Questions tagged [packet-capture]

Packet capture is the act of capturing data packets crossing a computer network. Packet capture can be: Deep packet capture (headers & payload), or partial packet capture (headers only).

Packet capture is the act of capturing data packets crossing a computer network. Deep packet capture (DPC) is the act of capturing, at full network speed, complete network packets (header and payload) crossing a network with a high traffic rate. Once captured and stored, either in short-term memory or long-term storage, software tools can perform Deep packet inspection (DPI) to review network packet data, perform forensics analysis to uncover the root cause of network problems, identify security threats, and ensure data communications and network usage complies with outlined policy. Some DPCs can be coupled with DPI and can as a result manage, inspect, and analyze all network traffic in real-time at wire speeds while keeping a historical archive of all network traffic for further analysis.

Partial packet capture can record headers without recording the total content of datagrams. This can reduce storage requirements, and avoid legal problems, but yet have enough data to reveal the essential information required for problem diagnosis.

Source: Wikipedia.

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Can Wireshark capture an entire Ethernet frame including preamble, CRC and Interframe spacing?

I am examining an Ethernet frame in Wireshark. According to the "Ethernet frame" Wikipedia article and accompanying diagrams, "A frame starts with a 7-octet preamble and 1-octet start frame delimiter (SFD)." The article also highlights that "[the]…
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Wireshark Capture Between Two Routers

How would one go about capturing OSPF traffic in Wireshark between two routers? I'm looking to do something like this: [RTR A] - - - [LAPTOP] - - - [RTR B]
THE DOCTOR
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Why do some machines respond with many RST packets instead of RST-ACK to refuse a connection?

I have recently been trying to track down a problem with one of our systems and have noticed that it is simply not allowed to connect to a remote machine. However, the remote machine (not controlled by us) is responding to our request for a…
Michael J. Gray
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What's a good proxy/tool to dynamically change the content of packets(TCP/UDP)

I am not sure if such tool exists, but I want to dynamically modify certain packets sent using my wireless network. More specifically, I want to modify packets sent from multiple machines (including phones), and possibly inject additional packets.…
Tony Stark
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VPN packet capture on ASA5505

Following up from a previous question regarding how to capture packets on the ASA5505 I'm having some difficulty in distinguishing which traffic has come through the VPN and which was generated from the firewall itself. To outline the problem, I…
James
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Flow of packets in network

I can't visualize in my mind the network traffic flow. eg. If there are 15 pc's in a LAN When packet goes from router to local LAN, do it passes all the computers? Does it go to the ethernet card of every computer and those computers accept the…
user58859
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CLI tool for analyzing pcap captures

I am looking for a command line tool that will look at a capture file, tcpdump -w output, and give output equivalent to the information you get in the Wireshark conversations, and endpoint statistics. To give you a little background, I have the…
Zoredache
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Wireshark won't pick up packets sent from localhost to localhost via network

I'm running on Windows and trying to get Wireshark to pick up my network traffic. It picks up all outbound and inbound traffic fine, except for a client/server I'm running on my local system. As it is, even when I'm sending packets through my LAN…
Rushyo
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pfSense: Possible to traffic capture the actual WAN port?

The pfSense router seems to have having problems connecting to the internet. My modem, and my ISP, confirm that i have sync, but at the same time pfSense sometimes just will not connect (using PPPoE). i want to try to debug the problem, by watching…
Ian Boyd
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how to man-in-the-middle blocking/intercepting/editing all network traffic going to a single cabled device and a server

I need to completely block and intercept and alter all packets going between two devices. possibly i need to isolate one device and block/intercept/edit ALL traffic going to and from it if i cannot find the cause in the packets between the devices.…
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What are the numbers preceeding a DNS packets flags for?

What does the Flags: 0x0500 section of this DNS query packet mean? Domain Name System (query) Transaction ID: 0x4242 Flags: 0x0500 Standard query 0... .... .... .... = Response: Message is a query .000 0... .... .... =…
Justin
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What should be the next sequence number after a packet with the FIN containing payload?

I was capturing some HTTP traffics and I observed a packet with the FIN flag set and also containing payload data. I searched for this topic and I found some similar questions but none of them talking about the next sequence number and RFC…
mrazimi
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How does LDAP Authentication Work at the TCP Layer?

Specifically, how does an LDAP server distinguish a TCP packet containing a SearchRequestOp from an authenticated user, from a TCP packet containing a SearchRequestOp from an unauthenticated user? I understand how the BindRequest and BindResponse…
Tikiyetti
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Can user credentials from HTTP session be seen through Wireshark?

Can we get that info the same way we do for FTP since HTTP is a plain text protocol?
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Can I verify failure of port forwarding using wireshark / packet capture

I've recently configured a Debian 9 server (Debian 4.9.130-2) to run as a lightweight server, running a series of Docker containers (nextcloud, sync, etc.) alongside basic services like ssh. Services are properly configured and running without…