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DC Fails to Back Up Device Data Because the Firewall Disables Port 10000

Publication Date:  2012-07-25 Views:  52 Downloads:  0
Issue Description
A customer uses the DC backup tool to back up data of the UA5000 and finds that the backup progress bar remains at 0% all the time. Some time later, a message is displayed indicating that the file transmission fails.
The networking is as follows:
N2000 BMS server � E500 firewall � customer’s DCN network � UA5000.
IP address of the server: **.**7.96.227
IP address of the UA5000: **.**7.116.1
IP address of the N2000 BMS client: **.**7.4.1
Solaris + Sybase 
Alarm Information
Handling Process
1. Check the configuration of the DC on the server and find that the configuration is correct.
2. The N2000 BMS can receive device alarms. Hence, port 162 is not disabled.
3. Check the configuration of the firewall and find that port 69 is enabled.
4. Check the TFTP service of the N2000 BMS server. No fault is detected.
root@N2000DBServer # netstat -a|grep tftp
*.tftp Idle
*.tftp Idle
To further to verify the availability of the TFTP service, do as follows:
Create a b.txt file under the root directory of disk D on the client and enter Verify the availability of the TFTP service.
Telnet to the server, create a b.txt file under directory tftpboot, and assign read and write rights:
root@N2000Server # cd /tftpboot
root@N2000Server # touch b.txt
root@N2000Server # chmod 777 b.txt
Open the CMD window on the client, switch to the root directory of disk D, and run the following command:
D:\>tftp **.**7.96.227 put b.txt
Transfer successful: 14 bytes in 1 second, 14 bytes/s
Check the b.txt file of the server and find that the file is not blank:
root@N2000Server # more b.txt
Verify the availability of the TFTP service.
root@N2000Server #
5. Analyze the log information about the DC and capture packets.
Open the DC logs as follows:
In directory /opt/n2000/server/conf/dc.cfg, the following message is displayed:
#For debugging the data center
Change 0 to 1 and restart the DC daemon.
For logs, see the appendix DC Logs.rar.
Query the logs and find that the interactive process of the SNMP is normal. The progress is always displayed as 0.
As the TFTP process cannot be captured by using the snmpsniff software, use SNOOP that is provided by OS to capture packets:
snoop -o tftp.cap -xa -ta -v -d name of the network adapter -r **.**7.116.1
Use the ethreal to open the downloaded packets.
The SNMP packets are normal during interaction. Focus on the TFTP process.
The UA5000 initials a write request with the source port 10000 and target port 69.
The N2000 BMS responds the Acknowledgement packet with the random source port 42887 (from port 32768 to port 65535) and target port 10000.
Normally, the UA5000 initials data packets after receiving the Acknowledgement packet. But the UA5000 fails to perform this operation.
The possible causes are as follows:
The UA5000 fails to receive the Acknowledgement packet from the N2000 BMS. The Acknowledgement packet is discarded and port 10000 is disabled.
The UA5000 receives the Acknowledgement packet and responds data packets. But the data packets are discarded and port 42887 is disabled.
As the contents of the packets involve the IP address of the customer, the original packet cannot be uploaded. For the captured screen, see the appendix Fault Packet Analysis.rar.
Check whether the firewall has disabled port 10000 and ports 32768 to 65535.
It is found that port 10000 is disabled. After port 10000 is enabled, the problem is solved. 
Root Cause
1. The configuration of the DC system information on the server is incorrect.
2. The port number UDP162 between the N2000 BMS server and the UA5000 is disabled.
3. The port number UDP69 of the TFTP between the N2000 BMS server and the UA5000 is disabled.
4. The TFTP service is not started.
5. Analyze the fault by querying logs and capturing packets. 
When handling problems regarding the DC, understand the entire backup process first, and trace the problems rapidly by querying logs and capturing packets.