I have Ubuntu 14 opening many UDP ports. The avadi_daemon was listed as the owner of the process (Using Netstat). I turned that off, but they then spawned with no owner. I can even kill the process and it starts again using another port.

I don't know what app is doing this. Is there any way to put some kind of check or rule that says before opening port check?

I am using ufw enabled.

Regards, Wesley

  • Answer is here: askubuntu.com/questions/205937/… From the manpage: The Avahi mDNS/DNS-SD daemon implements Apple's Zeroconf architecture (also known as "Rendezvous" or "Bonjour"). The daemon registers local IP addresses and static services using mDNS/DNS-SD and provides two IPC APIs for local programs to make use of the mDNS record cache the avahi-daemon maintains. Little bit of search can not harm. – fugitive Feb 5 '17 at 22:28
  • Thanks, I read that information, but guess I didn't comprehend it. I just see 6 udp ports and non-users running --WARN-- [lin003w] The process `something' is listening on socket 0t0 (24236 on 0t0 interface) is run by 3606. {who is 3606) – Wesley Davidson Feb 5 '17 at 22:40
  • some of the udp are essential for a system to work properly. Each has it's own purpose. You can try to examine what each process does by looking to man pages. Simply man -k avahi and it will list up all manpages related to avahi. You can check your running UDP services with the netstat sudo netstat -ulpa. Edit your answer with the output of this command and let us know what you really want to turn off. – fugitive Feb 5 '17 at 22:46
  • udp 0 0 :63510 *: 5528/dhclient udp 0 0 xxxxx-xxxxxxxx-D:domain : 1236/dnsmasq udp 0 0 :bootpc *: 5528/dhclient udp 0 0 :31925 *: 3200/avahi-daemon: udp6 0 0 [::]:mdns [::]:* 3200/avahi-daemon: --- – Wesley Davidson Feb 5 '17 at 23:57
  • There are like 4 more that didn't have enough room. – Wesley Davidson Feb 5 '17 at 23:58

The documentation above provides good information. After using some investigation the dnsmasq had somehow configured itself to use two mdns servers. In addition, it looks like I had an uninvited guest.

Another interesting item, if you turn on ufw, you enable the mdns(adding the two mdns servers) and alter you iptables.

ufw -list iptables -L

ufw enable iptables -L.

I tested this on two of my Ubuntu Trusty Tahr 14 boxes.

Anyway, ufw modified iptables to allow comm to two mdns servers.

regards, Wes

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.