README.md

columbus-dns

This repository is deprecated!

‼️ The server component is moved to https://github.com/elmasy-com/columbus.

---

A DNS server to collect domains to Columbus Server.

The goal of columbus-dns is to make it easy/possible for users to easily contribute to the Columbus Project.

By setting the DNS servers to columbus-dns while enumerationg subdomains, hunting bugs, etc you can contribute to the Columbus Project.

Design

                               _________________
  |---> dig exmaple.com A ---->| COLUMBUS-DNS  | -----> Insert -----> columbus.elmasy.com
  |                            -----------------
  ^                                   |
  |                                   V
Alice <------- 93.184.216.34 <---------

• Only domains with valid answer will be sent to the server (NOERROR)

IMPORTANT!

THIS SERVER IS NOT MEANT TO USED AS A DAILY DNS RESOLVER!

Install

The most secure way to run columbus-dns is to run as a non root user on a non-privileged port (eg.: 1053) and redirect traffic deisgnated to port 53.

nftables example:

table inet filter {
	chain inbound_ipv4 {
    ...
		tcp dport 1053 accept
		udp dport 1053 accept
	}

	chain inbound_ipv6 {
    ...
	}

	chain input {
		type filter hook input priority filter; policy drop;
		ct state { established, related } accept
		iifname "lo" accept
		meta protocol vmap { ip : jump inbound_ipv4, ip6 : jump inbound_ipv6 }
		tcp dport 22 accept
		reject
	}

  ...
}

table ip nat {
	chain prerouting {
		type nat hook prerouting priority filter; policy accept;
		udp dport 53 redirect to :1053
		tcp dport 53 redirect to :1053
	}

	chain postrouting {
		type nat hook postrouting priority filter; policy accept;
	}
}

The checksum file is signed with key 10BC80B36072944B5678AF395D00FD9E9F2A3725.

gpg --receive-key 10BC80B36072944B5678AF395D00FD9E9F2A3725

1. Create the user:

adduser --no-create-home --disabled-login "columbus-dns"

2. Install (and edit if needed) columbus-dns.service:

wget -q -O "columbus-dns.service" "https://raw.githubusercontent.com/elmasy-com/columbus-dns/main/columbus-dns.service"

mv columbus-dns.service /etc/systemd/system/

3. Install and edit columbus-dns.conf

mkdir /etc/columbus

wget -q -O "columbus-dns.conf" "https://raw.githubusercontent.com/elmasy-com/columbus-dns/main/columbus-dns.conf"

sudo mv columbus-dns.conf /etc/columbus/dns.conf

chown columbus-dns:columbus-dns /etc/columbus/dns.conf

sudo chmod 0640 /etc/columbus/dns.conf

nano /etc/columbus/dns.conf

4. Install the binary:

For Linux/AMD64:

wget -q 'https://github.com/elmasy-com/columbus-dns/releases/latest/download/columbus-dns-linux-amd64' -O columbus-dns-linux-amd64 && \
wget -q 'https://github.com/elmasy-com/columbus-dns/releases/latest/download/checksums' -O checksums && \
gpg --verify checksums && sha512sum --ignore-missing -c checksums && rm checksums && \
sudo install columbus-dns-linux-amd64 /usr/bin/columbus-dns

5. Start the service

sudo systemctl daemon-reload

sudo systemctl enable --now columbus-dns.service