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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Track IP Messenger's chatting by wireshark

We have Linux server ( RHEL 5 ), and some client machines ( Windows XP ) in local area network. We using server as proxy server. I am using squid proxy. My windows machines using internet by proxy. Now my client machines using IP messenger for…
Kumar
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Identify Executable Creating Network Traffic

I've got some application on my Windows XP machine that is generating an HTTP request to aaronsw.com every half hour. We've trapped the packets in wireshark, but wireshark doesn't tell what application generated the packets. Is there any utility…
jeffspost
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Understanding TCP RST Network Capture

I only really need help understand the following image, but I will give the background for context. We have an app that is configured to use a proxy on port 8080 and requires Internet access. At random times throughout the day, the app fails to…
Mucker
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Method of streaming a packet capture from a Windows machine

I have a Windows 10 VM on Hyper-V. It is a production system (yeah I know) that is running multiple critical services that I need to analyse so I can migrate it off to something better. I need to capture the network traffic on that system to ensure…
RoyT
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[Send mail with attachment]: TCP Retransmission, Duplicate ACK => TCP Reset

So, we have a linux box with postfix running on LAN site A which sends emails to an Microsoft exchange server sitting on site B. This runs perfectly when there is no attachment to the mail. But as soon as there is an attachment with a size of around…
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How to receive mirrored traffic on remote host using Ubiquiti EdgeRouterX?

I have the current network setup: two subnets are connected using an Ubiquiti EdgeRouterX, subnet 1 has a switch mirroring all traffic on that subnet to the router and on subnet 2 there is a host where I want to receive all the mirrored data. Using…
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ALPN negotiation fails

I am trying to connect two server to exchange data. I captured the packetes and they try to establish a connection but then are not sending data. Does someone know what the Problem could be? captured packages
Tobias
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Traffic capture at boot

I'm trying to figure out what packets a linux host sends at boot in order to debug it. Is there a way to start packet capture during boot time to not miss any packets? What is your way of going about it? I have found a red hat guide but it's behind…
lolz
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Capture filter filter with tcpdump/tshark

I'd like to filter ip messages which are constructed as follow (see picture below): GRE on top of IP GRE contains IP with UDP on port 1234 (in the picture below port 80). How can I filter such messages? PS operating system is windows based
user1977050
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How to identify source, destination ip using STUN and DTLS protocols?

enter image description here Given image i'm not able to identify which is source and destination ip address ( client or server). From STUN protocol 1st packet it's user request so i thought 131.202.240.150 is client ip address. From DTLS 5th packet…
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Where is the ACK to the packet in frame 76?

I am working through Kurose's book as part of a class and this particular exercise involves submitting a .txt file to the server and capturing this transfer and the server's response. In one exercise I have to choose the 1st 6 packets my pc sends,…
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Is there a way to disable TCP segmentation offloading to prevent packets greater than the MTU from being captured from the loopback interface?

I'm trying to create some captures on my linux box. The problem I have is that any captures I take from the loopback interface will contain massive packets that are much larger than the MTU. This appears to because of TCP segmentation offloading. I…
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Pcap (tcpdump) filter to match against local port

I'm trying to write a libpcap (tcpdump, iftop) filter that would match packets having a specific local port. That is, I'm interested in traffic that either goes out of port 12345 on the local machine or into port 12345 on the local machine. The…
intelfx
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Send duplicate UDP packets to another computer

We have a production server where we receive a continuous stream of UDP packets (~ 15 Mbps). We have a small research team which wants to process this same exact stream for some research purposes on another server. The research team's server is also…
Azeem Khan
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How do I capture packets on a Linux VM in a VMware environment?

I've got a Linux server that is a VM running on ESXi 6.7. We're running into some network trouble with it, and I'm trying to use tcpdump to capture traffic on the VM itself, but I'm getting only the traffic generated by the server, and not the…
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