edge.c

/**
 * (C) 2007-20 - ntop.org and contributors
 *
 * 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 see <http://www.gnu.org/licenses/>
 *
 */

#include "n2n.h"

/* *************************************************** */

/** maximum length of command line arguments */
#define MAX_CMDLINE_BUFFER_LENGTH        4096

/** maximum length of a line in the configuration file */
#define MAX_CONFFILE_LINE_LENGTH         1024

/* ***************************************************** */

#ifdef HAVE_LIBCAP

#include <sys/capability.h>
#include <sys/prctl.h>
#include "network_traffic_filter.h"

static cap_value_t cap_values[] = {
    //CAP_NET_RAW,            /* Use RAW and PACKET sockets */
    CAP_NET_ADMIN         /* Needed to performs routes cleanup at exit */
};

int num_cap = sizeof(cap_values)/sizeof(cap_value_t);
#endif

/* ***************************************************** */

/** Find the address and IP mode for the tuntap device.
 *
 *    s is of the form:
 *
 * ["static"|"dhcp",":"] (<host>|<ip>) [/<cidr subnet mask>]
 *
 * for example        static:192.168.8.5/24
 *
 * Fill the parts of the string into the fileds, ip_mode only if
 * present. All strings are NULL terminated.
 *
 *    return 0 on success and -1 on error
 */
static int scan_address (char * ip_addr, size_t addr_size,
                         char * netmask, size_t netmask_size,
                         char * ip_mode, size_t mode_size,
                         char * s) {

    int retval = -1;
    char * start;
    char * end;
    int bitlen = N2N_EDGE_DEFAULT_CIDR_NM;

    if((NULL == s) || (NULL == ip_addr) || (NULL == netmask)) {
        return -1;
    }

    memset(ip_addr, 0, addr_size);
    memset(netmask, 0, netmask_size);

    start = s;
    end = strpbrk(s, ":");

    if(end) {
        // colon is present
        if(ip_mode) {
            memset(ip_mode, 0, mode_size);
            strncpy(ip_mode, start, (size_t)MIN(end - start, mode_size - 1));
        }
        start = end + 1;
    } else {
        // colon is not present
    }
    // start now points to first address character
    retval = 0; // we have got an address

    end = strpbrk(start, "/");

    if(!end)
        // no slash present -- default end
        end = s + strlen(s);

    strncpy(ip_addr, start, (size_t)MIN(end - start, addr_size - 1)); // ensure NULL term

    if(end) {
        // slash is present

        // now, handle the sub-network address
        sscanf(end + 1, "%u", &bitlen);
        bitlen = htobe32(bitlen2mask(bitlen));
        inet_ntop(AF_INET, &bitlen, netmask, netmask_size);
    }

    return retval;
}

/* *************************************************** */

static void help () {
    print_n2n_version();

    printf("edge <config file> (see edge.conf)\n"
                 "or\n"
                 );
    printf("edge "
#if defined(N2N_CAN_NAME_IFACE)
                 "-d <tap device> "
#endif /* #if defined(N2N_CAN_NAME_IFACE) */
                 "-a [static:|dhcp:]<tap IP address>[/nn] "
                 "-c <community> "
                 "[-k <encrypt key>]\n"
                 "        "
#ifndef WIN32
                 "[-u <uid> -g <gid>]"
#endif /* #ifndef WIN32 */

#ifndef WIN32
                 "[-f]"
#endif /* #ifndef WIN32 */
#ifdef __linux__
                 "[-T <tos>]"
#endif
                 "[-n cidr:gateway] "
                 "[-m <MAC address>] "
                 "-l <supernode host:port>\n"
                 "        "
                 "[-p <local port>] [-M <mtu>] "
#ifndef __APPLE__
                 "[-D] "
#endif
                 "[-r] [-E] [-v] [-i <reg_interval>] [-L <reg_ttl>] [-t <mgmt port>] [-A[<cipher>]] [-H] [-z[<compression algo>]] "
                 "[-R <rule_str>] "
                 "[-h]\n\n");

#if defined(N2N_CAN_NAME_IFACE)
    printf("-d <tap device>          | tap device name\n");
#endif

    printf("-a [mode:]<address>[/nn] | Interface address and optional subnet (cidr, default /24). For DHCP use '-r -a dhcp:0.0.0.0'\n");
    printf("-c <community>           | n2n community name the edge belongs to.\n");
    printf("-k <encrypt key>         | Encryption key (ASCII) - also N2N_KEY=<encrypt key>.\n");
    printf("-l <supernode host:port> | Supernode IP:port\n");
    printf("-i <reg_interval>        | Registration interval, for NAT hole punching (default 20 seconds)\n");
    printf("-I <device description>  | Annotate the edge's description (hint), identified in the manage port\n");
    printf("-L <reg_ttl>             | TTL for registration packet when UDP NAT hole punching through supernode (default 0 for not set )\n");
    printf("-p <local port>          | Fixed local UDP port.\n");
#ifndef WIN32
    printf("-u <UID>                 | User ID (numeric) to use when privileges are dropped.\n");
    printf("-g <GID>                 | Group ID (numeric) to use when privileges are dropped.\n");
#endif /* ifndef WIN32 */
#ifndef WIN32
    printf("-f                       | Do not fork and run as a daemon; rather run in foreground.\n");
#endif /* #ifndef WIN32 */
    printf("-m <MAC address>         | Fix MAC address for the TAP interface (otherwise it may be random)\n"
           "                         | eg. -m 01:02:03:04:05:06\n");
    printf("-M <mtu>                 | Specify n2n MTU of edge interface (default %d).\n", DEFAULT_MTU);
#ifndef __APPLE__
    printf("-D                       | Enable PMTU discovery. PMTU discovery can reduce fragmentation but\n"
           "                         | causes connections stall when not properly supported.\n");
#endif
    printf("-r                       | Enable packet forwarding through n2n community.\n");
    printf("-A1                      | Disable payload encryption. Do not use with key (defaulting to AES then).\n");
    printf("-A2 ... -A5 or -A        | Choose a cipher for payload encryption, requires a key: -A2 = Twofish,\n");
    printf("                         | -A3 or -A (deprecated) = AES (default), "
           "-A4 = ChaCha20, "
           "-A5 = Speck-CTR.\n");
    printf("-H                       | Enable full header encryption. Requires supernode with fixed community.\n");
    printf("-z1 ... -z2 or -z        | Enable compression for outgoing data packets: -z1 or -z = lzo1x"
#ifdef N2N_HAVE_ZSTD
           ", -z2 = zstd"
#endif
           " (default=disabled).\n");
    printf("-E                       | Accept multicast MAC addresses (default=drop).\n");
    printf("-S                       | Do not connect P2P. Always use the supernode.\n");
#ifdef __linux__
    printf("-T <tos>                 | TOS for packets (e.g. 0x48 for SSH like priority)\n");
#endif
    printf("-n <cidr:gateway>        | Route an IPv4 network via the gw. Use 0.0.0.0/0 for the default gw. Can be set multiple times.\n");
    printf("-v                       | Make more verbose. Repeat as required.\n");
    printf("-R <rule_str>            | Drop or accept packets by rules. Can be set multiple times. \n");
    printf("                         | Rule format: src_ip/len:[b_port,e_port],dst_ip/len:[s_port,e_port],TCP+/-,UDP+/-,ICMP+/- \n");
    printf("-t <port>                | Management UDP Port (for multiple edges on a machine).\n");

    printf("\nEnvironment variables:\n");
    printf("    N2N_KEY              | Encryption key (ASCII). Not with -k.\n");

#ifdef WIN32
    printf("\nAvailable TAP adapters:\n");
    win_print_available_adapters();
#endif

    exit(0);
}

/* *************************************************** */

static void setPayloadCompression (n2n_edge_conf_t *conf, int compression) {

    /* even though 'compression' and 'conf->compression' share the same encoding scheme,
     * a switch-statement under conditional compilation is used to sort out the
     * unsupported optarguments */
    switch (compression) {
        case 1: {
            conf->compression = N2N_COMPRESSION_ID_LZO;
            break;
        }
#ifdef N2N_HAVE_ZSTD
        case 2: {
            conf->compression = N2N_COMPRESSION_ID_ZSTD;
            break;
        }
#endif
        default: {
            conf->compression = N2N_COMPRESSION_ID_NONE;
            // internal comrpession scheme numbering differs from cli counting by one, hence plus one
            // (internal: 0 == invalid, 1 == none, 2 == lzo, 3 == zstd)
            traceEvent(TRACE_NORMAL, "the %s compression given by -z_ option is not supported in this version.", compression_str(compression + 1));
            exit(1); // to make the user aware
        }
    }
}

/* *************************************************** */

static void setPayloadEncryption (n2n_edge_conf_t *conf, int cipher) {

    /* even though 'cipher' and 'conf->transop_id' share the same encoding scheme,
     * a switch-statement under conditional compilation is used to sort out the
     * unsupported ciphers */
    switch (cipher) {
        case 1: {
            conf->transop_id = N2N_TRANSFORM_ID_NULL;
            break;
        }

        case 2: {
            conf->transop_id = N2N_TRANSFORM_ID_TWOFISH;
            break;
        }

        case 3: {
            conf->transop_id = N2N_TRANSFORM_ID_AES;
            break;
        }

        case 4: {
            conf->transop_id = N2N_TRANSFORM_ID_CHACHA20;
            break;
        }

        case 5: {
            conf->transop_id = N2N_TRANSFORM_ID_SPECK;
            break;
        }

        default: {
            conf->transop_id = N2N_TRANSFORM_ID_INVAL;
            traceEvent(TRACE_NORMAL, "the %s cipher given by -A_ option is not supported in this version.", transop_str(cipher));
            exit(1);
        }
    }
}

/* *************************************************** */

static int setOption (int optkey, char *optargument, n2n_tuntap_priv_config_t *ec, n2n_edge_conf_t *conf) {

    /* traceEvent(TRACE_NORMAL, "Option %c = %s", optkey, optargument ? optargument : ""); */

    switch(optkey) {
        case 'a': /* IP address and mode of TUNTAP interface */ {
            scan_address(ec->ip_addr, N2N_NETMASK_STR_SIZE,
                                     ec->netmask, N2N_NETMASK_STR_SIZE,
                                     ec->ip_mode, N2N_IF_MODE_SIZE,
                                     optargument);
            break;
        }

        case 'c': /* community as a string */ {
            memset(conf->community_name, 0, N2N_COMMUNITY_SIZE);
            strncpy((char *)conf->community_name, optargument, N2N_COMMUNITY_SIZE);
            conf->community_name[N2N_COMMUNITY_SIZE - 1] = '\0';
            break;
        }

        case 'E': /* multicast ethernet addresses accepted. */ {
            conf->drop_multicast = 0;
            traceEvent(TRACE_DEBUG, "Enabling ethernet multicast traffic");
            break;
        }

#ifndef WIN32
        case 'u': /* unprivileged uid */ {
            ec->userid = atoi(optargument);
            break;
        }

        case 'g': /* unprivileged uid */ {
            ec->groupid = atoi(optargument);
            break;
        }
#endif

#ifndef WIN32
        case 'f' : /* do not fork as daemon */ {
            ec->daemon = 0;
            break;
        }
#endif /* #ifndef WIN32 */

        case 'm' : /* TUNTAP MAC address */ {
            strncpy(ec->device_mac, optargument, N2N_MACNAMSIZ);
            ec->device_mac[N2N_MACNAMSIZ - 1] = '\0';
            break;
        }

        case 'M' : /* TUNTAP MTU */ {
            ec->mtu = atoi(optargument);
            break;
        }

#ifndef __APPLE__
        case 'D' : /* enable PMTU discovery */ {
            conf->disable_pmtu_discovery = 0;
            break;
        }
#endif

        case 'k': /* encrypt key */ {
            if(conf->encrypt_key) free(conf->encrypt_key);
            conf->encrypt_key = strdup(optargument);
            traceEvent(TRACE_DEBUG, "encrypt_key = '%s'\n", conf->encrypt_key);
            break;
        }

        case 'r': /* enable packet routing across n2n endpoints */ {
            conf->allow_routing = 1;
            break;
        }

        case 'A': {
            int cipher;

            if(optargument) {
                cipher = atoi(optargument);
            } else {
                traceEvent(TRACE_NORMAL, "the use of the solitary -A switch is deprecated and might not be supported in future versions. "
                           "please use -A3 instead to choose a the AES cipher for payload encryption.");

                cipher = N2N_TRANSFORM_ID_AES; // default, if '-A' only
            }

            setPayloadEncryption(conf, cipher);
            break;
        }

        case 'H': /* indicate header encryption */ {
            /* we cannot be sure if this gets parsed before the community name is set.
             * so, only an indicator is set, action is taken later*/
            conf->header_encryption = HEADER_ENCRYPTION_ENABLED;
            break;
        }

        case 'z': {
            int compression;

            if(optargument) {
                compression = atoi(optargument);
            } else
                compression = 1; // default, if '-z' only, equals -z1

            setPayloadCompression(conf, compression);
            break;
        }

        case 'l': /* supernode-list */
            if(optargument) {
                if(edge_conf_add_supernode(conf, optargument) != 0) {
                    traceEvent(TRACE_WARNING, "Too many supernodes!");
                    exit(1);
                }
                break;
            }

        case 'i': /* supernode registration interval */
            conf->register_interval = atoi(optargument);
            break;

        case 'L': /* supernode registration interval */
            conf->register_ttl = atoi(optarg);
            break;

#if defined(N2N_CAN_NAME_IFACE)
        case 'd': /* TUNTAP name */ {
            strncpy(ec->tuntap_dev_name, optargument, N2N_IFNAMSIZ);
            ec->tuntap_dev_name[N2N_IFNAMSIZ - 1] = '\0';
            break;
        }
#endif

        case 'I': /* Device Description (hint) */ {
            memset(conf->dev_desc, 0, N2N_DESC_SIZE);
            /* reserve possible last char as null terminator. */
            strncpy((char *)conf->dev_desc, optargument, N2N_DESC_SIZE-1);
            break;
        }

        case 'p': {
            conf->local_port = atoi(optargument);

            if(conf->local_port == 0) {
                traceEvent(TRACE_WARNING, "Bad local port format");
                break;
            }

            break;
        }

        case 't': {
            conf->mgmt_port = atoi(optargument);
            break;
        }

#ifdef __linux__
        case 'T': {
            if((optargument[0] == '0') && (optargument[1] == 'x'))
                conf->tos = strtol(&optargument[2], NULL, 16);
            else
                conf->tos = atoi(optargument);

            break;
        }
#endif

        case 'n': {
            char cidr_net[64], gateway[64];
            n2n_route_t route;

            if(sscanf(optargument, "%63[^/]/%hhd:%63s", cidr_net, &route.net_bitlen, gateway) != 3) {
                traceEvent(TRACE_WARNING, "Bad cidr/gateway format '%d'. See -h.", optargument);
                break;
            }

            route.net_addr = inet_addr(cidr_net);
            route.gateway = inet_addr(gateway);

            if((route.net_bitlen < 0) || (route.net_bitlen > 32)) {
                traceEvent(TRACE_WARNING, "Bad prefix '%d' in '%s'", route.net_bitlen, optargument);
                break;
            }

            if(route.net_addr == INADDR_NONE) {
                traceEvent(TRACE_WARNING, "Bad network '%s' in '%s'", cidr_net, optargument);
                break;
            }

            if(route.gateway == INADDR_NONE) {
                traceEvent(TRACE_WARNING, "Bad gateway '%s' in '%s'", gateway, optargument);
                break;
            }

            traceEvent(TRACE_DEBUG, "Adding %s/%d via %s", cidr_net, route.net_bitlen, gateway);

            conf->routes = realloc(conf->routes, sizeof(struct n2n_route) * (conf->num_routes + 1));
            conf->routes[conf->num_routes] = route;
            conf->num_routes++;

            break;
        }

        case 'S': {
            conf->allow_p2p = 0;
            break;
        }

        case 'h': /* help */ {
            help();
            break;
        }

        case 'v': /* verbose */
            setTraceLevel(getTraceLevel() + 1);
            break;

        case 'R': /* network traffic filter */ {
            filter_rule_t *new_rule = malloc(sizeof(filter_rule_t));
            memset(new_rule, 0, sizeof(filter_rule_t));

            if(process_traffic_filter_rule_str(optargument, new_rule)) {
                HASH_ADD(hh, conf->network_traffic_filter_rules, key, sizeof(filter_rule_key_t), new_rule);
            } else {
                free(new_rule);
                traceEvent(TRACE_WARNING, "Invalid filter rule: %s", optargument);
                return(-1);
            }
            break;
        }

        default: {
            traceEvent(TRACE_WARNING, "Unknown option -%c: Ignored", (char)optkey);
            return(-1);
        }
    }

    return(0);
}

/* *********************************************** */

static const struct option long_options[] =
    {
        { "community",             required_argument, NULL, 'c' },
        { "supernode-list",    required_argument, NULL, 'l' },
        { "tap-device",            required_argument, NULL, 'd' },
        { "euid",                        required_argument, NULL, 'u' },
        { "egid",                        required_argument, NULL, 'g' },
        { "help"     ,                 no_argument,             NULL, 'h' },
        { "verbose",                 no_argument,             NULL, 'v' },
        { NULL,                            0,                                 NULL,    0    }
    };

/* *************************************************** */

/* read command line options */
static int loadFromCLI (int argc, char *argv[], n2n_edge_conf_t *conf, n2n_tuntap_priv_config_t *ec) {

    u_char c;

    while ((c = getopt_long(argc, argv,
                            "k:a:bc:Eu:g:m:M:s:d:l:p:fvhrt:i:I:SDL:z::A::Hn:R:"
#ifdef __linux__
                            "T:"
#endif
                            ,
                            long_options, NULL)) != '?') {
        if(c == 255) break;
        setOption(c, optarg, ec, conf);
    }

    return 0;
}

/* *************************************************** */

static char *trim (char *s) {

    char *end;

    while(isspace(s[0]) || (s[0] == '"') || (s[0] == '\'')) s++;
    if(s[0] == 0) return s;

    end = &s[strlen(s) - 1];
    while(end > s
                && (isspace(end[0])|| (end[0] == '"') || (end[0] == '\'')))
        end--;
    end[1] = 0;

    return s;
}

/* *************************************************** */

/* parse the configuration file */
static int loadFromFile (const char *path, n2n_edge_conf_t *conf, n2n_tuntap_priv_config_t *ec) {

    char buffer[4096], *line, *key, *value;
    u_int line_len, opt_name_len;
    FILE *fd;
    const struct option *opt;

    fd = fopen(path, "r");

    if(fd == NULL) {
        traceEvent(TRACE_WARNING, "Config file %s not found", path);
        return -1;
    }

    while((line = fgets(buffer, sizeof(buffer), fd)) != NULL) {
        line = trim(line);
        value = NULL;

        if((line_len = strlen(line)) < 2 || line[0] == '#')
            continue;

        if(!strncmp(line, "--", 2)) { /* long opt */
            key = &line[2], line_len -= 2;

            opt = long_options;
            while(opt->name != NULL) {
                opt_name_len = strlen(opt->name);

                if(!strncmp(key, opt->name, opt_name_len)
                   && (line_len <= opt_name_len
                       || key[opt_name_len] == '\0'
                       || key[opt_name_len] == ' '
                       || key[opt_name_len] == '=')) {
                    if(line_len > opt_name_len) key[opt_name_len] = '\0';
                    if(line_len > opt_name_len + 1) value = trim(&key[opt_name_len + 1]);

                    // traceEvent(TRACE_NORMAL, "long key: %s value: %s", key, value);
                    setOption(opt->val, value, ec, conf);
                    break;
                }

                opt++;
            }
        } else if(line[0] == '-') { /* short opt */
            char *equal;

            key = &line[1], line_len--;

            equal = strchr(line, '=');

            if(equal) {
                equal[0] = '\0';
                value = &equal[1];

                if((value[0] == '\0') && (key[1] != '\0'))
                    value = &key[1];
            } else {
                value = NULL;

                /* Adding an exception for -A_ -z_ which can come
                   without '=' and even without any further data */

                if(key[0] == 'z') {
                    if(key[1]) value = &key[1];
                    key = "z";
                } else if(key[0] == 'A') {
                    if(key[1]) value = &key[1];
                    key = "A";
                }
            }
            // traceEvent(TRACE_NORMAL, "key: %c value: %s", key[0], value);
            setOption(key[0], value, ec, conf);
        } else {
            traceEvent(TRACE_WARNING, "Skipping unrecognized line: %s", line);
            continue;
        }
    }

    fclose(fd);

    return 0;
}

/* ************************************** */

static void daemonize () {
#ifndef WIN32
    int childpid;

    traceEvent(TRACE_NORMAL, "Parent process is exiting (this is normal)");

    signal(SIGPIPE, SIG_IGN);
    signal(SIGHUP,  SIG_IGN);
    signal(SIGCHLD, SIG_IGN);
    signal(SIGQUIT, SIG_IGN);

    if((childpid = fork()) < 0)
        traceEvent(TRACE_ERROR, "Occurred while daemonizing (errno=%d)",
                   errno);
    else {
        if(!childpid) { /* child */
            int rc;

            //traceEvent(TRACE_NORMAL, "Bye bye: I'm becoming a daemon...");
            rc = chdir("/");
            if(rc != 0)
                traceEvent(TRACE_ERROR, "Error while moving to / directory");

            setsid();    /* detach from the terminal */

            fclose(stdin);
            fclose(stdout);
            /* fclose(stderr); */

            /*
             * clear any inherited file mode creation mask
             */
            //umask(0);

            /*
             * Use line buffered stdout
             */
            /* setlinebuf (stdout); */
            setvbuf(stdout, (char *)NULL, _IOLBF, 0);
        } else /* father */
            exit(0);
    }
#endif
}

/* *************************************************** */

static int keep_on_running;

#if defined(__linux__) || defined(WIN32)
#ifdef WIN32
BOOL WINAPI term_handler(DWORD sig)
#else
    static void term_handler(int sig)
#endif
{
    static int called = 0;

    if(called) {
        traceEvent(TRACE_NORMAL, "Ok I am leaving now");
        _exit(0);
    } else {
        traceEvent(TRACE_NORMAL, "Shutting down...");
        called = 1;
    }

    keep_on_running = 0;
#ifdef WIN32
    return(TRUE);
#endif
}
#endif /* defined(__linux__) || defined(WIN32) */

/* *************************************************** */

/** Entry point to program from kernel. */
int main (int argc, char* argv[]) {

    int rc;
    tuntap_dev tuntap;        /* a tuntap device */
    n2n_edge_t *eee;            /* single instance for this program */
    n2n_edge_conf_t conf; /* generic N2N edge config */
    n2n_tuntap_priv_config_t ec; /* config used for standalone program execution */
#ifndef WIN32
    struct passwd *pw = NULL;
#endif
#ifdef HAVE_LIBCAP
    cap_t caps;
#endif
#ifdef WIN32
    initWin32();
#endif

    /* Defaults */
    edge_init_conf_defaults(&conf);
    memset(&ec, 0, sizeof(ec));
    ec.mtu = DEFAULT_MTU;
    ec.daemon = 1;        /* By default run in daemon mode. */

#ifndef WIN32
    if(((pw = getpwnam("n2n")) != NULL) ||
       ((pw = getpwnam("nobody")) != NULL)) {
        ec.userid = pw->pw_uid;
        ec.groupid = pw->pw_gid;
    }
#endif

#ifdef WIN32
    ec.tuntap_dev_name[0] = '\0';
#else
    snprintf(ec.tuntap_dev_name, sizeof(ec.tuntap_dev_name), N2N_EDGE_DEFAULT_DEV_NAME);
#endif
    snprintf(ec.netmask, sizeof(ec.netmask), N2N_EDGE_DEFAULT_NETMASK);

    if((argc >= 2) && (argv[1][0] != '-')) {
        rc = loadFromFile(argv[1], &conf, &ec);
        if(argc > 2)
            rc = loadFromCLI(argc, argv, &conf, &ec);
    } else if(argc > 1)
        rc = loadFromCLI(argc, argv, &conf, &ec);
    else
#ifdef WIN32
        /* Load from current directory */
        rc = loadFromFile("edge.conf", &conf, &ec);
#else
        rc = -1;
#endif

    if(conf.transop_id == N2N_TRANSFORM_ID_NULL) {
        if(conf.encrypt_key) {
            /* make sure that AES is default cipher if key only (and no cipher) is specified */
            traceEvent(TRACE_WARNING, "Switching to AES as key was provided.");
            conf.transop_id = N2N_TRANSFORM_ID_AES;
        }
    }

    if(rc < 0)
        help();

    if(edge_verify_conf(&conf) != 0)
        help();

    traceEvent(TRACE_NORMAL, "Starting n2n edge %s %s", PACKAGE_VERSION, PACKAGE_BUILDDATE);

#if defined(HAVE_OPENSSL_1_1)
    traceEvent(TRACE_NORMAL, "Using %s", OpenSSL_version(0));
#endif

    traceEvent(TRACE_NORMAL, "Using compression: %s.", compression_str(conf.compression));
    traceEvent(TRACE_NORMAL, "Using %s cipher.", transop_str(conf.transop_id));

    /* Random seed */
    n2n_srand (n2n_seed());

#ifndef WIN32
    /* If running suid root then we need to setuid before using the force. */
    if(setuid(0) != 0)
        traceEvent(TRACE_ERROR, "Unable to become root [%u/%s]", errno, strerror(errno));
    /* setgid(0); */
#endif

    if(conf.encrypt_key && !strcmp((char*)conf.community_name, conf.encrypt_key))
        traceEvent(TRACE_WARNING, "Community and encryption key must differ, otherwise security will be compromised");

    if((eee = edge_init(&conf, &rc)) == NULL) {
        traceEvent(TRACE_ERROR, "Failed in edge_init");
        exit(1);
    }
    memcpy(&(eee->tuntap_priv_conf), &ec, sizeof(ec));

    if((0 == strcmp("static", eee->tuntap_priv_conf.ip_mode)) ||
         ((eee->tuntap_priv_conf.ip_mode[0] == '\0') && (eee->tuntap_priv_conf.ip_addr[0] != '\0'))) {
        traceEvent(TRACE_NORMAL, "Use manually set IP address.");
        eee->conf.tuntap_ip_mode = TUNTAP_IP_MODE_STATIC;
    } else if(0 == strcmp("dhcp", eee->tuntap_priv_conf.ip_mode)) {
        traceEvent(TRACE_NORMAL, "Obtain IP from other edge DHCP services.");
        eee->conf.tuntap_ip_mode = TUNTAP_IP_MODE_DHCP;
    } else {
        traceEvent(TRACE_NORMAL, "Automatically assign IP address by supernode.");
        eee->conf.tuntap_ip_mode = TUNTAP_IP_MODE_SN_ASSIGN;
        do {
            fd_set socket_mask;
            struct timeval wait_time;

            update_supernode_reg(eee, time(NULL));
            FD_ZERO(&socket_mask);
            FD_SET(eee->udp_sock, &socket_mask);
            wait_time.tv_sec = SOCKET_TIMEOUT_INTERVAL_SECS;
            wait_time.tv_usec = 0;

            if(select(eee->udp_sock + 1, &socket_mask, NULL, NULL, &wait_time) > 0) {
                if(FD_ISSET(eee->udp_sock, &socket_mask)) {
                    readFromIPSocket(eee, eee->udp_sock);
                }
            }
        } while(eee->sn_wait);
        eee->last_register_req = 0;
    }

    if(tuntap_open(&tuntap, eee->tuntap_priv_conf.tuntap_dev_name, eee->tuntap_priv_conf.ip_mode,
                   eee->tuntap_priv_conf.ip_addr, eee->tuntap_priv_conf.netmask,
                   eee->tuntap_priv_conf.device_mac, eee->tuntap_priv_conf.mtu) < 0) exit(1);
    traceEvent(TRACE_NORMAL, "Local tap IP: %s, Mask: %s",
               eee->tuntap_priv_conf.ip_addr, eee->tuntap_priv_conf.netmask);
    memcpy(&eee->device, &tuntap, sizeof(tuntap));
    //hexdump((unsigned char*)&tuntap,sizeof(tuntap_dev));

#ifndef WIN32
    if(eee->tuntap_priv_conf.daemon) {
        setUseSyslog(1); /* traceEvent output now goes to syslog. */
        daemonize();
    }
#endif /* #ifndef WIN32 */

#ifndef WIN32

#ifdef HAVE_LIBCAP
    /* Before dropping the privileges, retain capabilities to regain them in future. */
    caps = cap_get_proc();

    cap_set_flag(caps, CAP_PERMITTED, num_cap, cap_values, CAP_SET);
    cap_set_flag(caps, CAP_EFFECTIVE, num_cap, cap_values, CAP_SET);

    if((cap_set_proc(caps) != 0) || (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) != 0))
        traceEvent(TRACE_WARNING, "Unable to retain permitted capabilities [%s]\n", strerror(errno));
#else
#ifndef __APPLE__
    traceEvent(TRACE_WARNING, "n2n has not been compiled with libcap-dev. Some commands may fail.");
#endif
#endif /* HAVE_LIBCAP */

    if((eee->tuntap_priv_conf.userid != 0) || (eee->tuntap_priv_conf.groupid != 0)) {
        traceEvent(TRACE_NORMAL, "Dropping privileges to uid=%d, gid=%d",
                   (signed int)eee->tuntap_priv_conf.userid, (signed int)eee->tuntap_priv_conf.groupid);

        /* Finished with the need for root privileges. Drop to unprivileged user. */
        if((setgid(eee->tuntap_priv_conf.groupid) != 0)
           || (setuid(eee->tuntap_priv_conf.userid) != 0)) {
            traceEvent(TRACE_ERROR, "Unable to drop privileges [%u/%s]", errno, strerror(errno));
            exit(1);
        }
    }

    if((getuid() == 0) || (getgid() == 0))
        traceEvent(TRACE_WARNING, "Running as root is discouraged, check out the -u/-g options");
#endif

#ifdef __linux__
    signal(SIGTERM, term_handler);
    signal(SIGINT,  term_handler);
#endif
#ifdef WIN32
    SetConsoleCtrlHandler(term_handler, TRUE);
#endif

    keep_on_running = 1;
    traceEvent(TRACE_NORMAL, "edge started");
    rc = run_edge_loop(eee, &keep_on_running);
    print_edge_stats(eee);

#ifdef HAVE_LIBCAP
    /* Before completing the cleanup, regain the capabilities as some
     * cleanup tasks require them (e.g. routes cleanup). */
    cap_set_flag(caps, CAP_EFFECTIVE, num_cap, cap_values, CAP_SET);

    if(cap_set_proc(caps) != 0)
        traceEvent(TRACE_WARNING, "Could not regain the capabilities [%s]\n", strerror(errno));

    cap_free(caps);
#endif

    /* Cleanup */
    edge_term_conf(&eee->conf);
    tuntap_close(&eee->device);
    edge_term(eee);

#ifdef WIN32
    destroyWin32();
#endif

    return(rc);
}

/* ************************************** */