/etc/init.d/ntop fails to detect missing network interface

[Ralph Corderoy]

Binary package hint: ntop

Ubuntu 8.04, ntop 3:3.2-10.1.

/etc/init.d/ntop has check_interfaces() which includes

    { echo $INTERFACES | awk -F , '{ for(i=1;i<=NF;i++) print $i }' |
    while read iface ; do
        if ! ifconfig "$iface" | grep -w UP >/dev/null; then
            echo "ERR: interface $iface is DOWN..."
            return 1
        fi
    done
    return 0
    }
    return $?

It's called thus.

    echo -n "Starting $DESC: "
    if ! sanity_check || ! check_log_dir || ! check_interfaces; then
        echo " will not start $DESC!"
        exit 1
    fi
    start-stop-daemon --start ...

Running the script with `bash -x' shows it isn't working as intended.

    + ifconfig eth0
    + grep -w UP
    eth0: error fetching interface information: Device not found
    + echo 'ERR: interface eth0 is DOWN...'
    ERR: interface eth0 is DOWN...
    + return 1
    + return 0
    + start-stop-daemon --start --quiet --name ntop --exec /usr/sbin/ntop -- -d -L -u ntop -P /var/lib/ntop --skip-version-check -a /var/log/ntop/access.log -i eth0 -p /etc/ntop/protocol.list -O /var/log/ntop

There's a `return 1' followed by a `return 0' so the error is getting
cleared with the result that the start-stop-daemon gets to try and start
the ill-configured daemon. It's probably due to using return inside an
if-statement inside a while-statement and bash subshells.

[alej0 (alej0varas)]

    "eth0: error fetching interface information: Device not found"

This error is from ifconfig not from ntop, the problem is that eth0 doesn't exist.

You can change the interface ntop works for in /var/lib/ntop/init.cfg

[Ralph Corderoy (ralph-inputplus)]

Hi alej0, I think you've misunderstood. I'm aware that the error comes
from ifconfig(8) and that ifconfig is correct in giving it. But
/etc/init.d/ntop then proceeds to start-stop-daemon anyway, even though
its code attempts to avoid this precisely because ifconfig didn't say
`UP'. The code isn't behaving as the author intended and that's the
bug. The output from `bash -x' I gave shows this.

[alej0 (alej0varas)]

Sorry for the misunderstood. Now I got it, here is a patch for /etc/init.d/ntop.

[Shirish Agarwal (shirishag75)]

alej0,
    It would be nice if you could/would forward the patch upstream as well (for consideration) .

I also ran into this bug and had to use your work-around. ntop should be intelligent to know which interfaces is actually up and doing stuff.

[Ludovico Cavedon (cavedon)]

The next upload of ntop will fix this issue.
Thank for reporting the issue.

[Ralph Corderoy (ralph-inputplus)]

Is there an easy way to see the fixed /etc/init.d/ntop or its source?

[Ludovico Cavedon (cavedon)]

On 01/25/2011 07:14 AM, Ralph Corderoy wrote:
> Is there an easy way to see the fixed /etc/init.d/ntop or its source?

Here:
http://git.debian.org/?p=collab-maint/ntop.git;a=blob;f=debian/ntop.init

[Launchpad Janitor (janitor)]

This bug was fixed in the package ntop - 3:4.0.3+dfsg1-2

---------------
ntop (3:4.0.3+dfsg1-2) unstable; urgency=low

  [ Ludovico Cavedon ]
  * Rename maintainer scripts including the package name.
  * Remove misplaced ru.po file.
  * Add Vcs-* headers.
  * Do not call netstat, but read interface list from /proc (Closes: #607637).
  * Use "set -e" in maintainer scripts (see lintian warning
    maintainer-script-without-set-e).
  * Fix bug in check_interfaces() config function.
  * ntop.default: avoid prerm failure if package has never been fully
    configured.
  * Prevent config script failure if password is not asked (Closes: #607580).
  * Cleanup postrm script, thanks to J.M.Roth (Closes: #568626):
    - do not delete user (might be shared)
    - no need to remove /etc/ntop
    - wrap db_purge in a debconf availability check
    - re-indent
  * Add hostname-in-man-description.patch by A. Costa in order to add
    hostname:port in the description section of the man page
    (Closes: #466506).
  * Remove init.cfg from source package, as it is generated by postinst.
  * Handle interface "none", merged patch from Jason Healy (Closes: #520319).
  * Add dependency on net-tools, needed by the init script.
  * Make sure /var/log/ntop is not world readable and set group to adm. Thanks
    to J.M.Roth (Closes: #568641).
  * Set random password admin password if no password have ever been set
    and it is not possible to ask the user (LP: #355127).
  * Suggest geoip-database-contrib and add symlinks to its files.
    Explained in README.Debian.
  * Fix permissions in /var/lib/ntop (LP: #138682). Set sticky bit on
    /var/lib/ntop, so ntop user cannot change init.cfg, but can create
    subdirectories.
  * Disable DNS resolution as it makes ntop unstable.
  * Fix detection of not-active interfaces in ntop.init (LP: #231024).
  * Update po files.

  [ Jordan Metzmeier ]
  * Set password in postinst instead of config (Closes: #609070)
  * Add prompt to reset password if it is already set.
  * Update debconf template thanks to reviews by Christian Perrier and
    Justin B Rye.

  [ Daniel Baumann ]
  * Correct chown calls in ntop.postinst to not fail upon initial installation
    when the respective files are not yet present on the system.
 -- Ludovico Cavedon <email address hidden> Tue, 25 Jan 2011 23:39:56 -0800