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Thread: ubuntu 16.04.6 LTS how to turn off default ports

  1. #1
    Join Date
    Feb 2016
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    7

    ubuntu 16.04.6 LTS how to turn off default ports

    hello team:

    i just installed ubuntu 16.04 and found out a lot of ports opened by default. how could i turn those ports off?

    Code:
    user@home:~:$ nmap -Pn 192.168.1.10
    Starting Nmap 7.80 ( https://nmap.org ) at 2019-10-13 23:13 EDT
    Nmap scan report for 192.168.1.10
    Host is up (0.0079s latency).
    Not shown: 984 filtered ports
    PORT      STATE SERVICE
    1/tcp     open  tcpmux
    53/tcp    open  domain
    79/tcp    open  finger
    111/tcp   open  rpcbind
    119/tcp   open  nntp
    143/tcp   open  imap
    1080/tcp  open  socks
    1524/tcp  open  ingreslock
    2000/tcp  open  cisco-sccp
    6667/tcp  open  irc
    12345/tcp open  netbus
    31337/tcp open  Elite
    32771/tcp open  sometimes-rpc5
    32772/tcp open  sometimes-rpc7
    32773/tcp open  sometimes-rpc9
    32774/tcp open  sometimes-rpc11
    
    
    Nmap done: 1 IP address (1 host up) scanned in 5.77 seconds
    Last edited by DuckHook; October 14th, 2019 at 05:05 AM. Reason: Added [CODE] tags.

  2. #2
    Join Date
    Mar 2011
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    Ubuntu 18.04 Bionic Beaver

    Re: ubuntu 16.04.6 LTS how to turn off default ports

    Thread moved to Security as the more appropriate forum.

    I recommend that you read the link in my sig: "Security Basics"

    The usual method used to configure ports is UFW (Uncomplicated FireWall). The graphical equivalent is GUFW. UFW is the firewall configuration tool already built into Ubuntu. GUFW is available in the repos as a simple download. It is nothing more than a graphical front end for UFW.

    You need to be careful closing ports. Doing so may break functions that you may not realize are needed. For example, 119 is needed for network time sync. 143 is needed for your e-mail client. If you run IRC or have a client with that functionality, it will open a high port like 6667.

    Your instincts are good. It is good practice to lock down everything and open only those ports that you know are needed. Just go about them one at a time and test thoroughly for broken functionality to avoid breakage and frustration.

    Good Luck and Happy Ubuntuing!

  3. #3
    Join Date
    Feb 2016
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    7

    Re: ubuntu 16.04.6 LTS how to turn off default ports

    thanks for advice. i will turn the UFW on later.

    but i would like to turn some ports off such as 119, 79, 12345 etc. i really don't want people to finger my server, also am not sure i would ever run a network news server on this machine. that thing is a target for hackers, besides my bandwidth will be clogged with traffic.

  4. #4
    Join Date
    Feb 2010
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    Xubuntu 18.04 Bionic Beaver

    Re: ubuntu 16.04.6 LTS how to turn off default ports

    Quote Originally Posted by dave219 View Post
    thanks for advice. i will turn the UFW on later.

    but i would like to turn some ports off such as 119, 79, 12345 etc. i really don't want people to finger my server, also am not sure i would ever run a network news server on this machine. that thing is a target for hackers, besides my bandwidth will be clogged with traffic.
    Once you turn on UFW, those ports will not be visible to other hosts, unless you specifically allow them in a rule. I'd recommend checking out the security sticky threads.

    You may also uninstall the services running those ports.

  5. #5
    Join Date
    Mar 2010
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    Ubuntu Mate 16.04 Xenial Xerus

    Re: ubuntu 16.04.6 LTS how to turn off default ports

    I've never seen a stock Ubuntu Server step anything I didn't request at the install with a listener. I always only install the ssh-server and nothing else at install time. Doing that, only 22/tcp is listening. Nothing else.

    Did you install a stock Ubuntu Server from a reputable location or was it something else?

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