a command line packet analyzer

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4
votes
1answer
342 views

How to investigate a random reset on TCP client port connected via loopback interface to a server

I have a test suite which initializes a server on the localhost and then runs thousands of stress tests which include starting and stopping clients connecting to this local server on same machine. I ...
3
votes
1answer
138 views

Using tcpdump to log blacklisted IPs

I am using tcpdump to log traffic outbound on a network. I would like to be able to log traffic on a host or IP-only basis but then I would like to be able to log large numbers of potentially ...
1
vote
1answer
201 views

Got the “ERROR: Cannot decode data link type 239” message when turn on sniffer mode

I would like install snort 2.9.6 into Centos 7 the installation is ok and the result of the self-testing mode is correct but when I run this command to change Snort into sniffer or nids mode. I got ...
1
vote
1answer
41 views

Network issue - only one machine can't access webpage on another machine

I'm trying to figure out why my MacBook is unable to reach the web page served by my Raspberry Pi while other computers on my local network (or on external networks) have no problems seeing the web ...
0
votes
1answer
15 views

tcpdump Filter with certain file types?

I use the unix command tcpdump with these extensions -A -s0 -ien0 port 80 I know how to add, for example a new host, that would be and \ host random.com Can I sniff for certain filetypes? I have ...
-1
votes
1answer
209 views

tcpdump host filter doesn't work

I'm using tcpdump on a linux ARM computer (Raspberry Pi). The command tcpdump host "ip" -v gives nothing when I go on the website "ip" with my laptop, but if I try tcpdump port 80 -v it works ...
2
votes
0answers
782 views

Creating multicast join for tcpdump captures

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 ...
2
votes
0answers
2k views

Dumping multicast UDP stream with socat

I am setting up video streaming. In local network, there are two devices streaming video over UDP multicast. One is regular computer with Linux (streaming to 239.220.221.10, port 9200), second one is ...
2
votes
0answers
97 views

tcpdump hello server certificate

On a device located between my local network and a router, (all the traffic pass through) I need to read the common name from Hello Server Certificate packet. So I'm trying to figure out how to get ...
2
votes
0answers
185 views

router latency measured by tcpdump increases

I am using tcpdump to measure latency on a linux router, i.e. the delay experienced by packets as they pass through the router (made of Ubuntu 10). For this purpose, I captured packets in the IN and ...
1
vote
0answers
24 views

record contents of packets dropped in iptables

I'm trying to find a way to record the entire contents of packets (possibly with tcpdump) that have been dropped according to rules in iptables. At present, I have a rule to log these packets (with a ...
1
vote
0answers
76 views

TCPDump To Capture A Tracepath6 Datagram

I'm trying to use TCPDump to capture an IPv6 datagram using: tcpdump -c 1 -i eth1 -vvvs0 ip6 and dst host H2.net2 & tracepath6 H2.net2 I'm running this script on H1.net1; R12.net1 is the ...
1
vote
0answers
33 views

I have a firewall bridge in pfSense and I want to log only the allowed packet

I have a bridge0 which has members em0 (wan) and vge0 (lan) I connect via ssh on vge0, when I tcpdump -i pflog0 I get the blocked packets from the bridge0, but when I tcpdump -i bridge0 I get both ...
1
vote
0answers
246 views

tcpdump not capturing http or tcp/ssl traffic

I have been trying to learn tcpdump and I am using this command to attempt to monitor my network: sudo tcpdump -I -i en1 But this gives me a bunch of stuff I don't want, so I used this version to ...
1
vote
0answers
65 views

Is it possible to view unicode text in tcpdump capture output?

Unfortunately seems like tcpdump is not capable of detecting and displaying Unicode-encoded text (specifically utf-8) in captures. It treats unicode text like regular binary data and displays it in ...
1
vote
0answers
506 views

Packets not received by TUN device

I created a TUN device(nat64) and created a route so that all the required packets are forwarded to the TUN device from an eth device. But, I see that many packets are not received by the TUN device. ...
0
votes
0answers
23 views

Sendmail - I/O error “Premature EOM” in maillogs

We're using sendmail as an MTA to send confirmation emails to customers that place orders on another server running IIS. Occasionally we see lines like this in the logs: SYSERR(root): collect: I/O ...
0
votes
0answers
28 views

Unable to capture trace with -w option

I am not able to capture trace with the -w option on my fedora machine. Please see the log below : [root@localhost home]# tcpdump -w /home/trace.cap -i eth2 -s 0 tcpdump: listening on eth2, link-type ...
0
votes
0answers
30 views

Get the information of each (single) flowing packet

tcpdump buffers data up to the default buffer size and then dumps it into disk. But let's say I need to get the information of the current flowing packet (a single packet), i.e. I don't want to wait ...