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