UDP & security

  • Thread starter Thread starter J. Clarke
  • Start date Start date
J

J. Clarke

All -

I have an app on W2K that recieves a UDP on a specific port. With the
exception of 1 user it works great (for the rest of the users). The one
user gets an error message about unable to bind to the port. I am starting
to recieve reports of this happening in the field with out application.

I am thinking this is privledge related to the users profile. Darned if I
know what it could be. If anyone has any thoughts please point me in a
direction to help resolve it....

Regards,
Jeff
 
that could be because some other program is listening on the same port.
possibly a second instance of your app running?? try checking out
netstat -a and see if anything is already listening on that port.
 
Make sure that no firewall [software or hardware], protection application, or port
filtering is interfering. Software firewalls and other startup apps can be bypassed
by booting into safe mode with networking which could put a computer at risk however
if that is all that is protecting them from the internet. Software firewalls in
particular offer many possibilities to block legitimate traffic, but can be
configured to allow it. If you suspect a permissions issue, temporarily add the user
to the local administrators group to see if the problem goes away or not. Using a
packet sniffer like the free Ethereal can help trouble shoot network applications by
watching the packet sequence, though it would be more helpful to also compare results
to working computer. Also look in the Event Viewer of the problem computer for any
pertinent error massages. --- Steve
 
Thanks Steve/Dave - For sure there is only one instance of the app running,
with no others running. A personal firewall is not running on this macine
either. Would a hardware firewall prevent UDP messages from flowing on an
internal network? I'm not in the office now so I can't try the netstat -a
command (yet). I appreciate the suggestions.

Jeff

Steven L Umbach said:
Make sure that no firewall [software or hardware], protection application, or port
filtering is interfering. Software firewalls and other startup apps can be bypassed
by booting into safe mode with networking which could put a computer at risk however
if that is all that is protecting them from the internet. Software firewalls in
particular offer many possibilities to block legitimate traffic, but can be
configured to allow it. If you suspect a permissions issue, temporarily add the user
to the local administrators group to see if the problem goes away or not. Using a
packet sniffer like the free Ethereal can help trouble shoot network applications by
watching the packet sequence, though it would be more helpful to also compare results
to working computer. Also look in the Event Viewer of the problem computer for any
pertinent error massages. --- Steve


J. Clarke said:
All -

I have an app on W2K that recieves a UDP on a specific port. With the
exception of 1 user it works great (for the rest of the users). The one
user gets an error message about unable to bind to the port. I am starting
to recieve reports of this happening in the field with out application.

I am thinking this is privledge related to the users profile. Darned if I
know what it could be. If anyone has any thoughts please point me in a
direction to help resolve it....

Regards,
Jeff
Click to expand...
Click to expand...
 
A perimeter hardware firewall would not interfere with lan traffic on the same
subnet. It still would be a good idea to try booting into safe mode with networking
as part of the troubleshooting process. --- Steve

J. Clarke said:
Thanks Steve/Dave - For sure there is only one instance of the app running,
with no others running. A personal firewall is not running on this macine
either. Would a hardware firewall prevent UDP messages from flowing on an
internal network? I'm not in the office now so I can't try the netstat -a
command (yet). I appreciate the suggestions.

Jeff

Steven L Umbach said:
Make sure that no firewall [software or hardware], protection application, or port
filtering is interfering. Software firewalls and other startup apps can be bypassed
by booting into safe mode with networking which could put a computer at risk however
if that is all that is protecting them from the internet. Software firewalls in
particular offer many possibilities to block legitimate traffic, but can be
configured to allow it. If you suspect a permissions issue, temporarily add the user
to the local administrators group to see if the problem goes away or not. Using a
packet sniffer like the free Ethereal can help trouble shoot network applications by
watching the packet sequence, though it would be more helpful to also compare results
to working computer. Also look in the Event Viewer of the problem computer for any
pertinent error massages. --- Steve


J. Clarke said:
All -

I have an app on W2K that recieves a UDP on a specific port. With the
exception of 1 user it works great (for the rest of the users). The one
user gets an error message about unable to bind to the port. I am starting
to recieve reports of this happening in the field with out application.

I am thinking this is privledge related to the users profile. Darned if I
know what it could be. If anyone has any thoughts please point me in a
direction to help resolve it....

Regards,
Jeff
Click to expand...
Click to expand...
Click to expand...
 
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