Add --vpn (-X) flag to support sending IP pkts
When a user specifies a `-i tun0` flag for a VPN interface, this interface expects raw IP packets, not ethernet frames. The --vpn option allows you to send only IP packets to the specified interface, and also performs some hacks on the receive end to ensure we can process the results. TODO: malloc a fake ethernet header for probe_modules.process_packet (or better yet, make process_packet always take an IP packet, they all seem to be implicitly doing that anyway).
This commit is contained in:
Eric
parent
8f5e4beb01
commit
2972bbefdc
20
src/recv.c
20
src/recv.c
@ -74,12 +74,12 @@ void packet_cb(u_char __attribute__((__unused__)) *user,
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// length of entire packet captured by libpcap
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uint32_t buflen = (uint32_t) p->caplen;
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if ((sizeof(struct iphdr) + sizeof(struct ethhdr)) > buflen) {
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if ((sizeof(struct iphdr) + (zconf.send_ip_pkts ? 0 : sizeof(struct ethhdr))) > buflen) {
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// buffer not large enough to contain ethernet
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// and ip headers. further action would overrun buf
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return;
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}
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struct iphdr *ip_hdr = (struct iphdr *)&bytes[sizeof(struct ethhdr)];
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struct iphdr *ip_hdr = (struct iphdr *)&bytes[(zconf.send_ip_pkts ? 0 : sizeof(struct ethhdr))];
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uint32_t src_ip = ip_hdr->saddr;
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@ -88,7 +88,7 @@ void packet_cb(u_char __attribute__((__unused__)) *user,
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// and we must calculate off potential payload message instead
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validate_gen(ip_hdr->daddr, ip_hdr->saddr, (uint8_t *)validation);
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if (!zconf.probe_module->validate_packet(ip_hdr, buflen - sizeof(struct ethhdr),
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if (!zconf.probe_module->validate_packet(ip_hdr, buflen - (zconf.send_ip_pkts ? 0 : sizeof(struct ethhdr)),
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&src_ip, validation)) {
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return;
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}
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@ -97,7 +97,18 @@ void packet_cb(u_char __attribute__((__unused__)) *user,
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fieldset_t *fs = fs_new_fieldset();
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fs_add_ip_fields(fs, ip_hdr);
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zconf.probe_module->process_packet(bytes, buflen, fs);
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// HACK !!! FIXME !!! TODO !!! BAD BAD BAD
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// probe modules for whatever reason expect the full ethernet frame
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// in process_packet. For VPN, we only get back an IP frame
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// so we COULD malloc a fake ethernet frame and copy over this payload
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// but waaaaaaahhhh performanceeee.
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// so instead, we will ASSUME (!) that the probe module will only care about
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// the IP header, and do ip_hdr = &packet[sizeof(struct ethhdr)] the first thing
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// in their function (tcp, icmp and udp probe modules all do).
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//
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// !!!IF YOUR PROBE MODULE USES THE ETH PACKET, AND YOU USE THE --vpn OPTION, YOU _WILL_ BE OWNED!!!!
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//
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zconf.probe_module->process_packet(bytes - (zconf.send_ip_pkts * sizeof(struct ethhdr)), buflen + (zconf.send_ip_pkts * sizeof(struct ethhdr)), fs);
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fs_add_system_fields(fs, is_repeat, zsend.complete);
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int success_index = zconf.fsconf.success_index;
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assert(success_index < fs->len);
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@ -115,7 +126,6 @@ void packet_cb(u_char __attribute__((__unused__)) *user,
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zrecv.cooldown_unique++;
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}
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}
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} else {
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zrecv.failure_total++;
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}
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@ -288,7 +288,7 @@ int send_run(int sock)
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zconf.probe_module->print_packet(stdout, buf);
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} else {
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int l = zconf.probe_module->packet_length;
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int rc = sendto(sock, buf,
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int rc = sendto(sock, buf + zconf.send_ip_pkts*sizeof(struct ethhdr),
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l, 0,
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(struct sockaddr *)&sockaddr,
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sizeof(struct sockaddr_ll));
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@ -36,6 +36,7 @@ struct state_conf zconf = {
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.probe_args = NULL,
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.gw_mac = {0},
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.gw_mac_set = 0,
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.send_ip_pkts = 0,
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.source_ip_first = NULL,
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.source_ip_last = NULL,
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.raw_output_fields = NULL,
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@ -71,6 +71,7 @@ struct state_conf {
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char *output_args;
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macaddr_t gw_mac[IFHWADDRLEN];
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int gw_mac_set;
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int send_ip_pkts;
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char *source_ip_first;
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char *source_ip_last;
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char *output_filename;
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@ -397,6 +397,11 @@ int main(int argc, char *argv[])
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exit(EXIT_FAILURE);
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}
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}
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if (args.vpn_given) {
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zconf.send_ip_pkts = 1;
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zconf.gw_mac_set = 1;
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memset(zconf.gw_mac, 0, IFHWADDRLEN);
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}
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if (cmdline_parser_required(&args, CMDLINE_PARSER_PACKAGE) != 0) {
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exit(EXIT_FAILURE);
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}
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48
src/zopt.c
48
src/zopt.c
@ -54,6 +54,7 @@ const char *gengetopt_args_info_help[] = {
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" -S, --source-ip=ip|range Source address(es) for scan packets",
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" -G, --gateway-mac=addr Specify gateway MAC address",
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" -i, --interface=name Specify network interface to use",
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" -X, --vpn Sends IP packets instead of Ethernet (for VPNs)",
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"\nAdvanced options:",
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" -M, --probe-module=name Select probe module (default=`tcp_synscan')",
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" -O, --output-module=name Select output module (default=`csv')",
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@ -137,6 +138,7 @@ void clear_given (struct gengetopt_args_info *args_info)
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args_info->source_ip_given = 0 ;
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args_info->gateway_mac_given = 0 ;
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args_info->interface_given = 0 ;
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args_info->vpn_given = 0 ;
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args_info->probe_module_given = 0 ;
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args_info->output_module_given = 0 ;
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args_info->probe_args_given = 0 ;
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@ -226,19 +228,20 @@ void init_args_info(struct gengetopt_args_info *args_info)
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args_info->source_ip_help = gengetopt_args_info_help[19] ;
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args_info->gateway_mac_help = gengetopt_args_info_help[20] ;
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args_info->interface_help = gengetopt_args_info_help[21] ;
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args_info->probe_module_help = gengetopt_args_info_help[23] ;
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args_info->output_module_help = gengetopt_args_info_help[24] ;
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args_info->probe_args_help = gengetopt_args_info_help[25] ;
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args_info->output_args_help = gengetopt_args_info_help[26] ;
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args_info->list_output_modules_help = gengetopt_args_info_help[27] ;
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args_info->list_probe_modules_help = gengetopt_args_info_help[28] ;
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args_info->list_output_fields_help = gengetopt_args_info_help[29] ;
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args_info->config_help = gengetopt_args_info_help[31] ;
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args_info->quiet_help = gengetopt_args_info_help[32] ;
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args_info->summary_help = gengetopt_args_info_help[33] ;
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args_info->verbosity_help = gengetopt_args_info_help[34] ;
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args_info->help_help = gengetopt_args_info_help[35] ;
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args_info->version_help = gengetopt_args_info_help[36] ;
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args_info->vpn_help = gengetopt_args_info_help[22] ;
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args_info->probe_module_help = gengetopt_args_info_help[24] ;
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args_info->output_module_help = gengetopt_args_info_help[25] ;
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args_info->probe_args_help = gengetopt_args_info_help[26] ;
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args_info->output_args_help = gengetopt_args_info_help[27] ;
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args_info->list_output_modules_help = gengetopt_args_info_help[28] ;
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args_info->list_probe_modules_help = gengetopt_args_info_help[29] ;
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args_info->list_output_fields_help = gengetopt_args_info_help[30] ;
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args_info->config_help = gengetopt_args_info_help[32] ;
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args_info->quiet_help = gengetopt_args_info_help[33] ;
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args_info->summary_help = gengetopt_args_info_help[34] ;
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args_info->verbosity_help = gengetopt_args_info_help[35] ;
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args_info->help_help = gengetopt_args_info_help[36] ;
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args_info->version_help = gengetopt_args_info_help[37] ;
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}
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@ -426,6 +429,8 @@ cmdline_parser_dump(FILE *outfile, struct gengetopt_args_info *args_info)
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write_into_file(outfile, "gateway-mac", args_info->gateway_mac_orig, 0);
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if (args_info->interface_given)
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write_into_file(outfile, "interface", args_info->interface_orig, 0);
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if (args_info->vpn_given)
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write_into_file(outfile, "vpn", 0, 0 );
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if (args_info->probe_module_given)
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write_into_file(outfile, "probe-module", args_info->probe_module_orig, 0);
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if (args_info->output_module_given)
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@ -721,6 +726,7 @@ cmdline_parser_internal (
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{ "source-ip", 1, NULL, 'S' },
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{ "gateway-mac", 1, NULL, 'G' },
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{ "interface", 1, NULL, 'i' },
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{ "vpn", 0, NULL, 'X' },
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{ "probe-module", 1, NULL, 'M' },
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{ "output-module", 1, NULL, 'O' },
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{ "probe-args", 1, NULL, 0 },
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@ -737,7 +743,7 @@ cmdline_parser_internal (
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{ 0, 0, 0, 0 }
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};
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c = getopt_long (argc, argv, "p:o:b:w:f:n:N:t:r:B:c:e:T:P:ds:S:G:i:M:O:C:qgv:hV", long_options, &option_index);
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c = getopt_long (argc, argv, "p:o:b:w:f:n:N:t:r:B:c:e:T:P:ds:S:G:i:XM:O:C:qgv:hV", long_options, &option_index);
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if (c == -1) break; /* Exit from `while (1)' loop. */
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@ -970,6 +976,18 @@ cmdline_parser_internal (
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additional_error))
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goto failure;
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break;
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case 'X': /* Sends IP packets instead of Ethernet (for VPNs). */
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if (update_arg( 0 ,
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0 , &(args_info->vpn_given),
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&(local_args_info.vpn_given), optarg, 0, 0, ARG_NO,
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check_ambiguity, override, 0, 0,
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"vpn", 'X',
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additional_error))
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goto failure;
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break;
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case 'M': /* Select probe module. */
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@ -988,7 +1006,7 @@ cmdline_parser_internal (
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if (update_arg( (void *)&(args_info->output_module_arg),
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&(args_info->output_module_orig), &(args_info->output_module_given),
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&(local_args_info.output_module_given), optarg, 0, "simple_file", ARG_STRING,
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&(local_args_info.output_module_given), optarg, 0, "csv", ARG_STRING,
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check_ambiguity, override, 0, 0,
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"output-module", 'O',
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additional_error))
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@ -75,6 +75,8 @@ option "gateway-mac" G "Specify gateway MAC address"
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option "interface" i "Specify network interface to use"
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typestr="name"
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optional string
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option "vpn" X "Sends IP packets instead of Ethernet (for VPNs)"
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optional
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section "Advanced options"
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@ -84,7 +86,7 @@ option "probe-module" M "Select probe module"
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optional string
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option "output-module" O "Select output module"
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typestr="name"
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default="simple_file"
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default="csv"
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optional string
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option "probe-args" - "Arguments to pass to probe module"
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typestr="args"
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@ -92,10 +92,11 @@ struct gengetopt_args_info
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char * interface_arg; /**< @brief Specify network interface to use. */
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char * interface_orig; /**< @brief Specify network interface to use original value given at command line. */
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const char *interface_help; /**< @brief Specify network interface to use help description. */
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const char *vpn_help; /**< @brief Sends IP packets instead of Ethernet (for VPNs) help description. */
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char * probe_module_arg; /**< @brief Select probe module (default='tcp_synscan'). */
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char * probe_module_orig; /**< @brief Select probe module original value given at command line. */
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const char *probe_module_help; /**< @brief Select probe module help description. */
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char * output_module_arg; /**< @brief Select output module (default='simple_file'). */
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char * output_module_arg; /**< @brief Select output module (default='csv'). */
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char * output_module_orig; /**< @brief Select output module original value given at command line. */
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const char *output_module_help; /**< @brief Select output module help description. */
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char * probe_args_arg; /**< @brief Arguments to pass to probe module. */
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@ -137,6 +138,7 @@ struct gengetopt_args_info
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unsigned int source_ip_given ; /**< @brief Whether source-ip was given. */
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unsigned int gateway_mac_given ; /**< @brief Whether gateway-mac was given. */
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unsigned int interface_given ; /**< @brief Whether interface was given. */
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unsigned int vpn_given ; /**< @brief Whether vpn was given. */
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unsigned int probe_module_given ; /**< @brief Whether probe-module was given. */
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unsigned int output_module_given ; /**< @brief Whether output-module was given. */
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unsigned int probe_args_given ; /**< @brief Whether probe-args was given. */
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