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PR-DNSd - Passive-Recursive DNS Daemon


Passive-Recursive DNS daemon.


Quickstart

nameserver 127.0.0.1 | sudo tee /etc/resolv.conf dig google.com dig -x $(dig +short google.com)">
go get github.com/korc/PR-DNSdsudo setcap cap_net_bind_service,cap_sys_chroot=ep go/bin/PR-DNSdgo/bin/PR-DNSd -upstream 9.9.9.9:53 -listen 127.0.0.1:53echo nameserver 127.0.0.1 | sudo tee /etc/resolv.confdig google.comdig -x $(dig +short google.com)

If you can't use setcap, you have to use -chroot "" and -listen :<high_port> options, or run as root.

Use cases

  • run as local host DNS service, to fix your netstat/tcpview/lsof etc. output
  • as enterprise-internal DNS server, to also be able to do meaningful EDR/IR and log analysis
  • as cloud service, to also collect Passive DNS data from non-enterprise (home, BYOD etc.) devices
    • hint: you probably want to configure DDoS protection options
  • in cloud as DNS-over-TLS server, to additionally provide private DNS for supporting devices (ex: Android 9's private DNS setting)
    • ex: domain pattern based firewall/proxy configuration for mobile devices

Running as your own private server for Android9's Private DNS settings

After appropriate setcap, run:

PR-DNSd -tlslisten :853 -cert YOUR_SERVER_CRT_KEY_PEM -upstream 1.1.1.1:53 -store pr-dnsd

Options

-cert string    TCP-TLS listener certificate (required for tls listener)-chroot string    chroot to directory after start (default "/var/tmp")-count int    Count of replies allowed before debounce delay is applied (default 100)-ctmout string    Client timeout for upstream queries-debounce string    Required time duration between UDP replies to single IP to prevent DoS (default "200ms")-key string    TCP-TLS certificate key (default same as -cert value)-listen string    listen address (default ":53")-silent    Don't report normal data-store string    Store PTR data to specified file-tlslisten string    TCP-TLS listener address (default ":853")-upstream string    upstream DNS serv   er (tcp-tls:// prefix for DoT) (default "1.1.1.1:53")    (with tls and chroot, ensure ca-certificates and resolv.conf in chroot are properly set up)


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