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
|
/*
* $Id: tcplog.c,v 1.7 2001/02/19 10:06:17 ams Exp $
* Copyright 1998-2001 Abhijit Menon-Sen <ams@wiw.org>
*/
#include <string.h>
#include "tcplog.h"
/* getservbyport(3) wrapper */
char *service(int port)
{
struct servent *serv;
static char name[32];
serv = getservbyport(htons(port), "tcp");
if (serv == (struct servent*)NULL) {
snprintf(name, 32, "port %d", port);
}
else {
snprintf(name, 32, "%s", serv->s_name);
}
return (name);
}
/* parse configuration file */
void configure(char *file)
{
char buf[MAXLINE], *keyword, *name, *map;
FILE *rc;
int port = 0, level;
struct ex *curr = &root, *next = (struct ex *)NULL;
struct servent *serv;
/* use default configuration if none is specified */
if (file == (char *)NULL) { file = cfgfile; }
if ((rc = fopen(file, "r")) == (FILE *)NULL) {
perror(file);
return;
}
while (fgets(buf, MAXLINE-1, rc)) {
/* ignore comments and blank lines */
if (buf[0] == '#' || buf[0] == '\n') { continue; }
keyword = strtok(buf, " \t");
/* default log level */
if (strcasecmp(keyword, "level") == 0) {
lvl = loglevel(strtok((char *)NULL, " \t\n"));
continue;
}
/* logging facility */
if (strcasecmp(keyword, "facility") == 0) {
fac = facility(strtok((char *)NULL, " \t\n"));
continue;
}
/* list of hosts to ignore */
if (strcasecmp(keyword, "except") == 0) {
while ((name = strtok((char *)NULL, " \t\n,")) != (char *)NULL) {
/* add to list */
curr->host = (char *)malloc(strlen(name)+1);
if (curr->host == (char *)NULL) {
fprintf(stderr, "malloc() failed.\n");
exit(-1);
}
strcpy(curr->host, name);
next = (struct ex *)malloc(sizeof(struct ex));
if (next == (struct ex *)NULL) {
fprintf(stderr, "malloc() failed.\n");
exit(-1);
}
curr->link = next;
curr = next;
curr->link = (struct ex *)NULL;
}
continue;
}
/* service name/port */
if (isdigit(keyword[0])) {
/* port number */
port = strtol(keyword, (char **)NULL, 0);
level = loglevel(strtok((char *)NULL, " \t\n"));
}
else {
/* service name */
serv = getservbyname(keyword, "tcp");
if (serv != (struct servent *)NULL) {
port = ntohs(serv->s_port);
level = loglevel(strtok((char *)NULL, " \t\n"));
}
else {
fprintf(stderr, "%s: unknown service\n", keyword);
continue;
}
}
if (port) {
/* add to magical two-level 1024-way port tree */
if (ports[port >> 6] == (char *)NULL) {
map = (char *)malloc(64);
if (map == (char *)NULL) {
fprintf(stderr, "malloc() failed.\n");
exit(-1);
}
memset(map, lvl, 64);
ports[port >> 6] = map;
}
ports[port >> 6][port & 0x3f] = level;
}
}
}
int main(int argc, char *argv[])
{
char *rc = (char *)NULL, *host;
int s = 0, c = 0, index = 0, level = lvl, p;
tcppkt *pkt;
/* process command line parameters */
while (1) {
c = getopt_long(argc, argv, "f:nlv", par, &index);
if (c == -1) { break; }
switch (c) {
case 0: switch (index) {
case 0: rc = optarg;
break;
case 1: resolve_names = 0;
break;
case 2: printf("%s\n", version);
exit(0);
break;
}
break;
case 'f': rc = optarg;
break;
case 'n': resolve_names = 0;
break;
case 'v': printf("%s\n", version);
exit(0);
break;
default : printf ("options: --file, --no-resolve, --version\n");
exit(0);
}
}
/* need root to bind raw socket */
if (geteuid() != 0) {
fprintf(stderr, "%s: root privileges required.\n", argv[0]);
exit(-1);
}
configure(rc);
background();
if ((s = socket(AF_INET, SOCK_RAW, IPPROTO_TCP)) < 0) {
perror("socket");
exit(1);
}
if ((pkt = (tcppkt *)malloc(MTU)) == (tcppkt *)NULL) {
fprintf(stderr, "malloc() failed\n");
exit(-1);
}
openlog("tcplog", 0, fac);
syslog(LOG_INFO, "started");
while (1) {
/* process packets */
read(s, pkt, MTU);
/* only log connection requests */
if (pkt->tcp.syn && !pkt->tcp.ack) {
host = gethost(pkt->ip.saddr);
if (excepted(pkt->ip.saddr, host)) { continue; }
if (pkt->ip.ihl != 5) {
/* pkt->ip.ihl < 5 should NEVER happen */
continue;
}
p = ntohs(pkt->tcp.dest);
/* find log level from magical tree */
level = ports[p >> 6] == (char *)NULL?
lvl : ports[p >> 6][p & 0x3f];
if (ntohs(pkt->tcp.source) == 20 && p < 1024) {
syslog(LOG_WARNING, "FTPbounce (%s) from %s", service(p), host);
continue;
}
if (level) {
syslog(level, "%s request from %s", service(p), host);
}
}
}
}
|
