1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <unistd.h> 4 #include <time.h> 5 #include <arpa/inet.h> 6 7 #include <libmnl/libmnl.h> 8 #include <libnetfilter_conntrack/libnetfilter_conntrack.h> 9 10 #include <linux/netfilter/nf_conntrack_tcp.h> 11 12 static int data_cb(const struct nlmsghdr *nlh, void *data) 13 { 14 struct nf_conntrack *ct; 15 char buf[4096]; 16 17 ct = nfct_new(); 18 if (ct == NULL) 19 return MNL_CB_OK; 20 21 nfct_nlmsg_parse(nlh, ct); 22 23 nfct_snprintf(buf, sizeof(buf), ct, NFCT_T_UNKNOWN, NFCT_O_DEFAULT, 0); 24 printf("%s\n", buf); 25 26 nfct_destroy(ct); 27 28 return MNL_CB_OK; 29 } 30 31 int main(void) 32 { 33 struct mnl_socket *nl; 34 struct nlmsghdr *nlh; 35 struct nfgenmsg *nfh; 36 char buf[MNL_SOCKET_BUFFER_SIZE]; 37 unsigned int seq, portid; 38 struct nf_conntrack *ct; 39 int ret; 40 41 nl = mnl_socket_open(NETLINK_NETFILTER); 42 if (nl == NULL) { 43 perror("mnl_socket_open"); 44 exit(EXIT_FAILURE); 45 } 46 47 if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) { 48 perror("mnl_socket_bind"); 49 exit(EXIT_FAILURE); 50 } 51 portid = mnl_socket_get_portid(nl); 52 53 nlh = mnl_nlmsg_put_header(buf); 54 nlh->nlmsg_type = (NFNL_SUBSYS_CTNETLINK << 8) | IPCTNL_MSG_CT_GET; 55 nlh->nlmsg_flags = NLM_F_REQUEST|NLM_F_ACK; 56 nlh->nlmsg_seq = seq = time(NULL); 57 58 nfh = mnl_nlmsg_put_extra_header(nlh, sizeof(struct nfgenmsg)); 59 nfh->nfgen_family = AF_INET; 60 nfh->version = NFNETLINK_V0; 61 nfh->res_id = 0; 62 63 ct = nfct_new(); 64 if (ct == NULL) { 65 perror("nfct_new"); 66 return 0; 67 } 68 69 nfct_set_attr_u8(ct, ATTR_L3PROTO, AF_INET); 70 nfct_set_attr_u32(ct, ATTR_IPV4_SRC, inet_addr("1.1.1.1")); 71 nfct_set_attr_u32(ct, ATTR_IPV4_DST, inet_addr("2.2.2.2")); 72 73 nfct_set_attr_u8(ct, ATTR_L4PROTO, IPPROTO_TCP); 74 nfct_set_attr_u16(ct, ATTR_PORT_SRC, htons(20)); 75 nfct_set_attr_u16(ct, ATTR_PORT_DST, htons(10)); 76 77 nfct_nlmsg_build(nlh, ct); 78 79 ret = mnl_socket_sendto(nl, nlh, nlh->nlmsg_len); 80 if (ret == -1) { 81 perror("mnl_socket_recvfrom"); 82 exit(EXIT_FAILURE); 83 } 84 85 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); 86 while (ret > 0) { 87 ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL); 88 if (ret <= MNL_CB_STOP) 89 break; 90 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf)); 91 } 92 if (ret == -1) { 93 perror("mnl_socket_recvfrom"); 94 exit(EXIT_FAILURE); 95 } 96 97 mnl_socket_close(nl); 98 99 return 0; 100 } 101
