How to find specific port traffic in tcpdump?
You can find specific port traffic by using the port option followed by the port number. -nn : Don’t resolve hostnames or port names. -S : Get the entire packet.
Which is DNS record type does tcpdump support?
If you pass -v -v to tcpdump, you can get a little bit more information and you may find that our DNS server also adds an additional OPT pseudo-DNS record type, used to support EDNS . In particular, bind (8) uses an EDNS option code 65001 to send and process so-called “Source Identity Tokens”, or DNS Cookies, which explains the larger query size.
Where can I find tcpdump in Debian?
For debian it can be installed directly from the debian repository: TCPdump allows write a sniff to file or display it realtime. It provides several ways how to use it for DNS analysis.
How to break down the tcpdump command line?
Breaking down the Tcpdump Command Line The following command uses common parameters often seen when wielding the tcpdump scalpel. :~$ sudo tcpdump -i eth0 -nn -s0 -v port 80 -i : Select interface that the capture is to take place on, this will often be an ethernet card or wireless adapter but could also be a vlan or something more unusual.
What are the different types of expressions in tcpdump?
Mastering the expressions and learning to combine them creatively is what makes one truly powerful with tcpdump. There are three main types of expression: type, dir, and proto. Type options are: host, net, and port. Direction lets you do src, dst, and combinations thereof.
What does the VLAN keyword mean in tcpdump?
Tcpdump has an unintuitive interface when filtering for VLAN tags. The critical piece of information to understand is that the position of the word ‘vlan’ in the tcpdump filter is paramount when it comes to tcpdump filter compilation. The ‘vlan’ keyword in a tcpdump filter changes the lookup offsets for all other keywords following the keyword.