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Thread: Help : Unable to authenticate su

  1. #1
    Join Date
    Jul 2008
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    Sydney, Australia
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    89
    Distro
    Ubuntu 8.04 Hardy Heron

    Help : Unable to authenticate su

    Hi. Today I have been unable to authenticate su. The message is -

    su: Authentication failure

    I am able to get into synaptic using my super password which is the same for su. Entering sudo -i gives me the following message -

    sudo: unable to resolve host ubuntu-server

    I am able to get into my home LAN & internet, so it is not networking related.

    What am I missing ? Please help.

    Thanks

  2. #2
    Join Date
    Mar 2008
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    City of Pines
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    Re: Help : Unable to authenticate su

    Quote Originally Posted by Dreamerman View Post
    Hi. Today I have been unable to authenticate su. The message is -

    su: Authentication failure

    I am able to get into synaptic using my super password which is the same for su. Entering sudo -i gives me the following message -

    sudo: unable to resolve host ubuntu-server

    I am able to get into my home LAN & internet, so it is not networking related.

    What am I missing ? Please help.

    Thanks
    Try to post whatever outputs when you issue the command below on your terminal:

    Code:
    cat /etc/hosts
    Steady movement is more important than speed, much of the time. So long as there is a regular progression of Stimuli to get your mental hooks into, there is room for lateral movement. Once this begins, its rate is a matter of discretion.

  3. #3
    Join Date
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    Re: Help : Unable to authenticate su

    Sometimes those type of errors are simply do to the host name for your computer being slightly different in /etc/hosts/ and /etc/hostname. Make sure those two files agree exactly about your host name.

  4. #4
    Join Date
    Jul 2008
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    Sydney, Australia
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    Distro
    Ubuntu 8.04 Hardy Heron

    Re: Help : Unable to authenticate su

    Quote Originally Posted by iaculallad View Post
    Try to post whatever outputs when you issue the command below on your terminal:

    Code:
    cat /etc/hosts
    Hi. The result as follows:-

    cat /etc/hosts
    127.0.0.1 localhost
    127.0.1.1 ubuntu-server.TOMKO

    # The following lines are desirable for IPv6 capable hosts
    ::1 ip6-localhost ip6-loopback
    fe00::0 ip6-localnet
    ff00::0 ip6-mcastprefix
    ff02::1 ip6-allnodes
    ff02::2 ip6-allrouters
    ff02::3 ip6-allhosts

    I have disabled IPv6 previously following instruction from the forum as follows:-

    1. sudo gedit /etc/modprobe.d/aliases (or your preferred text editor)
    2. Find the line: alias net-pf-10 ipv6
    3. Edit this to: alias net-pf-10 off
    4. Save the file and reboot

    Is my problem due to the above ?

    Thanks

  5. #5
    Join Date
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    Re: Help : Unable to authenticate su

    Do include the terminal prompt when you issue the cat /etc/hosts command.

    i.e:

    ian@gutsy-gibbon:~$ cat /etc/hosts
    cat /etc/hosts
    127.0.0.1 localhost
    127.0.1.1 gutsy-gibbon

    # The following lines are desirable for IPv6 capable hosts
    ::1 ip6-localhost ip6-loopback
    fe00::0 ip6-localnet
    ff00::0 ip6-mcastprefix
    ff02::1 ip6-allnodes
    ff02::2 ip6-allrouters
    ff02::3 ip6-allhosts
    Steady movement is more important than speed, much of the time. So long as there is a regular progression of Stimuli to get your mental hooks into, there is room for lateral movement. Once this begins, its rate is a matter of discretion.

  6. #6
    Join Date
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    Location
    Sydney, Australia
    Beans
    89
    Distro
    Ubuntu 8.04 Hardy Heron

    Re: Help : Unable to authenticate su

    Quote Originally Posted by iaculallad View Post
    Do include the terminal prompt when you issue the cat /etc/hosts command.

    i.e:
    OK. Here goes. Any obvious flaws ?-

    master@ubuntu-server:~$ cat /etc/hosts
    127.0.0.1 localhost
    127.0.1.1 ubuntu-server.TOMKO

    # The following lines are desirable for IPv6 capable hosts
    ::1 ip6-localhost ip6-loopback
    fe00::0 ip6-localnet
    ff00::0 ip6-mcastprefix
    ff02::1 ip6-allnodes
    ff02::2 ip6-allrouters
    ff02::3 ip6-allhosts
    master@ubuntu-server:~$
    master@ubuntu-server:~$

  7. #7
    Join Date
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    Re: Help : Unable to authenticate su

    Quote Originally Posted by Dreamerman View Post
    OK. Here goes. Any obvious flaws ?-

    master@ubuntu-server:~$ cat /etc/hosts
    127.0.0.1 localhost
    127.0.1.1 ubuntu-server.TOMKO

    # The following lines are desirable for IPv6 capable hosts
    ::1 ip6-localhost ip6-loopback
    fe00::0 ip6-localnet
    ff00::0 ip6-mcastprefix
    ff02::1 ip6-allnodes
    ff02::2 ip6-allrouters
    ff02::3 ip6-allhosts
    master@ubuntu-server:~$
    master@ubuntu-server:~$
    Yap, it seems that you're /etc/hosts file has the flaw. Edit and change the value.

    Code:
    gksudo gedit /etc/hosts
    and change the line of text:

    127.0.1.1 ubuntu-server.TOMKO
    With

    127.0.1.1 ubuntu-server
    Save and Close the file and test your su.
    Steady movement is more important than speed, much of the time. So long as there is a regular progression of Stimuli to get your mental hooks into, there is room for lateral movement. Once this begins, its rate is a matter of discretion.

  8. #8
    Join Date
    Jul 2008
    Location
    Sydney, Australia
    Beans
    89
    Distro
    Ubuntu 8.04 Hardy Heron

    Re: Help : Unable to authenticate su

    thanks. do i need to reboot ?

  9. #9
    Join Date
    Mar 2008
    Location
    City of Pines
    Beans
    3,585

    Re: Help : Unable to authenticate su

    Quote Originally Posted by Dreamerman View Post
    thanks. do i need to reboot ?
    No, that's a windoze thing. Just log-off and log back in
    Steady movement is more important than speed, much of the time. So long as there is a regular progression of Stimuli to get your mental hooks into, there is room for lateral movement. Once this begins, its rate is a matter of discretion.

  10. #10
    Join Date
    Jul 2008
    Location
    Sydney, Australia
    Beans
    89
    Distro
    Ubuntu 8.04 Hardy Heron

    Re: Help : Unable to authenticate su

    thx a lot. will do that & post result. BTW, your kid is very cute

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