unwinder

Simple unwind drop-in replacement for unbound

ideal for tiny routers

About

unbound(8) is a validating DNS resolver with complex configurations well suited for datacenter.

unwind(8) is a simple validating DNS resolver wizard.

It's time to unwind.

Why

• lower DNS latency
• free RAM
• keep existing DNS blocking lists and exceptions ^{[1] [2]}

How

relayd(8) forwards DNS traffic between a client and unwind(8) using unpredictable requested IDs in the DNS header.

unwind(8) queries its recursor, a DoT forwarder, or an authoritative nameserver.

Features

• lightweight
• fast
• simple configuration
• sane defaults
• best practice recursor
• automatic cache
• efficient blocking list
• residential home.arpa. network support

Getting started

Include and configure pf.conf.unwinder

pfctl -f /etc/pf.conf

Install and configure myname

Install and configure nsd.conf

Install and configure the master zones

nsd-control-setup
rcctl restart nsd

Install and configure the unwind-block list fetcher and daily.local updates.

echo badexample.com > /var/db/unwind-block.txt.local
/usr/local/bin/unwind-block > /var/db/unwind-block.txt

Install and configure the unwind-unblock exceptions and daily.local updates.

echo example.com > /var/db/unwind-unblock.txt
/usr/local/bin/unwind-unblock > /var/db/unwind-block.txt.clean
mv /var/db/unwind-block.txt.clean /var/db/unwind-block.txt

Install and configure the egress interface

cp src/etc/hostname.if /etc/hostname.em0
sh /etc/netstart em0

Install resolv.conf

Enable dhcpleased and resolvd on -release or -stable

rcctl enable dhcpleased resolvd
rcctl start dhcpleased resolvd

Install and configure unwind.conf

rcctl enable unwind
rcctl restart unwind

Install and configure TLS certificates for DoT

n.b. To use DoT e.g. on a laptop, configure its unwind

# $OpenBSD: unwind.conf

# Macros

v4unwinder="10.0.0.1 authentication name unwinder.example.com DoT"
v6unwinder="fd80:a:b:c::1 authentication name unwinder.example.com DoT"

# Global Configuration

forwarder {
 $v4unwinder
 $v6unwinder
}

preference DoT

Install and configure relayd.conf

rcctl restart relayd

Install and configure dhcpd.conf

rcctl restart dhcpd

Install and configure rad.conf

rcctl restart rad

Preview

$ du -h /var/db/unwind-block.txt
12.4M   /var/db/unwind-block.txt

$ unwindctl status memory 
msg-cache:   76198 / 1048576 (7.27%)
rrset-cache: 228898 / 1048576 (21.83%)
key-cache: 34504 / 1048576 (3.29%)
neg-cache: 14212 / 102400 (13.88%)

$ ps aux -U _unwind                                                                            
USER       PID %CPU %MEM   VSZ   RSS TT  STAT   STARTED       TIME COMMAND
_unwind  10938  0.0  0.4 16824 15980 ??  IpU    26Jun21   34:30.76 unwind: resolver (unwind)
_unwind  19822  0.0  1.6 65644 66052 ??  Ip     26Jun21   13:35.89 unwind: frontend (unwind)

$ fstat -u _unwind -n
USER     CMD          PID   FD  DEV      INUM        MODE   R/W    SZ|DV
_unwind  unwind     19822   wd  4,57   207368        40755    r      512
_unwind  unwind     19822 root  4,57   207368        40755    r      512
_unwind  unwind     19822    0  4,48    17811        20666   rw    2,2  
_unwind  unwind     19822    1  4,48    17811        20666   rw    2,2  
_unwind  unwind     19822    2  4,48    17811        20666   rw    2,2  
_unwind  unwind     19822    3* unix stream 0x0
_unwind  unwind     19822    4 kqueue 0x0 0 state: W
_unwind  unwind     19822    5* unix stream 0x0
_unwind  unwind     19822    6* internet dgram udp 127.0.0.1:53
_unwind  unwind     19822    7* internet6 dgram udp [::1]:53
_unwind  unwind     19822    8* internet stream tcp 0x0 127.0.0.1:53
_unwind  unwind     19822    9* internet6 stream tcp 0x0 [::1]:53
_unwind  unwind     19822   10  4,57   129757       100644   rw      376
_unwind  unwind     19822   11* unix stream 0x0 /dev/unwind.sock
_unwind  unwind     19822   12* route raw 0 0x0
_unwind  unwind     19822   13* unix stream 0x0 /dev/unwind.sock
_unwind  unwind     10938   wd  4,48    49761        40700    r      512
_unwind  unwind     10938    0  4,48    17811        20666   rw    2,2  
_unwind  unwind     10938    1  4,48    17811        20666   rw    2,2  
_unwind  unwind     10938    2  4,48    17811        20666   rw    2,2  
_unwind  unwind     10938    3* unix stream 0x0
_unwind  unwind     10938    4 kqueue 0x0 0 state: W
_unwind  unwind     10938    5* unix stream 0x0

Caveats

Some public DNS resolvers (e.g. Google, Cloudflare) provide a response to DNS forward queries for home.arpa from IANA blackhole servers.

As a feature, unwind provides a negative response to DNS reverse-mapping queries for IP addresses that are not globally unique i.e. AS112 zones

Split-horizon DNS is not supported. A redirection and reflection is used for connecting to the external address of the firewall from a host on the LAN.