sipa · Emzy · Sep 28, 2020 · Sjors · Aug 21, 2023 · Sjors
diff --git a/README-dnssec.md b/README-dnssec.md
@@ -0,0 +1,299 @@
+# DNSSEC setup for dnsseed
+
+##### Table of Contents  
+[Requirements](#Requirements)  
+[Software needed](#Software)  
+[Setup](#Setup)  
+[Testing](#Testing)  
+[Example](#Example)  
+[Improvements](#Improvements)  
+[Links](#Links)  
+
+
+<a name="Requirements"/>
+
+## Recommendation
+* run only this service on the host (security precaution)
+
+<a name="Software"/>
+
+## Software needed
+
+* Debian GNU/Linux 10
+* tor
+* bind9
+* dig (debian package bind9-dnsutils)
+* nsupdate (debian package bind9-dnsutils)
+* bitcoin-seeder
+* ufw
+* bash
+
+```
+apt update
+apt install bind9 bind9-dnsutils bind9utils ufw tor
+```
+
+<a name="Setup"/>
+
+## Setup
+
+### ufw
+Configure and enable firewall
+```
+ufw allow 22/tcp
+ufw allow 53/udp
+ufw allow 53/tcp
+ufw enable
+ufw status
+```
+
+### Configuring Bind9
+Replace `example.com` with your domain.
+
+* add or change in /etc/bind/named.conf.options 
+```
+        querylog no;
+	allow-transfer { none; };
+	dnssec-enable yes;
+```
+
+* add to /etc/bind/named.conf.local 
+```
+zone "dnsseed.example.com" {
+      type master;
+      file "/var/lib/bind/db.dnsseed.example.com";
+      key-directory "/var/lib/bind";
+      allow-update {localhost;};
+      auto-dnssec maintain;
+      inline-signing yes;
+};
+```
+
+* Generate new file /var/lib/bind/db.example.com
+```
+$ORIGIN .
+$TTL 3600       ; 1 hour
+dnsseed.example.com.        IN SOA  dnsseed-host.example.com. contact-email.example.com. (
+                                2000000001 ; serial
+                                3600       ; refresh (1 hour)
+                                600        ; retry (10 minutes)
+                                86400      ; expire (1 day)
+                                600        ; minimum (10 minutes)
+                                )
+                        NS      dnsseed-host.example.com.
+dummy                   A       127.0.0.1
+```
+
+* Check config
+```
+named-checkconf
+named-checkzone dnsseed.example.com /var/lib/bind/db.dnsseed.example.com
+```
+
+* Restart Bind9
+`service bind9 restart`
+
+* Generate DNSSEC keys
+```
+cd /var/lib/bind
+dnssec-keygen -r /dev/urandom -a ECDSAP256SHA256 dnsseed.example.com`
+dnssec-keygen -r /dev/urandom -a ECDSAP256SHA256 -b 2048 -fKSK -n ZONE dnsseed.example.com
+chown bind: Kdnsseed.example.com*.key
+```
+
+* Add keys to zone file
+```
+cd /var/lib/bind
+for key in Kdnsseed.example.com*.key
+do
+echo "\$INCLUDE $key">> db.example.com
+done
+```
+
+* Sign zone
+```
+dnssec-signzone -A -3 $(head -c 1000 /dev/random | sha1sum | cut -b 1-16) -N INCREMENT -o example.com -t db.example.com
+```
+
+* Restart Bind9
+`service bind9 restart`
+
+* after the restart you will have a file /var/lib/bind/dsset-dnsseed.example.com.
+This file contains the DS records that need to be entered in the parent dns zone or in your domain registrar’s control panel.
+
+
+### Building bitcoin-seeder (should be non root)
+
+* Install requirements
+```
+sudo apt-get install build-essential libboost-all-dev libssl-dev
+```
+
+* Download
+```
+git pull https://github.com/sipa/bitcoin-seeder.git
+```
+
+* Compile
+```
+make
+```
+
+* Start
+```
+./dnsseed -p5353 -h dnsseed.example.com -n dnsseed-host.example.com -m someting.example.com -o 127.0.0.1:9050 
+```
+
+**TODO** systemd service
+
+### Cron script to fetch dns records from bitcoin-seeder
+
+* Download the file 
+
+[/etc/cron.hourly/dnsupdate](contrib/dnsupdate)
+
+* Put it in /etc/cron.hourly/
+
+* Change following line
+
+`ZONE=dnsseed.example.com`
+
+* Make it executable
+`chmod +x /etc/cron.daily/dnsupdate`
+
+<a name="Testing"/>
+
+## Testing
+
+* Checking if RRSIG record is present 
+```
+dig A dnsseed.emzy.de @8.8.8.8 +noadditional +dnssec +multiline
+dig AAAA dnsseed.emzy.de @8.8.8.8 +noadditional +dnssec +multiline
+dig A x49.dnsseed.emzy.de. +dnssec @8.8.8.8 +dnssec +multiline
+dig AAAA x49.dnsseed.emzy.de. +dnssec @8.8.8.8 +dnssec +multiline
+```
+
+* Check if all looks good on
+https://dnsviz.net/d/dnsseed.emzy.de/dnssec/
+
+* Check syslog that nsupdate is working
+/var/log/syslog should have many `updating zone` entries and a `zone ... (signed)` entry every hour.
+```
+...named[99]: client @0x7fd78048c650 127.0.0.1#41161: updating zone 'dnsseed.emzy.de/IN': adding an RR at 'x40c.dnss
+eed.emzy.de' A 134.209.232.105
+...named[99]: client @0x7fd7800b8520 127.0.0.1#58337: updating zone 'dnsseed.example.com/IN': adding an RR at 'x448.dnsseed.example.com' AAAA 2600:1f16:625:e00:aefd:9cc7:d3:6e86
+[...]
+...named[99]: zone dnsseed.emzy.de/IN (signed): serial 2000002744 (unsigned 2000002740)
+[...]
+```
+
+* * *
+<a name="Example"/>
+
+## Example (Debian 10)
+
+### bitcoin-seeder
+
+* Should look like this
+```
+user@dnsseed:~/bitcoin-seeder$ ./dnsseed -p5353 -h dnsseed.example.com -n dnsseed-host.example.com -m someting.example.com -o 127.0.0.1:9050
+Supporting whitelisted filters: 0x1,0x5,0x9,0xd,0x49,0x400,0x404,0x408,0x40c,0x448
+Using Tor proxy at 127.0.0.1:9050
+Loading dnsseed.dat...done
+Starting 4 DNS threads for dnsseed.example.com on dnsseed-host.example.com (port 5353).......done
+Starting seeder...done
+[20-09-18 13:02:55] 5733/36914 available (34970 tried in 1332s, 408 new, 1536 active), 55236 banned; 112 DNS requests, 44 db queries
+```
+
+### Bind9 full config files 
+
+* /etc/bind/named.conf.options
+```
+options {
+        directory "/var/cache/bind";
+
+        // If there is a firewall between you and nameservers you want
+        // to talk to, you may need to fix the firewall to allow multiple
+        // ports to talk.  See http://www.kb.cert.org/vuls/id/800113
+
+        // If your ISP provided one or more IP addresses for stable 
+        // nameservers, you probably want to use them as forwarders.  
+        // Uncomment the following block, and insert the addresses replacing 
+        // the all-0's placeholder.
+
+        // forwarders {
+        //      0.0.0.0;
+        // };
+
+        //========================================================================
+        // If BIND logs error messages about the root key being expired,
+        // you will need to update your keys.  See https://www.isc.org/bind-keys
+        //========================================================================
+        dnssec-validation auto;
+
+        listen-on-v6 { any; };
+       // hide version number from clients for security reasons.
+        version "not currently available";
+
+        // disable recursion on authoritative DNS server.
+        recursion no;
+
+        // disable the query log
+        querylog no;
+
+        // disallow zone transfer
+        allow-transfer { none; };
+
+        dnssec-enable yes;
+};
+```
+
+* /etc/bind/named.conf.local
+```
+//
+// Do any local configuration here
+//
+
+// Consider adding the 1918 zones here, if they are not used in your
+// organization
+//include "/etc/bind/zones.rfc1918";
+
+zone "dnsseed.emzy.de" {
+      type master;
+      file "/var/lib/bind/db.dnsseed.emzy.de";
+      key-directory "/var/lib/bind";
+      allow-update {localhost;};
+      auto-dnssec maintain;
+      inline-signing yes;
+};
+```
+
+* /var/lib/bind/db.example.com
+```
+$ORIGIN .
+$TTL 3600       ; 1 hour
+dnsseed.example.com.        IN SOA  dnsseed-host.example.com. contact-email.example.com. (
+                                2000000001 ; serial
+                                3600       ; refresh (1 hour)
+                                600        ; retry (10 minutes)
+                                86400      ; expire (1 day)
+                                600        ; minimum (10 minutes)
+                                )
+                        NS      dnsseed-host.example.com.
+dummy                   A       127.0.0.1
+dnsseed.example.com. IN DNSKEY 257 3 13 euXp/lPIx...xuSVYZ clx...xM==
+dnsseed.example.com. IN DNSKEY 256 3 13 6CNJQx...xykHv XKx...xg==
+```
+
+
+<a name="Improvements"/>
+
+## Possible improvements
+* enable key only authentication on ssh
+* use different SSH port (don't forget to add to ufw)
+* non root cron job and key for the nsupdate authentication
+
+<a name="Links"/>
+
+## Links
+* https://www.digitalocean.com/community/tutorials/how-to-setup-dnssec-on-an-authoritative-bind-dns-server--2
diff --git a/contrib/dnsupdate b/contrib/dnsupdate
@@ -0,0 +1,42 @@
+#!/bin/bash
+# This queries the bitcoin-seeder via dns on port 5353 and 
+# puts the result in the dns zone of a Bind9.
+# bitcoin-seeder: https://github.com/sipa/bitcoin-seeder
+
+set -euo pipefail
+
+# Zone to request from bintcoin-seeder
+ZONE=dnsseed.emzy.de
+# Filters to fetch
+FILTERS='x1 x5 x9 xd x49 x400 x404 x408 x40c x448'
+
+# Fetch and update A and AAAA records @ of the zone
+(
+  echo server localhost
+  echo zone ${ZONE}
+  echo update delete ${ZONE} a
+  echo update delete ${ZONE} aaaa
+  for proto in A AAAA ; do
+        dig +noall +answer -t ${proto} -p 15353 @52.37.101.214 ${ZONE} | \
+        awk '{ print "update add "$1" 3600 "$4" "$5"" }'
+
+  done
+  echo send
+) | \
+nsupdate -v
+
+# Fetch and update A and AAAA records of all available FILTER domain names
+for filter in ${FILTERS} ; do
+        (
+          echo server localhost
+          echo zone ${ZONE}
+          echo update delete ${filter}.${ZONE} a
+          echo update delete ${filter}.${ZONE} aaaa
+          for proto in A AAAA ; do
+                dig +noall +answer -t ${proto} -p 15353 @52.37.101.214 ${filter}.${ZONE} | \
+                awk '{ print "update add "$1" 3600 "$4" "$5"" }'
+          done
+          echo send
+        ) | \
+        nsupdate -v
+done