Year: 2013

About twice a week, I get a call that a Dymo LabelWriter 450 no longer works. In most cases, the reason was that the user pulled the USB cable.

My Dymo LabelWriters are connected to a Dymo printserver. While the printservers can be monitored using ping, this does not allow you to see if the printer it still connected to the printserver. Luckily the Dymo printserver has SNMP support with the option to see what device is connected.

I did a SNMPWalk against the printserver, first with the LabelWriter connected, then disconnected. Aside from some counters, three values were different:

I also found that HOST-RESOURCES-MIB::hrDeviceDescr.2 sometimes shows the correct printer string one time, but doesn't show it the second time:

$ snmpget -v 1 -c public dymo2  HOST-RESOURCES-MIB::hrDeviceDescr.2
HOST-RESOURCES-MIB::hrDeviceDescr.2 = STRING: DYMO LabelWriter 450
$ snmpget -v 1 -c public dymo2  HOST-RESOURCES-MIB::hrDeviceDescr.2
HOST-RESOURCES-MIB::hrDeviceDescr.2 = STRING: 
$ snmpget -v 1 -c public dymo2  HOST-RESOURCES-MIB::hrDeviceDescr.2
HOST-RESOURCES-MIB::hrDeviceDescr.2 = STRING: DYMO LabelWriter 450
$ snmpget -v 1 -c public dymo2  HOST-RESOURCES-MIB::hrDeviceDescr.2
HOST-RESOURCES-MIB::hrDeviceDescr.2 = STRING: 
$ snmpget -v 1 -c public dymo2  HOST-RESOURCES-MIB::hrDeviceDescr.2
HOST-RESOURCES-MIB::hrDeviceDescr.2 = STRING: DYMO LabelWriter 450

Therefore, I use a script that tries 10 times in a row. If it finds a valid string at least once, that's good enough:

#!/bin/bash
 
[ "$1" == "" ] && { echo "Syntax: $0 [hostname]" ; exit 1; }
 
i=0
while [ $i -lt 10 ]; do
        response=$(/usr/lib64/nagios/plugins/check_snmp -H $1 -o HOST-RESOURCES-MIB::hrDeviceDescr.2 -R dymo)
        retval=$?
        if [ $retval -eq 0 ]; then
                echo $response
                exit $retval
        fi
        i=$((i+1))
done
 
echo "Printer disconnected from printserver"
exit 2

This script can be used with Nagios to monitor the LabelWriter.

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I've got an image of a USB disk that was created with the command dd. How can we mount it and access files? The file is named smosimg

Method 1: fdisk and bash

# fdisk -l smosimg
 
Disk smosimg: 1993 MB, 1993342976 bytes, 3893248 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000336e0
 
  Device Boot      Start         End      Blocks   Id  System
smosimg1   *        2048     1230847      614400   83  Linux
smosimg2         1230848     3893247     1331200   83  Linux

I want to mount the second partition that starts at block 1230848. The block size is 512 bytes, so we multiply 1230848 by 512:

mkdir target
mount -o loop,offset=$((1230848*512)) smosimg target

Method 2: kpartx

mkdir target
kpartx -a smosimg
mount /dev/mapper/loop0p2 target -o loop
kpartx -d smosimg

Method 3: losetup

mkdir target
losetup --partscan --find --show disk.img
mount /dev/loop0p2 target
losetup -d /dev/loop0

I've personally tested all three methods, and on my Fedora 18 machine, they all work.

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One of the computers I manage had a problemen with Windows Photo Viewer, which crashed with the message "COM Surrogate has stopped working".

Especially when clicking "Next" in the viewer, the application crashed.

It's a 64 bit Dell computer running Windows 7 with all updates applied. It has a Trend Micro virusscanner and a TightVNC 2.x server for remote management.

What is COM Surrogate?

Often, COM objects are defined in DLLSs, a piece of code that is executable, but just not by itself. It is started by another program when needed. But sometimes, you just want to run code from a DLL without writing a complete wrapper program around it. That's where Microsoft has provided a program that can execute parts of a COM DLL without developing a complete program to load the DLL.

This program is called dllhost.exe and has user friendly name "COM Surrogate

What can I do against a crashing COM Surrogate?

I read several solutions, most of which were useless to me, but they may help you.

Replace video card

In my case, the issue was that the drivers of the onboard video card crashed. The computer is an Optiplex 9010 with an Intel® Q77 Express Chipset (Intel® BD82Q77 PCH) chipset that has Integrated Graphics.

I inserted an ATI Radio HD34xx card, which was automatically installed by Windows 7. After a reboot, the problem seems to be completely gone.

Commands

There are a few dlls that can be "re-registered" with Windows. Click on start, type cmd and right-click to choose "Run as Administrator". On the command line, type:

regsvr32 vbscript.dll
regsvr32 jscript.dll

Check Disk for Errors

Bad sectors on the hard drive could be the cause of COM Surrogate crashing. You can check your disk with the chkdsk command.

Disable DEP for dllhost.exe

Another fix that is suggested by numerous websites, is adding dllhost.exe to the exception list of DEP (Data Execution Prevention).

On 32-bit systems, you could whitelist:

C:\Windows\System32\dllhost.exe

C:\Windows\SysWOW64\dllhost.exe

If it were your financial software, I would not advice against it, but dllhost.exe is used by so many programs, that I don't consider it safe to exclude.

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