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UDP coming in firewall?

Posted on 2012-12-28
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Last Modified: 2013-01-04
It appears UDP packets are coming from the Internet through the Firewall to specific servers.  

Anyone have any idea how this might have happened?  The firewall solution was IPtables.

Any thoughts would be appreciated.
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Question by:NYGiantsFan
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6 Comments
 
LVL 15

Assisted Solution

by:Frabble
Frabble earned 134 total points
ID: 38728424
It would help if you gave the source and destination ports. They could be return traffic for connections initiated by the servers. You should also be aware that Unix systems use UDP ports 33434 to 33534 for traceroute so are you allowing these in from the outside?
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Author Comment

by:NYGiantsFan
ID: 38728975
I will get those ports shortly. The firewall has NAT. The Destination IP was a private IP address.  (10.16.0.15)
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Author Comment

by:NYGiantsFan
ID: 38729036
Hi,
The source IP address port was 25033 and the destination IP address is 2877.
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LVL 57

Assisted Solution

by:giltjr
giltjr earned 166 total points
ID: 38732522
Is the traffic coming into your firewall with the destination IP address of 10.16.0.15, or is this what the public IP address is NAT'ed to?

If 10.16.0.15 is what the NAT translates to, is that IP address valid on your network?

Does is have a service/task listening on UDP port 2877?
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LVL 12

Accepted Solution

by:
DarinTCH earned 200 total points
ID: 38733922
UDP traffic is a legitimate type of traffic for many protocols

so unless we know what your allowing and blocking
protocol wise
its hard to say

was the traffic originated from outside or did your system generate something and your only looking at the return session???

IPTables is a very sinple FW at best

it can be tweaked and used to control traffic to a degree but IT IS NOT a legitimate Enterprise solution

that's why there are several Networking/security companys making the big bucks selling FW
even a open source FW would provide more than IPTables
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Author Closing Comment

by:NYGiantsFan
ID: 38744746
My question was rather vague.  I will refine the question.  Thank you everyone for your thoughts.
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