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ipv6mon.c
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/*
* ipv6mon v1.0: An IPv6 Address Monitoring Tool
*
* Copyright (C) 2011-2012 Fernando Gont
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*
*
* Build with: gcc ipv6mon.c -Wall -lpcap -o ipv6mon
*
* This program has been tested to compile and run on: FreeBSD 9.0,
* NetBSD 5.1, OpenBSD 4.9, and Linux 2.6.38-10. It requires that the
* libpcap library be installed on your system.
*
* Please send any bug reports to Fernando Gont <fgont@si6networks.com>
*/
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <grp.h>
#include <ifaddrs.h>
#include <net/if.h>
#include <netinet/icmp6.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <pcap.h>
#include <pwd.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#ifdef __linux__
#include <netpacket/packet.h>
#elif defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__APPLE__)
#include <net/if_dl.h>
#endif
#include "ipv6mon.h"
#include <syslog.h>
/* Function prototypes */
int init_iface_data(struct iface_data *);
int init_host_list(struct host_list *);
int insert_pad_opt(unsigned char *ptrhdr, const unsigned char *, unsigned int);
void usage(void);
void print_help(void);
int ether_pton(const char *, struct ether_addr *, unsigned int);
int ether_ntop(const struct ether_addr *, char *, size_t);
u_int16_t in_chksum(void *, void *, size_t);
unsigned int match_ipv6(struct in6_addr *, u_int8_t *, unsigned int, struct in6_addr *);
unsigned int match_ether(struct ether_addr *, unsigned int, struct ether_addr *);
void sanitize_ipv6_prefix(struct in6_addr *, u_int8_t);
void randomize_ipv6_addr(struct in6_addr *, struct in6_addr *, u_int8_t);
void randomize_ether_addr(struct ether_addr *);
void ether_to_ipv6_linklocal(struct ether_addr *etheraddr, struct in6_addr *ipv6addr);
void generate_slaac_address(struct in6_addr *, struct ether_addr *, struct in6_addr *);
int is_eq_in6_addr(struct in6_addr *, struct in6_addr *);
struct in6_addr solicited_node(const struct in6_addr *);
struct ether_addr ether_multicast(const struct in6_addr *);
int match_ipv6_to_prefixes(struct in6_addr *, struct in6_addr *, unsigned char *, unsigned int);
int process_router_advert(struct iface_data *, struct pcap_pkthdr *, const u_char *);
int validate_host_entries(pcap_t *, struct iface_data *, struct host_list *, struct host_list *);
int create_candidate_andress(struct iface_data *, struct host_list *, struct host_entry *);
void free_host_entries(struct host_list *);
int send_multicast_probe(pcap_t *, struct iface_data *, struct host_list *, unsigned char);
int probe_node_nd(const char *, struct ether_addr *, struct in6_addr *, struct in6_addr *, struct ether_addr *);
struct host_entry *is_ip6_in_list(struct host_list *, struct in6_addr *);
int is_ip6_in_prefix_list(struct in6_addr *, struct prefix_list *);
int is_ip6_in_address_list(struct prefix_list *, struct in6_addr *);
struct prefix_entry *lookup_ip6_in_address_list(struct prefix_list *, struct in6_addr *);
int send_neighbor_advert(struct iface_data *, pcap_t *, const u_char *);
int send_router_solicit(pcap_t *, struct iface_data *);
int process_icmp6_response(struct iface_data *, struct host_list *, unsigned char, struct pcap_pkthdr *, const u_char *,
unsigned char *);
int valid_icmp6_response(struct iface_data *, struct host_list *, struct pcap_pkthdr *, const u_char *);
int process_host_entries(pcap_t *, struct iface_data *, struct host_list *);
int get_if_addrs(struct iface_data *);
int check_local_addresses(struct iface_data *);
int send_host_probe(pcap_t *, struct iface_data *, unsigned char, struct host_entry *);
int gcollection_host_entries(struct iface_data *, struct host_list *);
struct host_entry *add_host_entry(struct host_list *, struct in6_addr *, struct ether_addr *);
int log_hentry(struct iface_data *, struct host_entry *, time_t *, unsigned char);
u_int16_t key(struct host_list *, struct in6_addr *);
struct in6_addr *src_addr_sel(struct iface_data *, struct in6_addr *);
int keyval(char *, unsigned int, char **, char **);
int process_config_file(const char *);
int make_daemon(void);
int already_running(void);
int log_start(struct iface_data *);
int log_stop(struct iface_data *);
void sigterm(int);
/* Host list */
struct host_list hlist;
/* Used for router discovery */
struct iface_data idata;
struct prefix_entry *prefix_ols[MAX_PREFIXES_ONLINK], *prefix_acs[MAX_PREFIXES_AUTO];
struct prefix_entry *prefix_local[MAX_LOCAL_ADDRESSES];
/* Variables used for learning the default router */
struct ether_addr router_ether, rs_ether;
struct in6_addr router_ipv6, rs_ipv6;
/* Data structures for packets read from the wire */
pcap_t *sfd;
struct pcap_pkthdr *pkthdr;
const u_char *pktdata;
unsigned char *pkt_end;
struct ether_header *pkt_ether;
struct ip6_hdr *pkt_ipv6;
struct in6_addr *pkt_ipv6addr;
unsigned int pktbytes;
struct bpf_program pcap_filter;
char dev[64], errbuf[PCAP_ERRBUF_SIZE];
unsigned char buffer[BUFFER_SIZE], buffrh[MIN_IPV6_HLEN + MIN_TCP_HLEN];
unsigned char wbuffer[BUFFER_SIZE];
unsigned char *v6buffer, *ptr, *startofprefixes;
char *pref;
char iface[IFACE_LENGTH];
struct ip6_hdr *ipv6;
struct icmp6_hdr *icmp6;
struct ether_header *ethernet;
struct ether_addr hsrcaddr, hdstaddr;
struct in6_addr srcaddr, dstaddr;
char *lasts, *rpref;
char *charptr;
size_t nw;
unsigned long ul_res, ul_val;
unsigned int i, j, startrand;
unsigned int skip;
unsigned char srcpreflen;
u_int16_t mask;
u_int8_t hoplimit;
char plinkaddr[ETHER_ADDR_PLEN];
char psrcaddr[INET6_ADDRSTRLEN], pdstaddr[INET6_ADDRSTRLEN], pv6addr[INET6_ADDRSTRLEN];
unsigned char verbose_f = 0, iface_f = 0, hsrcaddr_f = 0, probe_echo_f = 0, probe_unrec_f = 0, probe_f = 0;
unsigned char *prev_nh;
/* Configuration variables */
char *logfile, *lockfile, *unprivuser, *unprivgroup, *probestr, *configfile;
unsigned int timestampf, maxaddrentries, maxcandentries, addrtimeout, candaddrtimeout, maxunprobedint;
unsigned int unicastprobeint, mcechoprobeint, mcunrecprobeint;
unsigned char logfile_f = 0, lockfile_f = 0, unprivuser_f = 0, unprivgroup_f = 0, probetype_f = 0, timestampf_f = 0;
unsigned char maxaddrentries_f = 0, maxcandentries_f = 0, addrtimeout_f = 0, candaddrtimeout_f = 0;
unsigned char maxunprobedint_f = 0, unicastprobeint_f = 0, mcechoprobeint_f = 0, mcunrecprobeint_f = 0;
unsigned char configfile_f = 0, showconfig_f = 0, shutdown_f = 0;
/* For the log file */
FILE *fplog;
/* Used to store the all-nodes onlink address */
struct in6_addr all_nodes_onlink;
/* For I/O multiplexing */
fd_set rset, wset, eset;
/* Current time */
time_t curtime;
int main(int argc, char **argv) {
extern char *optarg;
extern int optind;
struct passwd *pwdptr;
struct group *grpptr;
fd_set sset;
int sel;
struct timeval timeout;
int result;
struct sigaction sa;
unsigned char error_f = 0;
struct host_entry *hptr;
struct ether_header *pkt_ether;
struct ip6_hdr *pkt_ipv6;
struct icmp6_hdr *pkt_icmp6;
struct nd_neighbor_solicit *pkt_ns;
unsigned char *pkt_end;
static struct option longopts[] = {{"config-file", required_argument, 0, 'c'},
{"show-config", no_argument, 0, 'q'},
{"verbose", no_argument, 0, 'v'},
{"help", no_argument, 0, 'h'}};
char shortopts[] = "c:qvh";
char option;
hoplimit = 255;
while ((option = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1) {
switch (option) {
case 'c': /* Configuration file */
if ((configfile = malloc(strlen(optarg) + 1)) == NULL) {
error_f = 1;
break;
}
strncpy(configfile, optarg, strlen(optarg) + 1);
configfile_f = 1;
break;
case 'q':
showconfig_f = 1;
break;
case 'v': /* Be verbose */
verbose_f++;
break;
case 'h': /* Help */
print_help();
exit(1);
break;
default:
usage();
exit(1);
break;
} /* switch */
} /* while(getopt) */
if (!showconfig_f)
openlog("ipv6mon", LOG_CONS, LOG_DAEMON);
if (error_f) {
if (showconfig_f)
puts("Error while allocating memory to store configuration file pathname");
else
syslog(LOG_ERR, "Error while allocating memory to store configuration file pathname");
exit(1);
}
if (geteuid()) {
if (showconfig_f)
puts("ipv6mon needs superuser privileges to run");
else
syslog(LOG_ERR, "ipv6mon needs superuser privileges to run");
exit(1);
}
if (!configfile_f) {
configfile = "/etc/ipv6mon.conf";
}
if (process_config_file(configfile) == -1)
exit(1);
if (init_iface_data(&idata) != 0) {
if (showconfig_f)
puts("Error initializing internal idata structure");
else
syslog(LOG_ERR, "Error initializing internal idata structure");
exit(1);
}
if (init_host_list(&hlist) != 0) {
if (showconfig_f)
puts("Error initializing internal host_list structure");
else
syslog(LOG_ERR, "Error initializing internal host_list structure");
exit(1);
}
if (!iface_f) {
if (showconfig_f)
puts("Must specify the network interface with the 'NetworkInterface' variable");
else
syslog(LOG_ERR, "Network Interface card not specified");
exit(1);
}
if (showconfig_f) {
if (probe_echo_f) {
if (probe_unrec_f)
probestr = "all";
else
probestr = "echo";
}
else
probestr = "unrec";
printf("NetworkInterface: %s\n", idata.iface);
printf("AddressLogFile: %s\n", logfile);
printf("LockFile: %s\n", lockfile);
printf("UnprivilegedUser: %s\n", unprivuser);
printf("UnprivilegedGroup: %s\n", unprivgroup);
printf("TimestampFormat: %s\n", (timestampf == TIMESTAMP_DATE) ? "date" : "epoch");
printf("MaxAddressEntries: %u\n", maxaddrentries);
printf("MaxCandidateEntries: %u\n", maxcandentries);
printf("AddressTimeout: %u\n", addrtimeout);
printf("CandidateAddressTimeout: %u\n", candaddrtimeout);
printf("MaxUnprobedInterval: %u\n", maxunprobedint);
printf("UnicastProbeInterval: %u\n", unicastprobeint);
printf("McastEchoProbeInterval: %u\n", mcechoprobeint);
printf("McastUnrecProbeInterval: %u\n", mcunrecprobeint);
printf("ProbeType: %s\n", probestr);
exit(0);
}
/*
We close the file descriptor for syslog. make_daemon() will close all open descriptors, and open
a new one for syslog()
*/
closelog();
if (make_daemon() == -1) {
syslog(LOG_ERR, "Failed when trying to become daemon");
exit(1);
}
if ((result = already_running()) == 1) {
syslog(LOG_ERR, "Another instance of ipv6mon is already running");
exit(5);
}
else if (result == -1) {
syslog(LOG_ERR, "Error in already running():");
exit(1);
}
/* Log file should be rw for the owner, readable by the group, with no access to others */
umask(S_IWGRP | S_IXGRP | S_IROTH | S_IWOTH | S_IXOTH);
if ((fplog = fopen(logfile, "a")) == NULL) {
syslog(LOG_ERR, "Error opening logfile (%m)");
exit(1);
}
if ((sfd = pcap_open_live(idata.iface, PCAP_SNAP_LEN, PCAP_PROMISC, PCAP_TIMEOUT, errbuf)) == NULL) {
syslog(LOG_ERR, "Opening pcap device: %s", errbuf);
return (-1);
}
if (pcap_datalink(sfd) != DLT_EN10MB) {
syslog(LOG_ERR, "Interface '%s' is not of supported interface types", iface);
return (-1);
}
/*
We to setuid() to UnprivilegedUser, and setgid to UnprivilegedGroup, thus releasing superuser
privileges.
*/
if ((grpptr = getgrnam(unprivgroup)) != NULL) {
if (!grpptr->gr_gid) {
syslog(LOG_ERR, "Group %s has incorrect privileges", unprivuser);
exit(1);
}
if (setgid(grpptr->gr_gid) == -1) {
syslog(LOG_ERR, "Error while releasing superuser privileges (changing to group '%s')", unprivgroup);
exit(1);
}
}
else {
syslog(LOG_ERR, "Error while releasing superuser privileges (group '%s' does not exist)", unprivgroup);
exit(1);
}
if ((pwdptr = getpwnam(unprivuser))) {
if (!pwdptr->pw_uid || !pwdptr->pw_gid) {
syslog(LOG_ERR, "User %s has incorrect privileges", unprivuser);
exit(1);
}
if (setuid(pwdptr->pw_uid) == -1) {
syslog(LOG_ERR, "Error while releasing superuser privileges (changing to user '%s')", unprivuser);
exit(1);
}
}
else {
syslog(LOG_ERR, "Error while releasing superuser privileges (user '%s' does not exist)", unprivuser);
exit(1);
}
if (pcap_compile(sfd, &pcap_filter, PCAP_IPV6MON_FILTER, PCAP_OPT, PCAP_NETMASK_UNKNOWN) == -1) {
syslog(LOG_ERR, "pcap_compile(): %s", pcap_geterr(sfd));
exit(1);
}
if (pcap_setfilter(sfd, &pcap_filter) == -1) {
syslog(LOG_ERR, "pcap_setfilter(): %s", pcap_geterr(sfd));
exit(1);
}
pcap_freecode(&pcap_filter);
srand(time(NULL));
hlist.mc_unrec_probe_f = probe_unrec_f;
hlist.mc_echo_probe_f = probe_echo_f;
if (get_if_addrs(&idata) == -1) {
syslog(LOG_ERR, "Error in get_if_addrs()");
exit(1);
}
if (!idata.ether_flag) {
randomize_ether_addr(&idata.ether);
idata.ether_flag = 1;
}
if (!idata.ip6_local_flag) {
ether_to_ipv6_linklocal(&idata.ether, &idata.ip6_local);
idata.ip6_local_flag = 1;
}
if (inet_pton(AF_INET6, ALL_NODES_MULTICAST_ADDR, &all_nodes_onlink) <= 0) {
syslog(LOG_ERR, "Error when converting all-nodes online multicast to binary format");
exit(1);
}
idata.mtu = ETH_DATA_LEN;
idata.ip6_global_conftime = time(NULL);
idata.ip6_global_lastcheck = time(NULL);
if ((idata.fd = pcap_fileno(sfd)) == -1) {
syslog(LOG_ERR, "Error obtaining descriptor number for pcap_t");
exit(1);
}
FD_ZERO(&sset);
FD_SET(idata.fd, &sset);
/* Catch SIGTERM so that we can do a clean shutdown */
sa.sa_handler = sigterm;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
if (sigaction(SIGTERM, &sa, NULL) < 0) {
if (verbose_f)
syslog(LOG_ERR, "Error while setting handler for SIGTERM");
exit(1);
}
/* Write the initialization notice to the log file */
if (log_start(&idata) == -1) {
syslog(LOG_ERR, "Error while writing to log file");
exit(1);
}
while (1) {
rset = sset;
wset = sset;
eset = sset;
timeout.tv_usec = 0;
timeout.tv_sec = SELECT_TIMEOUT;
if (shutdown_f) {
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
exit(1);
}
exit(0);
}
/*
Check for readability and exceptions. We only check for writeability if there is pending data
to send (the pcap descriptor will usually be writeable!).
*/
if ((sel = select(idata.fd + 1, &rset, (idata.pending_write_f ? &wset : NULL), &eset, &timeout)) == -1) {
if (errno == EINTR) {
continue;
}
else {
syslog(LOG_ERR, "Error in select() loop (%m)");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
}
curtime = time(NULL);
if (sel == 0 && (curtime - hlist.lastgcollection) > MAX_GARB_COLLECT_INT &&
(curtime - hlist.lastprocessed) > MAX_GARB_COLLECT_INT) {
if (gcollection_host_entries(&idata, &hlist) == -1) {
syslog(LOG_ERR, "Error while doing garbage collection");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
hlist.lastgcollection = curtime;
}
/*
If we didn't check for writeability in the previous call to select(), we must do it now. Otherwise, we might
block when trying to send a packet.
*/
if (!idata.pending_write_f) {
wset = sset;
timeout.tv_usec = 0;
timeout.tv_sec = 0;
if ((sel = select(idata.fd + 1, NULL, &wset, NULL, &timeout)) == -1) {
if (errno == EINTR) {
continue;
}
else {
syslog(LOG_ERR, "Error in select() loop (%m)");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
}
}
if ((idata.ip6_global_flag == VALID_MAPPING) &&
(curtime - idata.ip6_global_lastcheck) >= LOCAL_ADDRESS_TIMEOUT) {
if (check_local_addresses(&idata) == -1) {
syslog(LOG_ERR, "Error in check_local_addresses()");
exit(1);
}
}
/* If we had not configured any global address, retry now */
if ((idata.ip6_global_flag != VALID_MAPPING) && ((curtime - idata.ip6_global_conftime) >= RETRY_CONFIG)) {
if (get_if_addrs(&idata) == -1) {
syslog(LOG_ERR, "Error in get_if_addrs()");
exit(1);
}
idata.ip6_global_conftime = curtime;
}
if (FD_ISSET(idata.fd, &wset)) {
curtime = time(NULL);
if (idata.pending_write_f) {
/* There was something to send from a previous iteration, but there was no space left in the
send buffer
*/
if ((nw = pcap_inject(sfd, idata.pending_write_data, idata.pending_write_size)) < 0) {
syslog(LOG_ERR, "Error injecting packet in main loop: pcap_inject(): %s", pcap_geterr(sfd));
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
if (nw != idata.pending_write_size) {
if (verbose_f)
syslog(LOG_ERR,
"pcap_inject(): only wrote %lu bytes "
"(rather than %lu bytes)\n",
(LUI)nw, (LUI)(idata.pending_write_size));
idata.write_errors++;
if (idata.write_errors > 10) {
syslog(LOG_ERR, "Too many write errors");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
}
idata.pending_write_f = 0;
idata.write_errors = 0;
}
else if ((((idata.ip6_global.nprefix - idata.ip6_global_nconfig) &&
((curtime - idata.ip6_global_lastcheck) >= CHECK_CONFIG_INTERVAL)) ||
((curtime - idata.ip6_global_conftime) < RA_ACCEPT_WINDOW)) &&
((curtime - idata.last_rs) >= RS_SEND_INTERVAL)) {
idata.last_rs = curtime;
if (send_router_solicit(sfd, &idata) == -1) {
syslog(LOG_ERR, "Error sending Router Solicitation message");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
}
else if (hlist.mc_echo_probe_f && ((curtime - hlist.mc_echo_last) >= mcechoprobeint)) {
hlist.mc_echo_last = curtime;
if (send_multicast_probe(sfd, &idata, &hlist, PROBE_ICMP6_ECHO) != 0) {
syslog(LOG_ERR, "Error when sending multicast probe");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
}
else if (hlist.mc_unrec_probe_f && ((curtime - hlist.mc_unrec_last) >= mcunrecprobeint)) {
hlist.mc_unrec_last = curtime;
if (send_multicast_probe(sfd, &idata, &hlist, PROBE_UNREC_OPT) != 0) {
syslog(LOG_ERR, "Error when sending multicast probe");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
}
else if ((curtime - hlist.lastprocessed) > MAX_PROC_ENTRIES_INT) {
if (process_host_entries(sfd, &idata, &hlist) != 0) {
syslog(LOG_ERR, "Error while processing host entries");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
}
}
if (FD_ISSET(idata.fd, &rset)) {
error_f = 0;
do {
if ((result = pcap_next_ex(sfd, &pkthdr, &pktdata)) == -1) {
error_f = 1;
break;
}
} while (result == 0);
if (error_f) {
syslog(LOG_ERR, "Error while reading packet in main loop: pcap_next_ex(): %s", pcap_geterr(sfd));
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
pkt_ether = (struct ether_header *)pktdata;
pkt_ipv6 = (struct ip6_hdr *)((char *)pkt_ether + ETHER_HDR_LEN);
pkt_icmp6 = (struct icmp6_hdr *)((char *)pkt_ipv6 + sizeof(struct ip6_hdr));
pkt_ns = (struct nd_neighbor_solicit *)pkt_icmp6;
pkt_end = (unsigned char *)pktdata + pkthdr->caplen;
if ((pkt_end - pktdata) < (ETHER_HDR_LEN + MIN_IPV6_HLEN))
continue;
if (pkt_ipv6->ip6_nxt == IPPROTO_ICMPV6) {
if (pkt_icmp6->icmp6_type == ND_NEIGHBOR_SOLICIT) {
if ((pkt_end - (unsigned char *)pkt_ns) < sizeof(struct nd_neighbor_solicit))
continue;
/*
If the addresses that we're using are not actually configured on the local system
(i.e., they are "spoofed", we must check whether it is a Neighbor Solicitation for
one of our addresses, and respond with a Neighbor Advertisement. Otherwise, the kernel
will take care of that.
*/
if (is_ip6_in_address_list(&(idata.ip6_global), &(pkt_ns->nd_ns_target)) ||
is_eq_in6_addr(&(pkt_ns->nd_ns_target), &(idata.ip6_local))) {
if (send_neighbor_advert(&idata, sfd, pktdata) == -1) {
syslog(LOG_ERR, "Error sending Neighbor Advertisement message");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
}
else {
/*
Check whether it is a Duplicate Address Detection (DAD) packet, and if so, add the ND
Target Address as a "candidate" address
*/
/* The Source Address of the DAD packets must be the Unspecified address (::) */
if (!IN6_IS_ADDR_UNSPECIFIED(&(pkt_ipv6->ip6_src))) {
continue;
}
/* DAD packets are destined to multicast addresses (solicited-node) */
if (!IN6_IS_ADDR_MULTICAST(&(pkt_ipv6->ip6_dst))) {
continue;
}
/*
We do some sanity checks on the ND Target Address: It must not be any of the following:
a multicast address, the unspecified address, the loopback address, or any of our own
addresses
*/
if (IN6_IS_ADDR_MULTICAST(&(pkt_ns->nd_ns_target)) ||
IN6_IS_ADDR_UNSPECIFIED(&(pkt_ns->nd_ns_target)) ||
IN6_IS_ADDR_LOOPBACK(&(pkt_ns->nd_ns_target)) ||
is_ip6_in_address_list(&(idata.ip6_global), &(pkt_ns->nd_ns_target)) ||
is_eq_in6_addr(&(pkt_ns->nd_ns_target), &(idata.ip6_local))) {
continue;
}
if (hlist.ncandidates >= hlist.maxcandidates) {
syslog(LOG_INFO,
"Couldn't add candidate address: Reached limit (%u)"
" of candidate addresses",
hlist.maxcandidates);
continue;
}
if ((hptr = add_host_entry(&hlist, &(pkt_ns->nd_ns_target), &(pkt_ether->src))) == NULL) {
syslog(LOG_INFO, "Error while adding new host entry");
continue;
}
hptr->flag = INVALID_MAPPING;
hlist.ncandidates++;
}
}
else if ((pkt_icmp6->icmp6_type == ICMP6_ECHO_REPLY) || (pkt_icmp6->icmp6_type == ICMP6_PARAM_PROB)) {
if ((pkt_end - (unsigned char *)pkt_icmp6) < sizeof(struct icmp6_hdr))
continue;
/*
Do a preliminar validation check on the ICMPv6 packet (packet size, Source Address,
and Destination Address).
*/
if (valid_icmp6_response(&idata, &hlist, pkthdr, pktdata)) {
hptr = is_ip6_in_list(&hlist, &(pkt_ipv6->ip6_src));
curtime = time(NULL);
if (hptr != NULL) {
hptr->nprobes = 0;
hptr->lseen = curtime;
if (hptr->flag != VALID_MAPPING) {
hptr->flag = VALID_MAPPING;
hptr->fseen = curtime;
if (hlist.ncandidates) {
(hlist.ncandidates)--;
}
else {
syslog(LOG_ERR, "Candidates number is trashed!");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
if (log_hentry(&idata, hptr, &(hptr->fseen), ADD_ENTRY) != 0) {
syslog(LOG_ERR, "Error while logging new entry");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
}
}
else {
if ((hptr = add_host_entry(&hlist, &(pkt_ipv6->ip6_src), &(pkt_ether->src))) == NULL) {
syslog(LOG_INFO, "Error while adding new host entry");
continue;
}
if (log_hentry(&idata, hptr, &(hptr->fseen), ADD_ENTRY) != 0) {
syslog(LOG_ERR, "Error while logging new entry");
if (log_stop(&idata) == -1) {
syslog(LOG_ERR, "Error while stopping the ipv6mon daemon");
}
exit(1);
}
if ((result = create_candidate_andress(&idata, &hlist, hptr)) == -1) {
syslog(LOG_ERR, "Error while adding candidate addresses");
continue;
}
else if (result == 0) {
syslog(LOG_INFO,
"Could not add candidate address: Reached limit of "
"%u candidate addresses",
hlist.maxcandidates);
continue;
}
}
}
}
else if (pkt_icmp6->icmp6_type == ND_ROUTER_ADVERT) {
if (process_router_advert(&idata, pkthdr, pktdata) == -1) {
syslog(LOG_ERR, "Error while processing Router Advertisement"); /* XXX */
continue;
}
}
}
}
if (FD_ISSET(idata.fd, &eset)) {
syslog(LOG_ERR, "Found exception on pcap_t");
continue;
}
}
exit(0);
}
/*
* Function: usage()
*
* Prints the syntax of the na-attack tool
*/
void usage(void) { puts("usage: ipv6mon [-c CONFIG_FILE] [-q] [-v] [-h]"); }
/*
* Function: print_help()
*
* Prints help information for the na-attack tool
*/
void print_help(void) {
puts("ipv6mon version 0.2\nAn IPv6 Address Monitoring tool\n");
usage();
puts("\nOPTIONS:\n"
" --config-file, -c Configuration file pathname (defaults to '/etc/ipv6mon.conf')\n"
" --show-config, -q Shows configuration values and quits\n"
" --help, -h Print help for the scan6 tool\n"
" --verbose, -v Be verbose\n"
"\n"
" Programmed by Fernando Gont on behalf of CPNI (http://www.cpni.gov.uk)\n"
" Please send any bug reports to <fgont@si6networks.com>\n");
}
/*
* Function: in_chksum()
*
* Calculate the 16-bit ICMPv6 checksum
*/
u_int16_t in_chksum(void *ptr_ipv6, void *ptr_icmpv6, size_t len) {
struct ipv6pseudohdr pseudohdr;
struct ip6_hdr *v6packet;
size_t nleft;
unsigned int sum = 0;
u_int16_t *w;
u_int16_t answer = 0;
v6packet = ptr_ipv6;
bzero(&pseudohdr, sizeof(struct ipv6pseudohdr));
pseudohdr.srcaddr = v6packet->ip6_src;
pseudohdr.dstaddr = v6packet->ip6_dst;
pseudohdr.len = htons(len);
pseudohdr.nh = IPPROTO_ICMPV6;
nleft = 40;
w = (u_int16_t *)&pseudohdr;
while (nleft > 1) {
sum += *w++;
nleft -= 2;
}
nleft = len;
w = (u_int16_t *)ptr_icmpv6;
while (nleft > 1) {
sum += *w++;
nleft -= 2;
}
if (nleft == 1) {
*(unsigned char *)(&answer) = *(unsigned char *)w;
sum += answer;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer = ~sum;
return (answer);
}
/*
* Function: ether_pton()
*
* Convert a string (printable Ethernet Address) into binary format
*/
int ether_pton(const char *ascii, struct ether_addr *etheraddr, unsigned int s) {
unsigned int i, a[6];
if (s < ETHER_ADDR_LEN)
return 0;
if (ascii) {
if (sscanf(ascii, "%x:%x:%x:%x:%x:%x", &a[0], &a[1], &a[2], &a[3], &a[4], &a[5]) == 6) {
for (i = 0; i < 6; i++)
etheraddr->a[i] = a[i];
return 1;
}
}
return 0;
}
/*
* Function: ether_ntop()
*
* Convert binary Ethernet Address into printable foramt (an ASCII string)
*/
int ether_ntop(const struct ether_addr *ether, char *ascii, size_t s) {
unsigned int r;
if (s < ETHER_ADDR_PLEN)
return 0;
r = snprintf(ascii, s, "%02x:%02x:%02x:%02x:%02x:%02x", ether->a[0], ether->a[1], ether->a[2], ether->a[3],
ether->a[4], ether->a[5]);
if (r != 17)
return 0;
return 1;
}
/*
* Function match_ipv6()
*
* Finds if an IPv6 address matches a prefix in a list of prefixes.
*/
unsigned int match_ipv6(struct in6_addr *prefixlist, u_int8_t *prefixlen, unsigned int nprefix,
struct in6_addr *ipv6addr) {
unsigned int i;
struct in6_addr dummyipv6;
for (i = 0; i < nprefix; i++) {
dummyipv6 = *ipv6addr;
sanitize_ipv6_prefix(&dummyipv6, prefixlen[i]);