The generic-seeder app is a crawler that can easily be customized for almost any blockchain network. It generates a list of nodes on the network and the most reliable nodes can be exposed via a built-in DNS server or pushed to a remote CloudFlare server.
Features:
- Regularly revisits known nodes to check their availability
- CloudFlare DNS integration
- Block explorer integration (including support for a 2nd failover explorer)
- Keep a running list of all nodes in the network or only show nodes that are above a certain version
- Bans/Unlists nodes after enough failures, or bad behaviour
- 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
- Run multiple crawlers at the same time (96 threads simultaneously by default)
- Force connections to IPv4 or IPv6 only if desired
- Customizable options via configuration file
Detailed set up instructions can be found in the DNS Seeder Setup Guide
sudo apt-get install build-essential libboost-all-dev libssl-dev libcurl4-openssl-dev libconfig++-dev
cp ./settings.conf.template ./settings.conf
Make required changes in settings.conf
Compiling will require boost and ssl. On debian systems, these are provided
by libboost-dev and libssl-dev respectively.
make
This will produce the dnsseed binary.
For example, if you want to run a DNS seed on dnsseed.example.com, you will need an authorative NS record in example.com's domain record that points back to your server. It is required to create both an NS and "A" record to tie everything together.
| Record Type | Name/Host | Value/Nameserver |
|---|---|---|
| A | vps | 123.231.123.231 |
| NS | dnsseed | vps.example.com |
On the system vps.example.com, you can now run the seeder app as the root user:
sudo ./dnsseed -h dnsseed.example.com -n vps.example.com
If you want the DNS server to report SOA records, you must provide an email address using the -m argument:
./dnsseed -h dnsseed.example.com -n vps.example.com -m email@example.com
There are two known options for running the seeder app using a non-root user:
- The first non-root method is to use the
setcapcommand to change the capabilities of thednsseedbinary file to specifically allow the app to bind to a port less than 1024 (this one-time cmd requires root privileges):
sudo setcap 'cap_net_bind_service=+ep' /path/to/dnsseed
Once the setcap command is complete, you can start the seeder app as per normal, without the need for sudo:
./dnsseed -h dnsseed.example.com -n vps.example.com -m email@example.com
- The second non-root method is to add a redirect entry for port 53 in the iptables firewall system before running the seeder app as a non-root user (this one-time cmd requires root privileges):
sudo iptables -t nat -A PREROUTING -p udp --dport 53 -j REDIRECT --to-port 5353
After adding the new iptables rule, the seeder app can be called without sudo, but you must always specify the redirected port using the -p argument:
./dnsseed -h dnsseed.example.com -n vps.example.com -m email@example.com -p 5353
Extra setup is required before CloudFlare mode will work properly. Python 3+ and the Cloudflare Python API must be installed. Run the following cmds in the terminal, one line at a time:
sudo apt-get install python3 python3-pip
sudo pip3 install cloudflare
You must also fill in the CloudFlare API config section at the bottom of the settings.conf file.
Example:
cf_domain="example.com"
cf_domain_prefix="dnsseed"
cf_username="your_cloudflare_username"
cf_api_key="your_cloudflare_api_key"
cf_seed_dump="dnsseed.dump"
Have the seeder above running all the time, but with no NS record:
./dnsseed
After a few minutes of running the generic seeder and the dnsseed.dump file has been populated you can then test CloudFlare mode:
cd /path/to/seeder/cf-uploader && python3 seeder.py
Assuming no errors were reported, you can check that your seeder domain is
working properly by running the following cmd in the format
nslookup {cf_domain_prefix}.{cf_domain}:
nslookup dnsseed.example.com
If everything is working correctly, you will see a number of "Name:" and "Address:" lines near the end of the output:
Server: 2001:19f1:300:1702::3
Address: 2001:19f1:300:1702::3#53
Non-authoritative answer:
Name: dnsseed.example.com
Address: 158.203.13.138
Name: dnsseed.example.com
Address: 44.76.38.113
Name: dnsseed.example.com
Address: 46.76.253.117
Name: dnsseed.example.com
Address: 145.248.52.149
Name: dnsseed.example.com
Address: 82.240.23.104
Name: dnsseed.example.com
Address: 103.207.140.36
Name: dnsseed.example.com
Address: 204.222.30.68
Once configured correctly, it is recommended to set up a cron job that will automatically update the seeds list every 30 minutes or so:
*/30 * * * * cd /path/to/seeder/cf-uploader && python3 seeder.py
Need more help? Read the DNS Seeder Setup Guide