ethertype

Ethertype is a field in an ethereframe. It is used to specify the Protocol applied to the frame data field. According to 802.3, the length/ethertype field is a field of two eight character segments. The meaning of the two is one, depending on the value. In quantitative evaluation, the first eight-byte field is the most important. When the field value is greater than or equal to the decimal value 1536 (that

:16:EC:AF:CB:CB inet addr:10.0.1.3 Bcast:10.255.255.255 Mask:255.255.255.0 inet6 addr: fe80::216:ecff:feaf:cbcb/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:4564 errors:0 dropped:0 overruns:0 frame:0 TX packets:6688 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:459463 (448.6 KiB) TX bytes:546633 (533.8 KiB) Interrupt:23 Base address:0x6000 When I ping mach

protocol (Dial Up/Modem ):576 bytesPoint-to-Point:4470 bytesIf the IP layer needs to transmit a datagram larger than the MTU of the link layer, the IP layer will split the datagram. A datagram is divided into several parts. The size of each part is smaller than or equal to the MTU value of the link layer. When hosts on the same network communicate with each other, the MTU of the network is very important to both parties. However, when a host can communicate through many networks, the most impor

Ethertype: Ethernet Type field and ValueEthertype is a field in an ethereframe. It is used to specify the Protocol applied to the frame data field. According to 802.3, the length/ethertype field is a field of two eight character segments. The meaning of the two is one, depending on the value. In quantitative evaluation, the first eight-byte field is the most important. When the field value is greater than o

/s1# IP netns exec MySpace route-nkernel IP Routing tabledestination Gateway genmask Flags Metric Ref use Iface0.0.0.0 192.168.45.2 0.0.0.0Ug0 0 0veth2192.168.45.0 0.0.0.0 255.255.255.0U0 0 0Veth2The first one is explicitly created, and the second is automatically created.Now you can ping the address of the extranet from MySpace.2 Principle 2.1 about eighth article SNATIf no eighth SNAT is set, the ICMP Request can reach the other computer, but the E

is used to verify frames. If the verification fails, it is discarded, only qualified data frames are received by the NIC, so CRC fields are not managed. Therefore, the key to parsing Ethernet data frames is to obtain the type field, and then submit the data of the data field to the upper-layer protocol for Processing Based on the Type field. Save the destination MAC address and source MAC address for subsequent use. According to 802.3, the Ethernet Type field (

destination IP address is not changed or VIP, if this VIP address is not configured on the realserver, the packet will be discarded directly. therefore, you must configure a VIP with a 32 mask on the realserver, as shown below: ifconfig lo:1 VIP netmask 255.255.255.0 up However, when someone asks who's IP address is 192.168.81.229, both network adapters say that I am my network adapter. who should I send it?FirstNow, see the figure: #tcpdump -e -nn host 192.168.81.229tcpdump: verbose output sup

255.255.255.0 up However, when someone asks who's IP address is 192.168.81.229, both network adapters say that I am my network adapter. who should I send it?FirstNow, see the figure: #tcpdump -e -nn host 192.168.81.229tcpdump: verbose output suppressed, use -v or -vv for full protocol decodelistening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes22:27:50.720431 00:50:56:92:05:b9 > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 42: arp

)//-------------------------------------------------------------------------Void packetchecksum (unsigned char packet []){Dlc_header * pdlc_header = NULL; // Ethernet header pointerIp_header? * Pip_header = NULL ;? // IP header pointerUnsigned short attachsize = 0; // The total length of the transport layer protocol header and additional data ? Pdlc_header = (dlc_header *) packet; ? // Determine the ethertype. If it is not an IP package, it will not b

will know ^_^ ). DLC Header Field Length (byte) Fill Value Receiver Mac 6 Ffffffffff Sender MAC 6 Aaaaaaaaaaaa Ethertype 2 Zero X 0806 Figure 3 the content of the DLC header in the ARP request packet follows the ARP frame. Operation CodeOf course it is 1, Sender's MacAnd IPOf course fill in our own, and pay attention to, here's Receiver IP AddressFill in the IP address we want

entries (never expire):Ciscoasa (config) # arp inside 192.168.1.120 0023.4ee0.7b6cEnable ARP Detection:Ciscoasa (config) # arp-inspection inside Enable floodCiscoasa (config) # arp-inspection outside Enable No-floodDisplays the ARP detection status for each interface:Ciscoasa (config) # show arp-inspectionInterface Arp-inspection Miss----------------------------------------------------Inside enabled FloodOutside enabled No-floodConfigure interface access lists (no detection, bidirectional disch

::neutron::securitygroup properties:des Cription: ' Security group for VM ' name: {get_param: ' Os::stack_name '} rules: [{direction: ' Ingress ', Remot E_ip_prefix: ' 0.0.0.0/0 ', port_range_min:0, port_range_max:30000, Ethertype:ipv4, protocol: ' TCP '}, {direction: ' Egress ', Remote_ip_prefix: ' 0.0.0.0/0 ', port_range_min:0, port_range_max:65535, et Hertype: ' IPv4 ', protocol: ' TCP '}, {direction: ' Egress ', Remote_ip_prefix: ' 0.0.0.0/0 ', port_range_min: 0, port_range_max:65535,

"001636" for the hardware device of the first three bytes ", the last three bytes are randomly generated. Source code location: Dhcpstarv-0.2.1/src/main. c: 130 rows Unsigned char vendor_mac_prefix [] = {0x00, 0x16, 0x36 }; However, the source MAC of the Ethernet frame is the real MAC of the NIC that sends the data frame. Therefore, to locate the source of the DHCP Request Packet forged by Dhcpstarv, you can capture packets, determine the location of Dhcpstarv based on the source MAC in the Et

Let's look at the definition of ARP.Now Linux runs this commandTcpdump-i eth0:1-ent ' (DST 192.168.5.190 and src 192.168.5.109) or (DST 192.168.5.109 and src 192.168.5.190) '-Xbc:ee:7b:9d:ee:02 > Broadcast, EtherType ARP (0x0806), length 60:request Who-has 192.168.5.190 tell 192.168.5.109, Len Gth 460x0000:0001 0800 0604 0001 bcee 7b9d ee02 c0a80x0010:056d 0000 0000 0000 c0a8 05be 0000 00000x0020:0000 0000 0000 0000 0000 0000 000040:16:7e:79:c7:36 > B

Sender MAC6aaaaaaaaaaaa Sender IP4192.168.0.1 Recipient mac6bbbbbbbbbbbbbb Receiver IP4192.168.0.99 Fill data 180 Content of ARP frames in ARP response packets In this way, the IP address ing about 192.168.0.1 will be added to the ARP cache of 192.168.0.99. Now, it's time for programming to implement it. ^_^ Ii. Programming Implementation of ARP packet sending 1. fill data packets The above tables about the various fields of the ARP packet correspond to the struct in the program, correspond

Nova and neutron are OK, but still feel good with neutron.Import Neutronclient.v2_0.client as NeclientNeutron = neclient. Client (username= ' admin ', password= ' password ', tenant_name= ' admin ', auth_url= ' http://ip:5000/v2.0 ') S1 = Neutron.create_security_group (body={' security_group ': {' name ': ' Block '}}) for r in s1[' Security_group '] [' security_ Group_rules ']: Neutron.delete_security_group_rule (security_group_rule=r[' id ')) SGS = Neutron.list_security_groups ( ) [' security_g

does not necessarily open telnet, but can still trigger ARP request, Tcpdump returned as follows:Listening on Wlan0, Link-type EN10MB (Ethernet), capture size262144bytes the: One:37.230876 9C:4E: $: C6:e8: the(Oui Unknown) > Broadcast, EtherType ARP (0x0806), length the: Request Who-has172.28.185.136Tell172.28.185.203, length - the: One:37.278147Ac -:3D:B2:C0:B4 (Oui Unknown) >9C:4E: $: C6:e8: the(Oui Unknown), E