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  • Firewall for Ubuntu 14.04 LTS
    09/01/2015 4:16PM

    For whatever reason, Ubuntu 14.04 does not seem to come with a firewall.

    There are however two packages which provide, both a firewall and a handy GUI front-end for it.  UncomplicatedFireWall is the main package (ufw) and the GUI is gufw.

    To install:

    # apt-get install gufw

    This will install the front-end and the dependent packages

    To turn it on:

    # ufw enable

    The default is to block all incoming traffic.

    To update and add your own firewall rules and allow incoming connections

    # gufw

    The GUI is quite intuitive and allows advanced users the ability to create their own custom rules.

  • Fixing Compile Error: undefined reference to 'dclose' (dlopen, dlsym, and/or dlerror)
    04/01/2013 8:29AM

    I am running an Ubuntu 12.10 machine and I had to compile and install a jsvc binary for an older version that I didn't have a package that I could install via dpkg or apt-get install.

    Running configure came off without a hitch.

    Running make resulted in the following error:

    gcc -ldl -lpthread jsvc-unix.o libservice.a -o ../jsvc
    libservice.a(dso-dlfcn.o): In function `dso_unlink':
    /usr/local/src/daemon-1.0.1/src/native/unix/native/dso-dlfcn.c:41: undefined reference to `dlclose'
    libservice.a(dso-dlfcn.o): In function `dso_link':
    /usr/local/src/daemon-1.0.1/src/native/unix/native/dso-dlfcn.c:36: undefined reference to `dlopen'
    libservice.a(dso-dlfcn.o): In function `dso_symbol':
    /usr/local/src/daemon-1.0.1/src/native/unix/native/dso-dlfcn.c:47: undefined reference to `dlsym'
    libservice.a(dso-dlfcn.o): In function `dso_error':
    /usr/local/src/daemon-1.0.1/src/native/unix/native/dso-dlfcn.c:52: undefined reference to `dlerror'
    collect2: error: ld returned 1 exit status
    make[1]: *** [jsvc] Error 1
    make[1]: Leaving directory `/usr/local/src/daemon-1.0.1/src/native/unix/native'
    make: *** [native/all] Error 2

    I double checked that the Ubuntu packages that provide those libs were installed (libc6 and libc6-dev).

    It turns out that, for some reason, under this distro that the GCC linker requires the -ldl argument to be listed last.  So that the invocation of:

    gcc -ldl -lpthread jsvc-unix.o libservice.a -o ../jsvc

    needs to be:

    gcc jsvc-unix.o libservice.a -o ../jsvc -lpthread -ldl

    To make this happen, do the following:

    Edit configure:

    For your $host_os update:

    LDFLAGS="$LDFLAGS -ldl -lpthread"


    LDFLAGS="$LDFLAGS -lpthread -ldl"

    Run # ./configure

    Then edit the ./native/Makefile:

    jsvc: jsvc-unix.o libservice.a
            $(LDCMD) $(LDFLAGS) jsvc-unix.o libservice.a -o ../jsvc


    jsvc: jsvc-unix.o libservice.a
            $(LDCMD) jsvc-unix.o libservice.a -o ../jsvc $(LDFLAGS)

    # make

    It should compile without any complaints

  • Configuring the Number of Workspaces on Ubuntu 12.10
    03/28/2013 11:40AM

    I typically like to have more than 4 workspaces for my X Windows sessions.

    Under Ubuntu 12.10 there is a little trickey involved in updating the default configuration.

    First you need to install the compizconfig-settings-manager.  This will enable you to configure the workspace switcher and some other system configs.  Be careful, this will also allow you to break things so only configure what you understand via compizconfig-settings-manager.

    Install ccsm:

    • # apt-get install compizconfig-settings-manager

    To run invoke (as root):

    • # ccsm

    To configure Workspace Switcher:

    • Go to 'General Options'
    • Click on 'Desktop Size' tab
    • Edit the 'Horizontal Virtual Size' and 'Vertical Virtual Size' to add additional workspaces


    Click the 'Back' and then the 'Close' button

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