igmp snooping

Theoretical technology: TCP/IP protocol family (4) ICMP and IGMP protocol!I should first talk about the IP protocol. Later, considering the hierarchy, I should explain the support protocol in detail! Because IP is my favorite and also my pain! Haha! I. ICMP protocolWhy use ICMP! What is the reason for using ICMP?The IP address cannot be used! IP addresses cannot provide error control and auxiliary mechanisms (such as host management and query )!For th

the role of multicast and IGMP---------------------------------The so-called multicast, as opposed to unicast and broadcast, refers to the network host will send the data at once to multiple target hosts belonging to the same group. The main use of the IGMP protocol. IGMP is the meaning of Internet Group Management protocol. The protocol is used toThe multicast g

addresses, for example, Ping 224.0.0.2.Reply from 192.168.11.1: bytes = 32 time Reply from 192.168.11.1: bytes = 32 time Reply from 192.168.11.1: bytes = 32 time Reply from 192.168.11.1: bytes = 32 time Reply from 192.168.11.1: bytes = 32 time Reply from 192.168.11.1: bytes = 32 time Reply from 192.168.11.1: bytes = 32 time We can see that this ping only returns a response from one IP address. This is the address of my gateway, which also verifies that 224.0.0.2 is the multicast (Multicast) add

Catalogue IP protocol Header formatAddress Resolution Protocol ARPReverse Address Resolution Protocol RARPInter-network Control Message Protocol ICMPInternet Group Management Protocol IGMP IP datagram header IP Datagram Header format: The highest bit is on the left and is recorded as 0 bit; the lowest bit is on the right . version: 4 bits, refers to the IP protocol version of the current IP protocol version number is 4 (that is, IPV4) Header Length

IP protocol Header formatAddress Resolution Protocol ARPReverse Address Resolution Protocol RARPInter-network Control Message Protocol ICMPInternet Group Management Protocol IGMP IP Datagram HeaderIP Datagram Header format:The highest bit is on the left and is recorded as 0 bit; the lowest bit is on the right.Version:4 bits, refers to the IP protocol version of the current IP protocol version number is 4 (that is, IPV4)Header Length:4 bits, the

First introduce/Proc/Sys/Net/IPv4/Conf/Eth0/Force_igmp_versionFile. If you want to change the IGMP version, you need to set this file. # Cat/Proc/Sys/Net/IPv4/Conf/Eth0/Force_igmp_version#0 0 indicates the maximum valid version number. Currently, the maximum version number is V3 by default. # Echo"2" > /Proc/Sys/Net/IPv4/Conf/Eth0/Force_igmp_version # Cat/Proc/Sys/Net/IPv4/Conf/Eth0/Force_igmp_version#2 2 indicates

In a cisco network environment, when a device with dhcp snooping enabled is configured for a boot request, option 82 is inserted into the DHCP packet (for details, see RFC3046 ). In this case, the gateway ip address in the packet in the boot request is 0, so once the dhcp relay device detects such a packet, it will discard it. Although dhcp snooping is used to prevent illegal dhcp server access, it plays an

You should have some knowledge about DHCP Snooping. For this part of knowledge, we will first explain the basic content, briefly introduce it to you, and then explain in detail the configuration of DHCP Snooping, hoping to help you. 1 Introduction DHCP Snooping is a security feature of DHCP. It filters untrusted DHCP information by creating and maintaining a DHCP

field is MF (more Fragment) Mf=1 indicates "There are shards" later. Mf=0 represents the Last Shard Df The one in the middle of the Flag field is DF (Don ' t Fragment) Shards are allowed only when df=0 Chip Offset:Occupies 12 bits, which refers to the relative position of a piece in the original group after the Shard. Slice offset in 8-byte offset unitsSurvival time:The maximum number of routers that are recorded as TTL (Time to Live) datagrams in th

mask of the destination network to distinguish it from the broadcast address that points to the network. The subnet number pointing to the broadcast address of all subnets and the host number is all 1. For example, if the destination subnet mask is 2 5. 2 5 5. 2 5 5. 0, so I P address 1 2 8. 1. 2 5 5. 2 5 is a broadcast address pointing to all subnets. However, if the network is not divided into subnets, It is a broadcast pointing to the network.3. MulticastFigure 1 2-2 shows the format of clas

allow incoming echo requests. IGMP Protocol (Internet Group Management ProtocolInternet Group Management Protocol). This protocol runs between the host and the multicast router directly connected to the host. It is a protocol used by the IP host to report the identities of multicast Group members. Through the IGMP protocol, on the one hand, you can use the IGMP

Many may know about the DHCP Snooping technology. So many friends still don't know about this part of content. Here we will give a detailed explanation of DHCP Snooping. 1 Introduction DHCP Snooping is a security feature of DHCP. It filters untrusted DHCP information by creating and maintaining a DHCP Snooping binding

Dhcp snooping SummaryConfiguration on a cisco deviceIn a cisco network environment, when a device with the dhcp snooping feature enabled, the boot request inserts option 82 in the DHCP packet. For details, see RFC3046, the gateway ip address in the packet in the boot request is 0, so once the dhcp relay device detects such a packet, it will discard it.Although dhcp s nooping is used to prevent illegal dhcp

the subnet.3.IGMP Protocol: Internet Group Management ProtocolThe role of IGMP is to let all other hosts and routers that need to know which multicast group they are in are aware of their state. In general, multicast routers do not need to know how many hosts are in a multicast group, as long as they know that there are no hosts in a multicast group on their subnets. As long as a single multicast group als

In the process of setting DHCP, we should pay attention to some special points. Just like the static IP dhcp snooping and IP Source Guard we will explain below. Because IP Source Guard cannot be used together with dynamic DHCP, you need to set static effects. Clock timezone WST 8 Switch 1 provision ws-c3750g-48ts System mtu routing 1500 Ip subnet-zero ! Ip dhcp snooping vlan 1 (specify the vl

In the previous article, we have explained the DHCP Server settings and DHCP Relay settings of the H3C switch. Here we will explain the last part -- DHCP Snooping configuration of the H3C switch. H3C switch DHCP Snooping configuration 1> Configure Environment Parameters 1. The DHCPServer is connected to port G1/1 of the SwitchA vswitch. It belongs to vlan10 and its IP address is 10.10.1.253/24. 2. Ports E0/

IP/IGMP/UDP checksum algorithm and algorithm: the IP, IGMP, UDP, and TCP packet headers both have validation fields, and their algorithms are the same. The range of IP, IGMP, UDP, and TCP checksum: only the length of the packet header. When sending data, in order to calculate the packet inspection. Perform the following steps: 1. Set the checksum field to 0; 2. R

address as a multicast address, and the device driver of the source host converts it to the appropriate MAC address and sends it. The process at the receiving end needs to tell its IP layer that it wants to accept data from a multicast address, and the corresponding device driver sets up a data frame that can accept the corresponding MAC address. This completes the setup of both sides of the communication, and this process is called "joining a multicast group". Unlike UDP, typically a multicast

1. DHCP spoofing attacks 1. a DHCP attacker can also provide SERVER services in a VLAN. 2. DHCP attackers will respond to the DHCP Client's sending request information. 3. attackers will allocate IP addresses and other information and default gateways to DHCP clients. Note: Multiple DHCP servers in a VLAN may cause Address allocation conflicts. Ii. DHCP spoofing attack (DHCP SnoopingDHCP listener) 1. DHCP Snooping allows you to configure the trusted

DHCP Snooping plays a critical role in the DHCP protocol. This part is involved in many settings. Now let's take a look at the knowledge of DHCP Snooping configuration. We hope to give everyone a new understanding. DHCP Server Spoofing The attacker sets up an illegal DHCP server on the vswitch and sends the IP address to the DHCP server from which the client sends the IP address in the client network. T