a command line packet analyzer

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4
votes
1answer
503 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 ...
4
votes
1answer
31 views

what is “rfc3442-classless-static-routes” in /etc/dhcp/dhclient.conf

I am trying to debug DHCP on my laptop (I am using dhcping and dhcdump to see what the DHCP server sends back). Following is my /etc/dhcp/dhclient.conf. option rfc3442-classless-static-routes code ...
1
vote
0answers
14 views

Count all network requests to a specific host

I have a mock server running on my localhost that mocks out a back end service that I need for my app. One thing that I want to do is count the number of requests [GET, POST, PUT, DELETE,...] that my ...
0
votes
1answer
34 views

put tcpdump in promiscuous mode and sniffing from any pc

At my home I use a wireless router to connect to internet, so every device uses wireless card to use it. In this way using sudo tcpdump -i wlan0 from my pc I should be able to see all the packets ...
10
votes
3answers
7k views

Why would the kernel drop packets?

I interrupted tcpdump with Ctrl+C and got this total summary: 579204 packets captured 579346 packets received by filter 142 packets dropped by kernel What are the "packets dropped by kernel"? Why ...
0
votes
1answer
29 views

tcpdump -i any and promiscuous mode

From the man page for tcpdump 4.1.1 (yes I know its old) -i Listen on interface. If unspecified, tcpdump searches the system interface list for the lowest numbered, configured ...
1
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0answers
21 views

Replay pcap on local machine only

RHEL 6.5. I have a capture of UDP packets, generated this way: tcpdump -nnXs 0 -i eth1 udp port 26477 and dst 233.86.230.111 -w ITCH.pcap I've moved this file over to a dev VM, and want to replay ...
0
votes
1answer
37 views

Smallest packet sniffer for an embedded device?

Are there tiny packet sniffers out there? I'm looking for something that can be compiled for a embedded device with very limited space. I thought of tcpdump but a dynamically linked and stripped ...
1
vote
1answer
54 views

one way file sync with unison or better alternative

I have been collecting a logs for user actions on the network using a program similar to tcpdumps; with every millisecond the file being written to. I am currently using unison to synchronize the logs ...
0
votes
1answer
27 views

tcpreplay output to STDOUT?

$ tcpreplay tcpdump-2015-01-02-18h-13m.pcap ERROR: The intf1 option is required tcpreplay (tcpreplay) - Replay network traffic stored in pcap files USAGE: tcpreplay [ -<flag> ...
0
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0answers
33 views

How to use tshark or tcpdump to calculate bytes transmitted

I am using this command with tshark: tshark -r pcapfile "tcp and ip.src==192.168.1.1" -T text -V -x | grep 'Total Length' This essentially parses the pcap for only connections from the source ip and ...
3
votes
2answers
3k views

Using tcpdump to extract NFS RPC contents

Fairly simple question... I'm running tcpdump and trying to analyze the contents of the TCP packets between server/client. I see the "GETATTR" RPC being received, which is great! However, I want to ...
1
vote
0answers
30 views

How can I log outgoing TCP traffic including the full path of URLs?

I use a program regularly on Linux that makes a TCP request when it starts up and updates a file with an access token before launching. I'd like to write a batch script that makes this request (using ...
0
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0answers
96 views

tcpdump - packets dropped by interface

The man for tcpdump states what can cause "packets dropped by kernel" but it doesn't state what can cause "packets dropped by interface". Can anyone shed some light as to why the interface may be ...
1
vote
1answer
170 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
1answer
60 views

how to capture and see packet contents with tcpdump

I am trying to HTTP traffic to port 8007 in a file and then view them later. # tcpdump -i eth0 -s0 -n -w /tmp/capture port 8007 & # tcpdump -r /tmp/capture -A | grep '10.2.1.50' I expected to ...
0
votes
1answer
19 views

Itcpdump output - why is it showing an Ethernet status?

tcpdump -i mlan0 -n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on mlan0, link-type EN10MB (Ethernet), capture size 262144 bytes Why is this ...
0
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0answers
66 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 ...
1
vote
1answer
108 views

tcpdump won't capture entire packet

I'm using sudo tcpdump -A -s0 -ien0 port 80 | grep schemas-microsoft >> ~/Downloads/convert.txt to capture microsoft-schema xmls being sent throught the internet, when tcpdump is supposed to ...
1
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0answers
115 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
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0answers
84 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
2answers
96 views

tcpdump doesn't appear to be capturing any data, why?

I'm trying to capture data with tcpdump like so: $ sudo tcpdump -Xi eth0 I have the device and the PC connected to each other. On both sides I launch a simple test application that sends a message ...
1
vote
1answer
124 views

tcpdump and nc with udp

I don't understand the behaviour of netcat. Let's say that I have one host acting as server: [root@localhost tmp]# nc -u -l -p 670 Then I try to connect from a client: root@debian:/tmp# nc -u ...
0
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0answers
32 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 ...
1
vote
1answer
413 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 ...
0
votes
1answer
17 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 ...
3
votes
2answers
1k views

Piping tcpdump traffic via SSH - but no root ssh access

The situation I would like to use Wireshark to analyze traffic on one of our servers, but I don't want to install Wireshark on the server itself. I understand that I can pipe tcpdump traffic via SSH ...
2
votes
1answer
241 views

How to update tcpdump?

I would like to update tcpdump on my computer (CentOS 6.5) which is currently old. I download the zip file from TCPDUMP/LIBPCAP public repository already but I don't know how to update with this file. ...
1
vote
0answers
267 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 ...
2
votes
0answers
1k 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 ...
1
vote
1answer
358 views

Capture web traffic grouped by individual TCP streams

As far as I know a HTTP request and response constructs one TCP connection. To debug a web application on a GUI-less server, I'd like to be able to capture these TCP streams in a single ...
2
votes
2answers
134 views

“tcpdump” to capture the last packets

I am monitoring a certain port, because my application uses that port, it seems that the connection drops at random times, I want to see what are the last packets passing through before the connection ...
1
vote
2answers
63 views

Remove pauses greater than x from pcap file

I've captured udp traffic to a pcap file. When replaying with tcpreplay-edit, I'd like to shorten all pauses (where there is no udp traffic at all) to x seconds max. tcpreplay-edit only has a global ...
1
vote
2answers
175 views

Do not display ACK packets

I have the following tcpdump -i eth0 -n tcp port 5000 to filter every packet flowing between 2 hosts. However, one of the hosts always sends an ACK. How do I hide this ACK?
1
vote
0answers
106 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
1answer
182 views

How to log incoming icmp traffic?

I am watching my ip6table and observing an icmp packet arriving and getting dropped at the rate of 1 per second. I am trying to find out what that message is about. I tried using tcpdump (it is ...
3
votes
1answer
195 views

tcpdump command works only on local ip

I am trying to capture some IP packets in my personal LAN with tcpdump, through the command tcpdump -A -i eth0 'tcp and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0) ...
2
votes
1answer
38 views

How to sniff download information of different pc's on a network(router)

Actually I am making an Log Analyzer for downloads on a network by different users.So i want to know who downloaded what in a same network.I know SSL packets cannot be sniffed but I want only ...
7
votes
3answers
1k views

How does one capture traffic on virtual interfaces?

I would like to capture traffic on Linux virtual interfaces, for debugging purposes. I have been experimenting with veth, tun and dummy interface types; on all three, I am having trouble getting ...
2
votes
3answers
965 views

How to record an interactice socat TCP/TLS session?

Socat is great for interactively testing line based human readable protocols like HTTP or IMAP. For example: $ socat -d -d READLINE,history=$HOME/s.hist openssl:host:port,crnl,cafile=some.ca For ...
2
votes
0answers
3k 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
117 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 ...
1
vote
1answer
982 views

tcpdump of SCCP or GSM MAP messages

Right now I'm using tcpdump -i <interface_name> -p <port> -s0 -w /tmp/file.cap and then filter the capture in wireshark. How can I take packet capture with tcpdump only on SCCP or GSM_MAP ...
1
vote
1answer
303 views

Processing FreeBSD's PF logs with tcpdump/sed/awk

I'm running FreeBSD and have PF firewall set up and this is command i use to display daily number of firewall hits (blocked traffic) sudo tcpdump -n -e -tttt -r /var/log/pflog | grep $(date ...
3
votes
1answer
163 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
291 views

How to rotate tcpdump files?

I want to take a continuous dump file of particular size and after the dump reached it predefined size the new data should overwrite the file. Help
1
vote
1answer
43 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 ...
2
votes
2answers
5k views

tcp dump outgoing connection packets

What is the command syntax to log all tcp connection packets? I am trying to see what address and ports my computer is trying to connect to outgoing so that I may config my firewall.
2
votes
3answers
855 views

Running tcpdump, tee and scp

I'm trying to run the following: $ tcpdump -l -X -i eth1 -n tcp port <port> | tee capture.txt | \ scp capture.txt root@10.3.3.227:/home/checker/ tcpdump -l -X -i eth1 -n tcp port ...
3
votes
3answers
582 views

tcpdump syntax error when specifying portrange as documented

I am using tcpdump on OpenBSD and trying to learn it from a primer on it. I want to capture a range of ports, but it seems how this is done has changed. I can't even find portrange as a keyword in ...