When trying to establish a TCP connection to my IP address,, netcat tells me that the host isn't authorative. That is,

[~] $ echo "Hello, world"|nc -c -vv 8080 & nc -l -p 8080
Warning: Host isn't authoritative! (direct lookup mismatch) -> feross  BUT  feross -> 8080 (http-alt) open
Hello, world
Total received bytes: 0
Total sent bytes: 13
Total received bytes: 13
Total sent bytes: 0


  • 1
    Broken reverse DNS in a LAN? What does host report? – Incnis Mrsi Sep 17 '15 at 16:47
  • @IncnisMrsi, $ host outputs Host not found: 3(NXDOMAIN) – Giuseppe Crinò Sep 17 '15 at 16:52
  • OK, then fgrep /etc/hosts – Incnis Mrsi Sep 17 '15 at 16:52
  • @IncnisMrsi, reports nothing – Giuseppe Crinò Sep 17 '15 at 16:55
  • What do you try to achieve with nc -c? – Incnis Mrsi Sep 17 '15 at 16:58

The message

Host isn't authoritative! (direct lookup mismatch) -> feross  BUT  feross ->

indicates that two specified BSD Sockets calls:

  • gethostbyaddr – returns "feross" on (IPv4)
  • gethostbyname – returns (IPv4) on "feross"

Assuming there is no in /etc/hosts and host fails, it might be caused by broken setup in /etc/host.conf, by an obscure poorly documented name resolver library, or by whatever.

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