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--- arpwatch-2.1a10/arpwatch.c Sat Oct 14 05:07:35 2000
+++ arpwatch-2.1a10/arpwatch.c Sun Jun 10 16:22:57 2001
@@ -62,7 +62,7 @@
#include <string.h>
#include <syslog.h>
#include <unistd.h>
-
+#include <pwd.h>
#include <pcap.h>
#include "gnuc.h"
@@ -141,6 +141,25 @@
int sanity_fddi(struct fddi_header *, struct ether_arp *, int);
__dead void usage(void) __attribute__((volatile));
+void dropprivileges(const char* user)
+{
+ struct passwd* pw;
+ pw = getpwnam( user );
+ if ( pw ) {
+ if ( initgroups(pw->pw_name, NULL) != 0 || setgid(pw->pw_gid) != 0 ||
+ setuid(pw->pw_uid) != 0 ) {
+ syslog(LOG_ERR, "Couldn't change to '%.32s' uid=%d gid=%d", user,
+ pw->pw_uid, pw->pw_gid);
+ exit(1);
+ }
+ }
+ else {
+ syslog(LOG_ERR, "Couldn't find user '%.32s' in /etc/passwd", user);
+ exit(1);
+ }
+ syslog(LOG_DEBUG, "Running as uid=%d gid=%d", getuid(), getgid());
+}
+
int
main(int argc, char **argv)
{
@@ -153,6 +172,7 @@
register char *interface, *rfilename;
struct bpf_program code;
char errbuf[PCAP_ERRBUF_SIZE];
+ char* serveruser = NULL;
if (argv[0] == NULL)
prog = "arpwatch";
@@ -170,7 +190,7 @@
interface = NULL;
rfilename = NULL;
pd = NULL;
- while ((op = getopt(argc, argv, "df:i:n:Nr:")) != EOF)
+ while ((op = getopt(argc, argv, "df:i:n:Nr:u:")) != EOF)
switch (op) {
case 'd':
@@ -202,6 +222,16 @@
rfilename = optarg;
break;
+ case 'u':
+ if ( optarg ) {
+ serveruser = strdup(optarg);
+ }
+ else {
+ fprintf(stderr, "%s: Need username after -u\n", prog);
+ usage();
+ }
+ break;
+
default:
usage();
}
@@ -283,8 +313,11 @@
* Revert to non-privileged user after opening sockets
* (not needed on most systems).
*/
- setgid(getgid());
- setuid(getuid());
+ /*setgid(getgid());*/
+ /*setuid(getuid());*/
+ if ( serveruser ) {
+ dropprivileges( serveruser );
+ }
/* Must be ethernet or fddi */
linktype = pcap_datalink(pd);
@@ -751,6 +784,6 @@
(void)fprintf(stderr, "Version %s\n", version);
(void)fprintf(stderr, "usage: %s [-dN] [-f datafile] [-i interface]"
- " [-n net[/width]] [-r file]\n", prog);
+ " [-n net[/width]] [-r file] [-u username]\n", prog);
exit(1);
}
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