packet tracer

I. Overview: 1. ICMP agrees to report errors on the host or route and provides relevant exceptions. ICMP is a standard protocol for the Internet, but ICMP is not a high-level protocol, but an IP layer protocol. Generally, ICMP packets are used by the IP layer or higher-level protocols (TCP or UDP. Some ICMP messages return error messages to the user process. 2. The ICMP packet is used as the data of the IP layer datagram, And the header of the datagr

During the packet capture module, we have seen some data packet interception methods as follows:1. Use the pcap software package. The Linux version of pcap is the Libpcap function library, and the corresponding function library in Windows is Winpcap. The protocol analysis software etheral is implemented based on this software package (but not limited.2. Use the original socket. For example, the UDP proxy se

Basic use of the packet capture tool EtherealThis is a tutorial written by enthusiastic people on the Internet. I have put it into practice and it is very simple, but the basic work is enough. I will organize it for the moment.You can perform basic packet capture according to the steps. 1. Use the prefix parameter settings -- capture option settings Interface: Specifies the interface (NIC) on which the

The protocol number for OSPF is 89, and when OSPF packet multicasting occurs, their TTL is set to 1,1. Packet headerAll OSPF packets are started by a 24-byte eight-bit group header650) this.width=650; "Style=" Background:url ("/e/u261/lang/zh-cn/images/localimage.png") no-repeat Center;border : 1px solid #ddd; "src="/e/u261/themes/default/images/spacer.gif "alt=" Spacer.gif "/>650) this.width=650; "Style="

this This paper mainly introduces the realization of WEBRTC in Nack, Weizhenwei, the article was first published in the Wind network , Id:befoioSupport original, reprint must indicate the source, welcome attention to my public number blacker (Id:blackerteam or WEBRTCORGCN).In WEBRTC, forward error correction (FEC) and packet loss retransmission (NACK) are important methods to resist network errors. FEC adds a redundant error-correcting code to the

Traditional Campus Network Services lacks effective E2E locating methods, resulting in long fault diagnosis time and difficulty, making it difficult to meet user requirements. Network Performance Fault Diagnosis and quality evaluation are very important. Currently, many research groups and standards organizations are engaged in technical research and standard formulation. IETF has developed RFC5357 (A Two-Way Active Measurement Protocol) and RFC4656 (A One-way Active Measurement Protocol (OWAMP

I. Overview: 1. ICMP agrees to report errors on the host or route and provides relevant exceptions. ICMP is a standard protocol for the Internet, but ICMP is not a high-level protocol, but an IP layer protocol. Generally, ICMP packets are used by the IP layer or higher-level protocols (TCP or UDP. Some ICMP messages return error messages to the user process. 2. The ICMP packet is used as the data of the IP layer datagram, And the header of the datagr

I. Overview: 1. ICMP agrees to report errors on the host or route and provides relevant exceptions. ICMP is a standard protocol for the Internet, but ICMP is not a high-level protocol, but an IP layer protocol. Generally, ICMP packets are used by the IP layer or higher-level protocols (TCP or UDP. Some ICMP messages return error messages to the user process. 2. The ICMP packet is used as the data of the IP layer datagram, And the header of the datagr

Code protocol structure definition---------------------------------------# Pragma pack (1) // enters the byte alignment ModeTypedef struct framheader_t{// The data frame header captured by pcapByte dstmac [6]; // target MAC addressByte srcmac [6]; // source MAC addressWord frametype; // Frame Type} Framheader_t;Typedef struct ipheader_t{// Ip address data HeaderByte ver_hlen; // version + Header LengthByte TOS; // service typeWord totallen; // The total length.Word ID; // IDWord flag_segment; //

I have answered a few questions I have submitted in blog posts and csdn. I found a solution code later: Now we need to use C # As a WebServices interface for C ++ to call.WebServices has been defined (only one of the simplest web methods is described here, and security verification is omitted ):Void process (byte [] request, out byte [] Response) (this parameter cannot be changed)Parameter description: the type of the received parameter byte []. The output parameter byte []. Based on the receive

Evaluation of several network packet capture tools and several toolsEvaluation of several packet capture tools by Bin Laden's brotherRecently, I wrote a CMD remote control that says I want to do something on the server.We all know that soft false positives, especially those reported by black software, are normal.For this reason, some people may not install software. Basically, they rely on themselves to ana

I. Overview: 1. ICMP agrees to report errors on the host or route and provides relevant exceptions. ICMP is a standard protocol for the Internet, but ICMP is not a high-level protocol, but an IP layer protocol. Generally, ICMP packets are used by the IP layer or higher-level protocols (TCP or UDP. Some ICMP messages return error messages to the user process. 2. The ICMP packet is used as the data of the IP layer datagram, And the header of the datagr

I. Overview: 1. ICMP allows the host or route to report errors and provide relevant exceptions. ICMP is a standard protocol for the Internet, but ICMP is not a high-level protocol, but an IP layer protocol. Generally, ICMP packets are used by the IP layer or higher-level protocols (TCP or UDP. Some ICMP messages return error messages to the user process. 2. The ICMP packet is used as the data of the IP layer datagram, And the header of the datagram i

Ps:tcpdump is a tool for intercepting network groupings and outputting grouped content, which is simply the packet capture tool. With its powerful capabilities and flexible interception strategy, tcpdump is the preferred tool for network analysis and troubleshooting in Linux systems.Tcpdump provides source code, exposes interfaces, and is therefore highly extensible, and is a useful tool for network maintenance and intruders. Tcpdump exists in the bas

1. Packet forwarding rate of the switch The packet forwarding rate of the switch marks the size of the switch forwarding packet capability. Unit General bit BPS (packet per second), the packet forwarding rate for general switches ranged from dozens of kpps to hundreds of MP

Author: sodimethyl Source: http://blog.csdn.net/sodme statement: This article can be reproduced, reproduced, spread without the consent of the author, but any reference to this article please keep the author, source and this statement information. Thank you!The common network servers are basically 7x24. For online games, at least require the server to work continuously for more than a week and ensure that no catastrophic event such as server crash occurs. In fact, it is almost unrealistic to req

The 1th chapter, router-based packet filtering firewall General concepts of 1.1 packet filtering firewalls 1.1.1 What is a packet filter firewall A packet filtering firewall is a software that looks at the header of the packet that flows through it, thus determining the fate

I started the migration blog, the entire structure of the blog building and coding http://www.cookqq.com/lookBlog.action?id=c7d6978a-0dc0-4648-9020-2b81d859a243MySQL server recently always error, the content is as follows:The last packet successfully received from the server was 65,502,275 milliseconds ago. The last packet sent successfully to the server was 65,502,276 milliseconds ago. is longer than the s

Analysis of the causes of UDP packet loss in Linux system kernel1. UDP Checksum ErrorPhenomenon: You can use NETSTAT-SU to see that there is a UDP error packet.Tcpdump catch packet, open the captured UDP message in Wireshark, turn on checksum option, error packet.Scenario: Finding link Failure www.ahlinux.com2, Firewall OpenSymptom: A package for a specific port is not receivingScenario: Use service iptable

Internal network address 192.168.1.0/25 access to extranet does not restrict For intranet address 192.168.1.128/25 only allow to send and receive mail, do not allow access to extranet # sysname Routera # Firewall enable/enable firewall function Firewall default deny/configure firewall default action for deny/ # RADIUS scheme System # Domain system # ACL number 2000/define acl/for NAT conversion Rule 0 Permit Source 192.168.1.0 0.0.0.255 Rule 1 deny # ACL number 3001/define acl/for