ccbc-seeder

ccbc-seeder is a crawler for the ccbc 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 v0.5.0 to request new IP addresses from, but only reports good post-v0.6.9 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 96 threads simultaneously).

REQUIREMENTS

$ sudo apt-get install build-essential libboost-all-dev libssl-dev

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-mail address (with the @ part replaced by .) using -m.

COMPILING

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.

$ make clean

This will remove all precompiled .o files

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.

TESTING

You can test the DNS Records with.

$ dig -t A dnsseed.example.com

Should get a response:

; <<>> DiG 9.11.3-1ubuntu1.1-Ubuntu <<>> -t A dnsseed.example.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21606 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 65494 ;; QUESTION SECTION: ;dnsseed.ccbc.network. IN A

;; ANSWER SECTION: dnsseed.example.com. 2 IN A 139.99.34.233

The Ip will change as Request go on these are the crawled ips from running nodes.

Firewall

If you use ufw you need to enable port $ ufw allow 53