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KB45011 - How to collect a tcpdump on vTM.

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Last Modified Date2/10/2022 9:59 AM
Synopsis
At times, for troubleshooting purposes we may need to collect a tcpdump to look into the communication between the nodes. This is helpful in scenarios where User is facing latency or HA Communication is fluctuating or Health Monitors are failing etc.
This KB provides the steps for collecting the tcpdump and copying the file out of the vTM.
Problem or Goal
Cause
Solution
1. Log into the vTM CLI
2. Navigate to /logs location
3. Run the following command (For extremely busy environments you may want to tweak the command using examples below to collect limited info)

#Collects unfiltered captures. Try to keep the capture time to ~ 1 min.
tcpdump -i any -w Test.pcap
or
tcpdump -i any \(host 192.168.1.1 and host 192.168.1.2\) and tcp port 443 -w Test.pcap

4. Ctrl+C to stop the captures.
5. This capture will be saved in the /logs location (or the location where the command was executed. In this example its "/logs" )
6. If you want to take a quick look into the Output but do not want to save the file.

Example:
tcpdump -ni any \(host 192.168.1.1 and host 192.168.1.2\) and tcp port 443
-------------------------------------------------------------------------------------------------------------
Copying this file to Windows:
1. From Windows machine : You can use tools like Winscp or Filezilla and connect to the vTM and copy the file.
2. Fom Window CLI using below commands:

c:\> pscp.exe vtmadmin@vtm_ipaddress:/logs/Test.pcap C:\WindowsLocation\
(You'll be prompted for the vTM Password)

or

c:\> scp admin@10.209.70.128:/logs/errors \WindowsDirectory\


Copying this file from vTM to Linux:
scp /logs/Test.pcap adminuser@192.168.1.10/remotelocation
(You'll be prompted for the remote location 'adminuser' password)

 
Related Links
https://www.tcpdump.org/
Attachment 1 
Created ByCarlos Juan

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