FAQ

[CentOS] CentOS-6 firewall how to open a port

Timothy Murphy
Jul 17, 2011 at 11:39 am
I'm running CentOS-6 on an HP MicroServer (since this morning)
and I'd like to open an non-standard port,
for use on a laptop attached to the internet through the server.

Do I have to explicitly add an iptables rule?
If so, and I want to open (say) udp port 500 ,
what command should I give?

I've always used shorewall in the past,
and will probably do so now if the default firewall is difficult to use.
But I thought I would try it first as an experiment.

My recollection is that in old versions of CentOS
one could non-standard ports through system-config-firewall ;
but it seems that now this can only be used for standard ports;

I looked at <http://wiki.centos.org/HowTos/Network/IPTables>
but didn't find it very enlightening.

Any advice or suggestions gratefully received.




--
Timothy Murphy
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland
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5 responses

  • Ljubomir Ljubojevic at Jul 17, 2011 at 11:53 am

    Timothy Murphy wrote:
    I'm running CentOS-6 on an HP MicroServer (since this morning)
    and I'd like to open an non-standard port,
    for use on a laptop attached to the internet through the server.

    Do I have to explicitly add an iptables rule?
    If so, and I want to open (say) udp port 500 ,
    what command should I give?

    I've always used shorewall in the past,
    and will probably do so now if the default firewall is difficult to use.
    But I thought I would try it first as an experiment.

    My recollection is that in old versions of CentOS
    one could non-standard ports through system-config-firewall ;
    but it seems that now this can only be used for standard ports;

    I looked at <http://wiki.centos.org/HowTos/Network/IPTables>
    but didn't find it very enlightening.

    Any advice or suggestions gratefully received.
    Use System -> Administration -> Firewall from GUI.
    Or "/usr/bin/system-config-firewall" from SSH/console TUI.

    Ljubomir
  • David at Jul 17, 2011 at 12:05 pm

    At 08:53 AM 7/17/2011, you wrote:
    Timothy Murphy wrote:
    I'm running CentOS-6 on an HP MicroServer (since this morning)
    and I'd like to open an non-standard port,
    for use on a laptop attached to the internet through the server.
    (snip)

    Any advice or suggestions gratefully received.
    Use System -> Administration -> Firewall from GUI.
    Or "/usr/bin/system-config-firewall" from SSH/console TUI.

    Ljubomir
    I loaded my system with text-install and network, and find no file
    named "/usr/bin/system-config-firewall". My guess is that it comes
    with a package that I haven't installed. Can you identify that package?

    Thanks
    David
  • Rudi Ahlers at Jul 17, 2011 at 12:10 pm

    On Sun, Jul 17, 2011 at 6:05 PM, david wrote:
    At 08:53 AM 7/17/2011, you wrote:
    Timothy Murphy wrote:
    I'm running CentOS-6 on an HP MicroServer (since this morning)
    and I'd like to open an non-standard port,
    for use on a laptop ?attached to the internet through the server.
    (snip)

    Any advice or suggestions gratefully received.
    Use System -> Administration -> Firewall from GUI.
    Or "/usr/bin/system-config-firewall" from SSH/console TUI.

    Ljubomir
    I loaded my system with text-install and network, and find no file
    named "/usr/bin/system-config-firewall". ?My guess is that it comes
    with a package that I haven't installed. ?Can you identify that package?

    Thanks
    David

    _______________________________________________


    yum install system-config-network


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    Rudi Ahlers
    SoftDux

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  • Timothy Murphy at Jul 17, 2011 at 7:45 pm

    Timothy Murphy wrote:

    I'm running CentOS-6 on an HP MicroServer (since this morning)
    and I'd like to open an non-standard port,
    for use on a laptop attached to the internet through the server.

    Do I have to explicitly add an iptables rule?
    If so, and I want to open (say) udp port 500 ,
    what command should I give? ...
    My recollection is that in old versions of CentOS
    one could non-standard ports through system-config-firewall ;
    but it seems that now this can only be used for standard ports;
    Apologies.
    There is a perfectly clear option "Other Ports"
    on running system-config-firewall as root.

    There does seem to be a bug/feature: if you enter
    the same procedure by Administration=>Firewall (in KDE)
    you cannot make any changes (at least I could not)
    even after giving the superuser password, when requested.

    --
    Timothy Murphy
    e-mail: gayleard /at/ eircom.net
    tel: +353-86-2336090, +353-1-2842366
    s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland
  • Ljubomir Ljubojevic at Jul 18, 2011 at 5:40 am

    Timothy Murphy wrote:
    There does seem to be a bug/feature: if you enter
    the same procedure by Administration=>Firewall (in KDE)
    you cannot make any changes (at least I could not)
    even after giving the superuser password, when requested.
    You should reported as a bug, either to bugs.centos.org or on Red Hat's
    bugzilla.

    --

    Ljubomir Ljubojevic
    (Love is in the Air)
    PL Computers
    Serbia, Europe

    Google is the Mother, Google is the Father, and traceroute is your
    trusty Spiderman...
    StarOS, Mikrotik and CentOS/RHEL/Linux consultant

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