Nov 2, 2019 · I would use sudo tcpdump -i eth0 -s 0 -w tcpdump.pcap host hostA and udp to up the length to "a lot", write the data to a file and use host rather than src to capture the data in both directions. Essentially you are missing the word and between src and udp.

Apr 4, 2018 · The -s0 option is important too: it makes tcpdump grab the whole package and not just the protocol headers at the beginning of each package.

Use the switch- host in tcpdump I never used a saved pcap file with switches but hope it can work. How you use in live tcpdump Example- See traffic 'to and from' 10.2.1.50 tcpdump -nnA host 10.2.1.50 or to see results from a network tcpdump -nnA net 10.2.1.0/24 or to see traffic originating from 10.2.1.50 tcpdump -nnA src 10.2.1.50 Hope it helps

Apr 13, 2015 · When observing traffic with sudo tcpdump udp, it behaves like it should: I can see all traffic which is happening in the network, even when the machine which I am using is not involved. However, w...

Jul 29, 2021 · "Is there a easy way to determine the transport protocol of a packet by looking at the output of a TCP dump trace?" - this solely depends on the kind of protocol and on your experience. tcpdump itself does not offer some application layer protocol detection.

I want to write a linux shell script which will capture specific multicast traffic. Specific as in, I want to create a pcap file that has all the traffic for one specific multicast group/port. Here is the command line I am using to view traffic: tcpdump -nnXs 0 …

Seems that tcpdump is the best, if not the only answer here. It looks perfect for this job. Since, I'm using very limited version of Linux on my NAS, it wasn't there. But simple call to ipkg install tcpdump solved the problem (hopefully I've installed Optware before, as it was also missing). For this particular problem (listening for UDP packets on ports 3333 or 7777) command to execute …

Sep 9, 2024 · The same issue was discovered on several Linux systems in our environment with different patch levels, different versions of traceroute and no matter whether system is a VM or physical. To simplify and for easier reading of tcpdump, I tried with the following command: for i in {1..10}; do traceroute -s 10.1.3.205 -r 10.1.3.210 -n 1 -m 1 -q 1; done

So indeed, your UDP scanning to port 80/UDP simply receives an ICMP unreachable message back because there is not a service listening to that combination or protocol/port.

Mar 9, 2019 · I hope this sheds some light on the issue. From the manpage: When tcpdump finishes capturing packets, it will report counts of: packets captured (this is the number of packets that tcpdump has received and processed); packets received by filter (the meaning of this depends on the OS on which you're running tcpdump, and possibly on the way the OS was …