Udp Dst Port 0
Tcpdump -i lo udp port 8125 -vv -XTo briefly explain the options we passed to it:.i lo only captures packets on the local loopback i.e. Packets sent to localhost. udp means that only UDP packets will be captured. Other types of packets we might capture could be tcp or icmp for example.vv just gives us more verbose output.X prints out the data in the UDP packets in ASCII as well as hex. If we just wanted the latter we could use the -x optionThis is what one of the messages received by tcpdump looks like. 13:36 IP (tos 0x0, ttl 64, id 58103, offset 0, flags DF, proto UDP (17), length 37)localhost.48358 localhost.8125: bad udp cksum 7c8f!
What is the meaning of port 0 in netstat -an output in Windows? I'm asking about socket in Foreign address column: 0.0.0.0:0 I know that 0.0.0.0 address means, that host is listening on all inter.
Udp Dst Port 0 5
UDP, length 90x0000: 4500 0025 e2f7 4000 4011 59ce 7f00 0001 E.%.@.@.Y.0x0010: 7f00 0001 bce6 1fbd 0011 fe24 626c 6168.$blah0x0020: 3a33 367c 63:36 cThe last three lines of this output detail the IP header, UDP header and the data in the packet. The following diagram is quite useful for understanding what each part of the IP header is defining. Source:This diagram defines things in terms of bits whereas the tcpdump output is in hexidecimal. Each block of 4 hexidecimal digits is equivalent to 16 bits.There are a couple of parts of the IP header that might be interesting to us in this case.The first 4 bits/1 digit define the IP version which is 4 in this case since we’re using IPv4.The next 4 bits define the Internet Header length – the number of 32 bit words in the header.