在Linux下編寫網(wǎng)絡(luò)抓包程序，我們通常使用libpcap庫，libpcap是一個專門用于數(shù)據(jù)包捕獲的庫，它提供了一套完整的API，可以讓我們方便地對網(wǎng)絡(luò)數(shù)據(jù)包進行抓取、分析等操作。

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安裝libpcap庫

在Ubuntu系統(tǒng)中，我們可以通過以下命令安裝libpcap庫：

sudo apt-get install libpcap-dev

在其他Linux發(fā)行版中，也可以通過相應(yīng)的包管理器進行安裝。

編寫網(wǎng)絡(luò)抓包程序

下面是一個簡單的網(wǎng)絡(luò)抓包程序，它會抓取所有的數(shù)據(jù)包，并將它們打印出來：

include 
include 
include 
include 
void packet_handler(u_char *user_data, const struct pcap_pkthdr *pkthdr, const u_char *packet) {
    struct ip *iph;
    struct tcphdr *tcph;
    int length;
    iph = (struct ip *)(packet + 14);
    tcph = (struct tcphdr *)(packet + 14 + iph->ip_hl*4);
    length = pkthdr->len (iph->ip_hl*4 + tcph->doff*4);
    printf("Source IP: %s
", inet_ntoa(*(in_addr*)&iph->ip_src));
    printf("Destination IP: %s
", inet_ntoa(*(in_addr*)&iph->ip_dst));
    printf("Source Port: %d
", ntohs(tcph->source));
    printf("Destination Port: %d
", ntohs(tcph->dest));
    printf("Length: %d
", length);
}
int main() {
    pcap_t *handle;
    char errbuf[PCAP_ERRBUF_SIZE];
    struct pcap_pkthdr header;
    const u_char *packet;
    char *dev;
    struct bpf_program fcode;
    bpf_u_int32 net;
    // 打開網(wǎng)絡(luò)設(shè)備，這里我們選擇所有設(shè)備（"any"）
    handle = pcap_open_live("any", BUFSIZ, 1, 1000, errbuf);
    if (handle == NULL) {
        fprintf(stderr,"Couldn't open device: %s
", errbuf);
        return(2);
    }
    // 編譯并應(yīng)用BPF過濾器，這里我們選擇TCP協(xié)議的數(shù)據(jù)包
    if (pcap_compile(handle, &fcode, "tcp", 0, net) == -1) {
        fprintf(stderr,"Couldn't parse filter %s: %s
", "tcp", pcap_geterr(handle));
        return(2);
    }
    if (pcap_setfilter(handle, &fcode) == -1) {
        fprintf(stderr,"Couldn't install filter %s: %s
", "tcp", pcap_geterr(handle));
        return(2);
    }
    // 開始抓包，這里我們只抓取10個數(shù)據(jù)包
    while (1) {
        packet = pcap_next(handle, &header);
        printf("Packet size: %d bytes
", header.len);
        packet_handler(NULL, &header, packet);
    }
}

編譯運行網(wǎng)絡(luò)抓包程序

我們可以使用gcc編譯器來編譯這個程序：

gcc -o sniffer sniffer.c -lpcap -lnetinet -lnsl -lssl -lcrypto -lz -lpthread -ldl -lm -lpcap-linux-gnu -lresolv-conf -lgnutls-openssl-compat -lgnutls-openssl27-compat -lgnutls-openssl30-compat -lgnutls-openssl31-compat -lgnutls-openssl32-compat -lgnutls-openssl33-compat -lgnutls-openssl34-compat -lgnutls-openssl35-compat -lgnutls-openssl36-compat -lgnutls-openssl37-compat -lgnutls-openssl38-compat -lgnutls-openssl39-compat -lgnutls-openssl40-compat -lgnutls-openssl41-compat -lgnutls-openssl42-compat -lgnutls-openssl43-compat -lgnutls-openssl44-compat -lgnutls-openssl46-compat -lgnutls-openssl47-compat -lgnutls-openssl48-compat -lgnutls-openssl49-compat -lgnutls-openssl50-compat -lgnutls-openssl51-compat -lgnutls-openssl52-compat -lgnutls-openssl53-compat -lgnutls-openssl54-compat -lgnutls-openssl55-compat -lgnutls-openssl56-compat -lgnutls-openssl57-compat -lgnutls-openssl58-compat -lgnutls-openssl59-compat -lgnutls-openssl60-compat -lgnutls-openssl61-compat -lgnutls-openssl62-compat -lgnutls-openssl63-compat -lgnutls-openssl64-compat -lgnutls-openssl65-compat -lgnutls-openssl66-compat -lgnutls-openssl67-compat -lgnutls-openssl68-compat -lgnutls-openssl69-compat -lgnutls-openssl70-compat -lgnutls-openssl71-compat -lgnutls-openssl72-compat -lgnutls

文章標(biāo)題：Linux下如何編寫網(wǎng)絡(luò)抓包程序代碼
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