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How can I capture incoming and outgoing packets on DX? (KB ID: KB8948)

Article ID: KB8948
Former Article ID:
Published: Dec 06, 2007
Last Modified: Dec 06, 2007
Visible By: Employee, PTAC, Partner, Customer, Public

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Article URL

http://kb.juniper.net/KB8948

Synopsis

Capturing packets is necessary at times in order to successfully diagnose certain specific problems.

Problem

I'd like to capture TCP packets to understand why my application is not functioning properly when going through the DX.

Solution

The following are the commands used to prepare the DX to capture the packets; along with the transports used when copying the file over.

Here are the commands on how to get the DX (Redline) setup for TCPdump.

set admin tcpdump transport [tftp/smtp/scp]      ..... TFTP is commonly used
set admin tcpdump filename <filename>
set admin tftp server <server name>
write

The command to start the packet capture is the following:

tcpdump                 .....(this command will start the tcpdump trace. Takes approximately 2 minutes)
copy tcpdump     .....(copy tcpdump to a remote destination)

To capture TCP packets to and from specific hosts from a particular cluster/forwarder as well as all the traffic to and from the target hosts, use the following example:

Cluster:    10.82.11.13:80
Target 1:  10.82.11.10:80
Target 2:  10.82.11.11:80

tcpdump -i ether0 (host 10.82.11.13 and port 80) or (host 10.82.11.10 and port 80) or (host 10.82.11.11 and port 80)

Category Description

By Product » Hardware » Application Acceleration
By Product » Software » Network Operating Systems » DXOS Software

Purpose

Troubleshooting

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