Running nmap on my localhost shows me strange open ports:
$ nmap -p- localhost
Starting Nmap 6.47 ( http://nmap.org ) at 2015-12-28 12:14 CET
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00047s latency).
All 65535 scanned ports on localhost (127.0.0.1) are closed
Nmap done: 1 IP address (1 host up) scanned in 2.51 seconds
$ nmap -p- localhost
Starting Nmap 6.47 ( http://nmap.org ) at 2015-12-28 12:14 CET
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00046s latency).
Not shown: 65533 closed ports
PORT STATE SERVICE
36642/tcp open unknown
50826/tcp open unknown
Nmap done: 1 IP address (1 host up) scanned in 2.55 seconds
$ nmap -p- localhost
Starting Nmap 6.47 ( http://nmap.org ) at 2015-12-28 12:14 CET
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00050s latency).
Not shown: 65531 closed ports
PORT STATE SERVICE
37700/tcp open unknown
46694/tcp open unknown
48334/tcp open unknown
53438/tcp open unknown
Nmap done: 1 IP address (1 host up) scanned in 2.60 seconds
$ nmap -p- localhost
Starting Nmap 6.47 ( http://nmap.org ) at 2015-12-28 12:14 CET
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00046s latency).
All 65535 scanned ports on localhost (127.0.0.1) are closed
Nmap done: 1 IP address (1 host up) scanned in 2.51 second
As this ouput shows, the open ports seem to change fast and randomly. I cannot see these ports via netstat if I am interpreting the output the right way:
$ sudo netstat -tulpen
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode PID/Program name
tcp 0 0 127.0.1.1:53 0.0.0.0:* LISTEN 0 17081 809/dnsmasq
udp 0 0 0.0.0.0:5449 0.0.0.0:* 0 30885 2855/dhclient
udp 0 0 127.0.1.1:53 0.0.0.0:* 0 17080 809/dnsmasq
udp 0 0 0.0.0.0:68 0.0.0.0:* 0 30321 2855/dhclient
udp 0 0 0.0.0.0:45170 0.0.0.0:* 107 15289 606/avahi-daemon: r
udp 0 0 0.0.0.0:631 0.0.0.0:* 0 15931 636/cups-browsed
udp 0 0 0.0.0.0:5353 0.0.0.0:* 107 15287 606/avahi-daemon: r
udp6 0 0 :::34146 :::* 107 15290 606/avahi-daemon: r
udp6 0 0 :::55654 :::* 0 30886 2855/dhclient
udp6 0 0 :::5353 :::* 107 15288 606/avahi-daemon: r
I tried to use lsof to investige these ports, but there is no result, I guess when nmap returns, the port is not open any longer:
lsof -i :`nmap -p- localhost|grep '/tcp'|cut -d'/' -f1|head -n1`
What can I do to further investigate this issue? Do I have to be worried? Is this normal? Should I suspect any malicious processes running?
Note that this Q&A is different as I am running everything on my local machine.
