what is packet sniffing

packet length, so the upper layer Protocol requires the LLC to indicate.In the Ethernet_II frame, change the length field of 802.3 to type. It is not necessary to implement the LLC Sublayer, which contains only a single Mac Sublayer, when the upper layer protocol is distinguished by the Type field.Only now the manufacturers are using Ethernet_II. The actual effe

Group First, let's look at the concept of the next grouping. The so-called grouping is to divide a packet into smaller packets. For example, for a 10GB packet, it is not always a one-time delivery of the past bar, but it is divided into a number of small packets sent past. S

Iris. Here, you can clearly see the MAC address, IP address, protocol type port number, and other details of the captured data packet. By analyzing the data, the network administrator can know what kind of data packets are active in the network. Note: The structure of the data packet is very complex. It

Let's start by recognizing what a packet loss is, and what kind of phenomenon is being lost to the network: Data is transmitted on the Internet on a packet-by-unit basis, w

What is the maximum size of each UDP packet?65507 approximately equal to 64KWhy is the maximum 65507?Because the UDP header has 2 bytes for recording the package body length. 2 bytes can indicate the maximum value is: 2^16-1=64k-1=65535UDP header accounted for 8 bytes, IP he

then receive the FIN packet from the other party. However, the closing status indicates that after you send the FIN packet, you have not received the ACK packet from the other party, but have also received the FIN packet from the other party. Under what circumstances will t

rid of a packet, you can also do log in the inside, do NAT, but the original intention of the Iptables framework does not allow you to do so but did not stop your behavior.We can see another detail in the details of the iptables execution flow (which is not drawn in the process above), namely that iptables is really not enough to just determine "match" in match,

the software on Windows has no control over the network devices. But what if we don't want to use a third-party tool like this? Or do you want to do some of your own processing when sending and receiving, filtering the underlying package, or even more complex logic in the drive layer? If so, the use of WinPcap is not enough, we need to write a driver to complete this task.3. Low-level

What's that NetScaler Reset Packet?https://www.citrix.com/blogs/2014/05/20/whats-that-netscaler-reset-packet/A few weeks ago I wrote a blog post on what to empower and extend your default Wireshark configuration titled NetScaler + WIreshark = A Perfect combination! I ' d like-to-follow up-that-post with this article which focuses on

The process of sk_buff encapsulation and Network Packet encapsulation is described in detail.It can be said that the sk_buff struct is the core of the Linux network protocol stack, and almost all operations are performed around the sk_buff struct, its importance is similar to that of BSD's mbuf (I have read "TCP/IP det

in a match inside a check code to get rid of a packet, you can also do log in the inside, do NAT, but the original intention of the Iptables framework does not allow you to do so but did not stop your behavior.We can see another detail in the details of the iptables execution flow (which is not drawn in the process above), namely that iptables is really not enou

. This process is problematic if the memory consumed by a process is larger than the CPU that is shown above. The network administrator will be able to troubleshoot these available processes individually. Seven, such as sometimes the network administrator can force some CPU-intensive processes to shut down, and then test whether the message loss has improved. If

the receiving buffer is large enough, then, package obtained from the receiving buffer is placed in a message queue. PS: it is best to mark the length of the entire package in the packet header when sending the packet to facilitate unpacking.The queue can be solved using

virtual machine.Throws a OutOfMemoryError exception if the virtual machine cannot request enough memory space in the expansion stackIt is important to note that the larger the stack size, the less the number of threads can be allocated.3, run a constant pool overflowException information: Java.lang.OutOfMemoryError:PermGen spaceThe simplest way to add content to a running constant pool is to use the String

The next-generation packet filtering framework following iptables is nftables.At night, I was prepared to go on to tell the story about Netfilter. The text was a little loose. Because I didn't draft a draft, I was a little confused about whether to boast or laugh at myself in one breath, right when I was a child, I like to write my diary every day. I used to copy a few boxes in the name of a retired employe