Network Issues and how to troubleshoot them

Network Issue and how to Solve them

 

Tcp Dump

Is a very powerfull tool when looking into network related issues.

 

# Check If a port is sending data or receiving data
tcpdump -vvv port 10005

# Check if you are receiving anything from a ipaddress
tcpdump -n host 10.10.32.118

# Check if you are reciving anything from a port at an ipadress
tcpdump -vvv -n 10.10.32.22 port 10006

# Specify if its a Source or Destination
tcpdump -vvv -n host 10.10.32.118 and src port 3456
tcpdump -vvv -n src host 10.10.32.22 and port 10006

 

Get the actual packet Content

# Get the packet content with tcpdump
tcpdump -nnvvXSs 1514

 

Netcat

# Use netcat like this
nc -s 10.10.32.118 -p 21

 

# Save the packets to a file
tcpdump -vvv -i eth0 host 10.10.32.118 -s0 -w /tmp/hello.cap

# Show the packet header with the HEX
tcpdump -vvv -i eth0 host 10.10.32.118 -s0 -X

# Show the raw packet directly in the console
tcpdump -vvv -i eth0 host 10.10.32.118 -s0 -A

 

 

Posted on: Wednesday 13 January 2016