (sum & 0xffff); /* add hi 16 to low 16 */ sum += (sum 16); /* add carry */ answer = sum; /* truncate to 16 bits */ return(answer);void send_v4(void)intlen;struct icmp*icmp;icmp = (struct icmp *) sendbuf;icmp-icmp_type = ICMP_ECHO;icmp-icmp_code = 0;icmp-icmp_id = pid;icmp-icmp_seq = nsent+;gettimeofday(struct timeval *) icmp-icmp_data, NULL);len = 8 + datalen;/* checksum ICMP header and data */icmp-icmp_cksum = 0;icmp-icmp_cksum = in_cksum(u_short *) icmp, len);sendto(sockfd, sendbuf, len, 0, pr-sasend, pr-salen);void send_v6()#ifdefIPV6intlen;struct icmp6_hdr*icmp6;icmp6 = (struct icmp6_hdr *) sendbuf;icmp6-icmp6_type = ICMP6_ECHO_REQUEST;icmp6-icmp6_code = 0;icmp6-icmp6_id = pid;icmp6-icmp6_seq = nsent+;gettimeofday(struct timeval *) (icmp6 + 1), NULL);len = 8 + datalen;/* 8-byte ICMPv6 header */sendto(sockfd, sendbuf, len, 0, pr-sasend, pr-salen);#endif/* IPV6 */void readloop(void)intsize;charrecvbufBUFSIZE;socklen_tlen;ssize_tn;struct timevaltval;sockfd = socket(pr-sasend-sa_family, SOCK_RAW, pr-icmpproto);setuid(getuid();/* dont need special permissions any more */size = 60 * 1024;/* OK if setsockopt fails */setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size);if (ttl_flag) setsockopt(sockfd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl) ; if (broadcast_flag) setsockopt(sockfd, SOL_SOCKET, SO_BROADCAST, &broadcast_flag, sizeof(broadcast_flag) ;sig_alrm(SIGALRM);/* send first packet */for ( ; ; ) len = pr-salen;n = recvfrom(sockfd, recvbuf, sizeof(recvbuf), 0, pr-sarecv, &len);if (n fproc)(recvbuf, n, &tval);void sig_alrm(int signo) (*pr-fsend)(); send_count+; alarm(1); return; /* probably interrupts recvfrom() */void sig_int(int signo) struct timeval tval_end; double tval_total; gettimeofday(&tval_end, NULL); tv_sub(&tval_end, &tval_start); tval_total = tval_end.tv_sec * 1000.0 + tval_end.tv_usec / 1000.0; puts(- ping statistics -); printf(%lld packets transmitted, %lld received, %.0lf% packet loss, time %.2lfmsn, send_count, recv_count, (send_count - recv_count) * 100.0 / send_count, tval_total); double rtt_avg = rtt_total / recv_count; printf(rtt min/avg/max/mdev = %.3lf/%.3lf/%.3lf/%.3lf msn, rtt_min, rtt_avg, rtt_max, rtt_sqr_total / recv_count - rtt_avg * rtt_avg); close(sockfd); exit(0);void tv_sub(struct timeval *out, struct timeval *in)if ( (out-tv_usec -= in-tv_usec) tv_sec;out-tv_usec += ;out-tv_sec -= in-tv_sec;char * sock_ntop_host(const struct sockaddr *sa, socklen_t salen) static char str128; /* Unix domain is largest */ switch (sa-sa_family) case AF_INET: struct sockaddr_in *sin = (struct sockaddr_in *) sa; if (inet_ntop(AF_INET, &sin-sin_addr, str, sizeof(str) = NULL) return(NULL); return(str); #ifdef IPV6 case AF_INET6: struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) sa; if (inet_ntop(AF_INET6, &sin6-sin6_addr, str, sizeof(str) = NULL) return(NULL); return(str); #endif#ifdef HAVE_SOCKADDR_DL_STRUCT case AF_LINK: struct sockaddr_dl *sdl = (struct sockaddr_dl *) sa; if (sdl-sdl_nlen 0) snprintf(str, sizeof(str), %*s, sdl-sdl_nlen, &sdl-sdl_data0); else snprintf(str, sizeof(str), AF_LINK, index=%d, sdl-sdl_index); return(str); #endif default: snprintf(str, sizeof(str), sock_ntop_host: unknown AF_xxx: %d, len %d, sa-sa_family, salen); return(str); return (NULL);char * Sock_ntop_host(const struct sockaddr *sa, socklen_t salen) char *ptr; if ( (ptr = sock_ntop_host(sa, salen) = NULL) err_sys(sock_ntop_host error); /* inet_ntop() sets errno */ return(ptr