1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
/*
* Copyright (C) 2014-2020 Firejail Authors
*
* This file is part of firejail project
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "fnet.h"
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/if_ether.h> //TCP/IP Protocol Suite for Linux
#include <net/if.h>
#include <netinet/in.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/tcp.h>
#include <linux/if_packet.h>
typedef struct arp_hdr_t {
uint16_t htype;
uint16_t ptype;
uint8_t hlen;
uint8_t plen;
uint16_t opcode;
uint8_t sender_mac[6];
uint8_t sender_ip[4];
uint8_t target_mac[6];
uint8_t target_ip[4];
} ArpHdr;
// scan interface (--scan option)
void arp_scan(const char *dev, uint32_t ifip, uint32_t ifmask) {
assert(dev);
assert(ifip);
// printf("Scanning interface %s (%d.%d.%d.%d/%d)\n",
// dev, PRINT_IP(ifip & ifmask), mask2bits(ifmask));
if (strlen(dev) > IFNAMSIZ) {
fprintf(stderr, "Error: invalid network device name %s\n", dev);
exit(1);
}
// find interface mac address
int sock;
if ((sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0)
errExit("socket");
struct ifreq ifr;
memset(&ifr, 0, sizeof (ifr));
strncpy(ifr.ifr_name, dev, IFNAMSIZ - 1);
if (ioctl(sock, SIOCGIFHWADDR, &ifr) < 0)
errExit("ioctl");
close(sock);
uint8_t mac[6];
memcpy (mac, ifr.ifr_hwaddr.sa_data, 6);
// open layer2 socket
if ((sock = socket(PF_PACKET, SOCK_RAW, htons (ETH_P_ALL))) < 0)
errExit("socket");
// try all possible ip addresses in ascending order
uint32_t range = ~ifmask + 1; // the number of potential addresses
// this software is not supported for /31 networks
if (range < 4) {
fprintf(stderr, "Warning: this option is not supported for /31 networks\n");
close(sock);
return;
}
uint32_t dest = (ifip & ifmask) + 1;
uint32_t last = dest + range - 1;
uint32_t src = htonl(ifip);
// wait not more than one second for an answer
int header_printed = 0;
uint32_t last_ip = 0;
struct timeval ts;
ts.tv_sec = 2; // 2 seconds receive timeout
ts.tv_usec = 0;
while (1) {
fd_set rfds;
FD_ZERO(&rfds);
FD_SET(sock, &rfds);
fd_set wfds;
FD_ZERO(&wfds);
FD_SET(sock, &wfds);
int maxfd = sock;
uint8_t frame[ETH_FRAME_LEN]; // includes eht header, vlan, and crc
memset(frame, 0, ETH_FRAME_LEN);
int nready;
if (dest < last)
nready = select(maxfd + 1, &rfds, &wfds, (fd_set *) 0, NULL);
else
nready = select(maxfd + 1, &rfds, (fd_set *) 0, (fd_set *) 0, &ts);
if (nready < 0)
errExit("select");
if (nready == 0) { // timeout
break;
}
if (FD_ISSET(sock, &wfds) && dest < last) {
// configure layer2 socket address information
struct sockaddr_ll addr;
memset(&addr, 0, sizeof(addr));
if ((addr.sll_ifindex = if_nametoindex(dev)) == 0)
errExit("if_nametoindex");
addr.sll_family = AF_PACKET;
memcpy (addr.sll_addr, mac, 6);
addr.sll_halen = ETH_ALEN;
// build the arp packet header
ArpHdr hdr;
memset(&hdr, 0, sizeof(hdr));
hdr.htype = htons(1);
hdr.ptype = htons(ETH_P_IP);
hdr.hlen = 6;
hdr.plen = 4;
hdr.opcode = htons(1); //ARPOP_REQUEST
memcpy(hdr.sender_mac, mac, 6);
memcpy(hdr.sender_ip, (uint8_t *)&src, 4);
uint32_t dst = htonl(dest);
memcpy(hdr.target_ip, (uint8_t *)&dst, 4);
// build ethernet frame
uint8_t frame[ETH_FRAME_LEN]; // includes eht header, vlan, and crc
memset(frame, 0, sizeof(frame));
frame[0] = frame[1] = frame[2] = frame[3] = frame[4] = frame[5] = 0xff;
memcpy(frame + 6, mac, 6);
frame[12] = ETH_P_ARP / 256;
frame[13] = ETH_P_ARP % 256;
memcpy (frame + 14, &hdr, sizeof(hdr));
// send packet
int len;
if ((len = sendto (sock, frame, 14 + sizeof(ArpHdr), 0, (struct sockaddr *) &addr, sizeof (addr))) <= 0)
errExit("send");
//printf("send %d bytes to %d.%d.%d.%d\n", len, PRINT_IP(dest));
fflush(0);
dest++;
}
if (FD_ISSET(sock, &rfds)) {
// read the incoming packet
int len = recvfrom(sock, frame, ETH_FRAME_LEN, 0, NULL, NULL);
if (len < 0) {
perror("recvfrom");
}
// parse the incoming packet
if ((unsigned int) len < 14 + sizeof(ArpHdr))
continue;
// look only at ARP packets
if (frame[12] != (ETH_P_ARP / 256) || frame[13] != (ETH_P_ARP % 256))
continue;
ArpHdr hdr;
memcpy(&hdr, frame + 14, sizeof(ArpHdr));
if (hdr.opcode == htons(2)) {
// check my mac and my address
if (memcmp(mac, hdr.target_mac, 6) != 0)
continue;
uint32_t ip;
memcpy(&ip, hdr.target_ip, 4);
if (ip != src)
continue;
memcpy(&ip, hdr.sender_ip, 4);
ip = ntohl(ip);
if (ip == last_ip) // filter duplicates
continue;
last_ip = ip;
// printing
if (header_printed == 0) {
fmessage(" Network scan:\n");
header_printed = 1;
}
fmessage(" %02x:%02x:%02x:%02x:%02x:%02x\t%d.%d.%d.%d\n",
PRINT_MAC(hdr.sender_mac), PRINT_IP(ip));
}
}
}
close(sock);
}
|
