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34

Most home routers use a special-case of NAT called PAT. You'll also see it referred to as NAPT, or IP Masquerading. All three of the latter terms mean the same thing in general use. (The acronyms - Network Address Translation / Port Address Translation / Network Address Port Translation) When the packet goes out from your internal machine, the source ...


20

Even though the question has been fully covered. I feel like this process should best be described step-by-step. For this example, I sit in a private LAN connected to the Internet through a router. Because our network shares a single public IP address, we use NAT. So when I request the page superuser.com that will generate many IP packets. Let's look at a ...


16

Packet is an ambiguous term here because it is sometimes misused to refer to different elements for your transmission. Lets see what your data is wrapped up in and you'll see what I mean, and hopefully get the answer you wanted: Lets assume you're sending 1 byte of data1 over the internet, on the TCP/IP model. The data starts on the application level ...


11

You may enable packet forwarding by entering sudo sysctl -w net.inet.ip.forwarding=1 into the Terminal.


10

We say TCP segment is the protocol data unit which consists a TCP header and an application data piece (packet) which comes from the (upper) Application Layer. Transport layer data is generally named as segment and network layer data unit is named as datagram but when we use UDP as transport layer protocol we don't say UDP segment, instead, we say UDP ...


8

Yes, all communications out of the LAN will go through the firewall and can be intercepted/monitored. Encryption is one way to "hide" such communication, but it seems to me that if they're that paranoid about spying on you, then they'd simply block all encrypted connections anyway. I would suggest that you do not try to circumvent their monitoring. If you ...


6

ping packets are ICMP packets (IP protocol number 1) with a subtype of ECHO REQUEST or ECHO REPLY.


6

According to the page 99 of "Understanding MySQL Internals" (ISBN 0-596-00957-7), here are paragraphs 1-3 explaining it: MySQL network communication code was written under the assumption that queries are always reasonably short, and therefore can be sent to and processed by the server in one chunk, which is called a packet in MySQL ...


5

There is no default size, it varies, ranging from 20 to 65535 bytes including the minimal header size. An IP packet with a length of only 20 bytes is unlikely however, it would only be possible with a packet without payload or data. The header length can vary between 20 and 60 bytes, the header contains information about the packet/protocol and no actual ...


5

Wireshark will do that. It's an open source packet sniffer.


5

Each layer have its header, as you can see: Segments: Transport layer (TCP/UDP) = transport header + data (from uper layer) Packet: Internet layer (IP) = network header + transport header and data (both transport and data from upper layers) Frames: Network layer (Ethernet) = frame header + network , transport header and data (from three upper layers). ...


5

The term "packet" is normally used at the IP layer, and segment (TCP) or datagram (UDP) are used at the higher transport layer. It's common to refer to Ethernet frames, rather than Ethernet packets, so I think your 2nd-last paragraph is correct. MAC addresses are used to identify network interfaces at the data link layer, for devices which share the same ...


5

Network Address Translation. Briefly, when the private LAN's gateway router replaces the private LAN source address with its own public address, it modifies the packet in some way such as assigning a unique and otherwise locally meaningless port number which it maps back to the originating LAN node and outgoing request. It remembers this port mapping so ...


4

According to the RFC 793 Reset Generation rules: As a general rule, reset (RST) must be sent whenever a segment arrives which apparently is not intended for the current connection. A reset must not be sent if it is not clear that this is the case. There are three groups of states: 1. If the connection does not exist (CLOSED) then a reset is sent in ...


4

Everything will be a little slower over the VPN, since the connection naturally introduces several more hops to and from a remote location. For example, if you live in London, the VPN server is in USA, and you are connecting to another London-located server, then the packets will have to go overseas and back. Depending on the connection quality, the delay ...


4

Orbit Downloader handle MMS, RTSP and RTMP protocols. With its Grab Pro module it let you inspect http to find the link to the streamed media. It's a freeware and a good Download Manager. The firefox extension Video Download Helper could help too


4

Look at Wi-Fi (WLAN, IEEE 802.11) on the Wireshark Wiki page. See the CaptureSetup/WLAN page for instructions how to capture from WLAN's (including monitor mode), and see the CaptureSetup page for general information on capturing on WLAN's and other media. Going further, if you are using Windows (are you?) Capturing WLAN traffic on Windows depends ...


4

That's all way too hard if you're using Linux. Most wireless cards nowadays support monitor mode, which allows to use them to capture all packets, including 802.11 Management and Control frames, on a single channel. If your wireless card supports this mode (chances that it does), then do the following (I assume that you are using a Debian-based distro: $ ...


4

This is most likely down to the limitation of either the driver of the wireless card or most likely the wireless card itself. When I need to do this sort of thing, I use my wireless USB card. If Wireshark simply cannot access the card, this is why. If however you can access it but just can't see any data, try changing the wireless mode to open / non ...


3

Little Snitch can do this. If the process doesn't change its ports too often, you can get a list of the process' ports with $ lsof -i | grep <process name> Then use tcpdump. $ sudo tcpdump -i en1 port 80 > dump.txt Where en1 is your interface. $ ifconfig to get a list. $ man -t lsof | open -f -a /Applications/Preview.app $ man -t tcpdump ...


3

That is incorrect, there is no minimum size for a download. You can verify this by creating a tiny file on your webserver and using wireshark to watch the network traffic when you download that file. The minimum size of a standard ethernet packet is 64 bytes.


3

For windows I would suggest Replay Media Catcher .its shareware For linux rtmpdump - freeware CLI application (Mac OS X, Linux, Windows). It allows you to dump RTMP streams onto your hard drive. (or) Try here :http://all-streaming-media.com/faq/recording-media-stream/faq-record-download-capture-save-flash-flv-video-rtmp.htm


3

The original TCP RFC is kind of fuzzy with how it uses the term "segment". In some cases, the term "segment" refers to just the current piece of the application data stream that's being transmitted, which excludes the TCP headers. For example, the TCP "Maximum Segment Size" (MSS) is the maximum size of the application data chunk in this message, not ...


3

Wireless signals will be received and read by the lower level network software in all WiFi equipped computers in the vicinity. If the target computer is not the current computer the packets are discarded - unless the interface has been put into promiscuous mode. A packet-sniffer such as Wireshark can then capture and display the packet's data. This is ...


3

If configured correctly a sniffer will receive all packets it can decode and display them on the screen. This vulnerability is inherant in any WiFi signal that is suseptibale to any form of easedropping (e.g. being able to capture communications that are unencrypted, weakly encrypted, etc). This is most likely why many sites have added forced HTTPS which ...


2

If the VPN uses encryption, such as SSL or IPsec, then yes the network may be slower as the packets need to be encrypted and decrypted at each end. Whether this will interfere with your ability to carry out VOIP operations depends on the speed of the internet connection, how much bandwidth you give the application and the amount of CPU available on each end. ...


2

The minimum frame size for Ethernet is dictated at 64 bytes (as also described in your references). DMAC + SMAC + EtherType + Payload + CRC 6 + 6 + 2 + 46 + 4 = 64 At layer 4 (TCP or UDP) the 'length' covers the layer 4 header and it is tracked in the IP header. This means, for UDP the minimum expected is 8 bytes (for its header). ...


2

Unless your a valued business customer ISP's generally aren't going to be making any core routing changes for you. Basically it's out of your control, your ISP will be routing the packets to who they see as their "best" peer with a route to that destination network. That next network (ISP) will route it to their "best" peer, and so on until you eventually ...


2

Use the tc qdisc show command. The second field is the network scheduler. The default, pfifo_fast is basically first in, first out within a priority with higher priorities always going before lower priorities.


2

You could use a combination of nslookup and Wireshark. nslookup is a nameserver lookup utility available on most operating systems which allows you to query DNS servers. Wireshark is a network packet analysis tool. Using Wireshark you can capture just the DNS queries being sent by your computer and it will break down the DNS request packets to help you ...



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