Commit 0195702c authored by Pieter Wuille's avatar Pieter Wuille
Browse files

help text

parent c00ca462
bitcoin-seeder
==============
Bitcoin-seeder is a crawler for the Bitcoin network, which exposes a list
of reliable nodes via a built-in DNS server.
Features:
* regularly revisits known nodes to check their availability
* bans nodes after enough failures, or bad behaviour
* accepts nodes down to v0.3.19 to request new IP addresses from,
but only reports good post-v0.3.24 nodes.
* keeps statistics over (exponential) windows of 2 hours, 8 hours,
1 day and 1 week, to base decisions on.
* very low memory (a few tens of megabytes) and cpu requirements.
* crawlers run in parallel (by default 24 threads simultaneously).
USAGE
-----
Assuming you want to run a dns seed on dnsseed.example.com, you will
need an authorative NS record in example.com's domain record, pointing
to for example vps.example.com:
$ dig -t NS dnsseed.example.com
;; ANSWER SECTION
dnsseed.example.com. 86400 IN NS vps.example.com.
On the system vps.example.com, you can now run dnsseed:
./dnsseed -h dnsseed.example.com -n vps.example.com
If you want the DNS server to report SOA records, please provide an
e-mailadres (with the @ part replaced by .) using -m.
RUNNING AS NON-ROOT
-------------------
Typically, you'll need root privileges to listen to port 53 (name service).
One solution is using an iptables rule (Linux only) to redirect it to
a non-privileged port:
$ iptables -t nat -A PREROUTING -p udp --dport 53 -j REDIRECT --to-port 5353
If properly configured, this will allow you to run dnsseed in userspace, using
the -p 5353 option.
......@@ -21,6 +21,19 @@ public:
CDnsSeedOpts() : nThreads(24), nPort(53), mbox(NULL), ns(NULL), host(NULL) {}
void ParseCommandLine(int argc, char **argv) {
static const char *help = "Bitcoin-seeder\n"
"Usage: %s -h <host> -n <ns> [-m <mbox>] [-t <threads>] [-p <port>]\n"
"\n"
"Options:\n"
"-h <host> Hostname of the DNS seed\n"
"-n <ns> Hostname of the nameserver\n"
"-m <mbox> E-Mail address reported in SOA records\n"
"-t <threads> Number of crawlers to run in parallel (default 24)\n"
"-p <port> UDP port to listen on (default 53)\n"
"-?, --help Show this text\n"
"\n";
bool showHelp = false;
while(1) {
static struct option long_options[] = {
{"host", required_argument, 0, 'h'},
......@@ -28,6 +41,7 @@ public:
{"mbox", required_argument, 0, 'm'},
{"threads", required_argument, 0, 't'},
{"port", required_argument, 0, 'p'},
{"help", no_argument, 0, 'h'},
{0, 0, 0, 0}
};
int option_index = 0;
......@@ -52,14 +66,23 @@ public:
case 't': {
int n = strtol(optarg, NULL, 10);
if (n > 0 && n < 1000) nThreads = n;
break;
}
case 'p': {
int p = strtol(optarg, NULL, 10);
if (p > 0 && p < 65536) nPort = p;
break;
}
case '?': {
showHelp = true;
break;
}
}
}
if (host == NULL || ns == NULL) showHelp = true;
if (showHelp) fprintf(stderr, help, argv[0]);
}
};
......@@ -175,6 +198,7 @@ int main(int argc, char **argv) {
}
if (!opts.host) {
fprintf(stderr, "No hostname set. Please use -h.\n");
exit(1);
}
FILE *f = fopen("dnsseed.dat","r");
if (f) {
......
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