Useful TCPDUMP commands
Contents
Useful TCPDUMP commands for debugging
I have only found a few times that I needed to use tcpdump, most of them are for firewall issues.
Basic TCPDUMP commands
Checking to see what interfaces we can use with tcpdump
tcpdump -D
Listen to all traffic coming in over a specific interfacae
tcpdump -i eth0
*note the -i stands for interface
Listen to all traffic on all interfaces
tcpdump -i any
At this point you will notice there is alot of information going to and from your computer.
There are 4 settings when it comes to verbose information(verbose, more verbose, very verbose, less verbose)
Verbose
tcpdump -v
More Verbose
tcpdump -vv
Oddly enough Very verbose
tcpdump -vvv
Less verbose mean less then the default
tcpdump -q
Say you want to dispaly ipaddress and ports vers domains and service ports
tcpdump -n
More fun tcpdump combinations
Capture all bytes of data within the packet:
tcpdump -s 0
Capture 500 bytes of data for each packet rather than the default of 68 bytes:
tcpdump -s 500
Capture any packets where the destination host is 192.168.1.1. Display IP addresses and port numbers:
tcpdump -n dst host 192.168.1.1
Capture any packets where the source host is 192.168.1.1. Display IP addresses and port numbers:
tcpdump -n src host 192.168.1.1
Capture any packets where the source or destination host is 192.168.1.1. Display IP addresses and port numbers:
tcpdump -n host 192.168.1.1
Capture any packets where the destination network is 192.168.1.0/24. Display IP addresses and port numbers:
tcpdump -n dst net 192.168.1.0/24
Capture any packets where the source network is 192.168.1.0/24. Display IP addresses and port numbers:
tcpdump -n src net 192.168.1.0/24
Capture any packets where the source or destination network is 192.168.1.0/24. Display IP addresses and port numbers:
tcpdump -n net 192.168.1.0/24
Capture any packets where the destination port is 23. Display IP addresses and port numbers:
tcpdump -n dst port 23
Capture any packets where the destination port is is between 1 and 1023 inclusive. Display IP addresses and port numbers:
tcpdump -n dst portrange 1-1023
Capture only TCP packets where the destination port is is between 1 and 1023 inclusive. Display IP addresses and port numbers:
tcpdump -n tcp dst portrange 1-1023
Capture only UDP packets where the destination port is is between 1 and 1023 inclusive. Display IP addresses and port numbers:
tcpdump -n udp dst portrange 1-1023
Capture any packets with destination IP 192.168.1.1 and destination port 23. Display IP addresses and port numbers:
tcpdump -n "dst host 192.168.1.1 and dst port 23"
Capture any packets with destination IP 192.168.1.1 and destination port 80 or 443. Display IP addresses and port numbers:
tcpdump -n "dst host 192.168.1.1 and (dst port 80 or dst port 443)"
Capture any ICMP packets:
tcpdump -v icmp
Capture any ARP packets:
tcpdump -v arp
Capture either ICMP or ARP packets:
tcpdump -v "icmp or arp"
Capture any packets that are broadcast or multicast:
tcpdump -n "broadcast or multicast"
Check to see if a specific client is connecting to MySQL over port 3306
tcpdump -i any -s 0 -l -w - dest port 3306 and src host 192.168.1.1
