traceroute icmp

, It is then referenced in the input chain, which is less efficient and easier to maintain.Chain INPUT (Policy ACCEPT)Target Prot opt source destinationRh-firewall-1-input All--0.0.0.0/0 0.0.0.0/0 Chain FORWARD (Policy ACCEPT)Target Prot opt source destinationRh-firewall-1-input All--0.0.0.0/0 0.0.0.0/0 Chain OUTPUT (Policy ACCEPT)Target Prot opt source destination Chain Rh-firewall-1-input (2 references)Target Prot opt source destinationACCEPT All--0.0.0.0/0 0.0.0.0/0ACCEPT

with a remote machine. It is implemented via Internet Control Message Protocol ICMP. And now some hosts filter ICMP, in this particular case, it is possible to make some hosts ping impassability, but can establish a network connection. This is a special case that is explained in advance. Again, this does not list all the optional parameters of the ping command, but it is an example to illustrate some of th

IP packet with a TTL value of 0, which sends an ICMP "time-out" message to the host that has the IP packet, and the host receives the IP address of the route at the same time that the ICMP packet has been received.Traceroute principle: It first constructs a TTL value of 1 data packets sent to the destination host, the packet on the first router, the router first to reduce the TTL value of 1 to 0, and then

Common Linux Network Tools: mtr for Route Scanning In addition to traceroute introduced in the previous article "common network tools for Linux: traceroute for Route scanning", Linux also has another commonly used route scanning tool mtr. Mtr is more useful than traceroute in some aspects. It can display the information of each hop route in real time and contin

Verification:View the routing table, and PING loopback interface for each router. R2r2# : show ip RouteCODES:C-connected, s-static, R-rip, M-mobile, B-BGPD-EIGRP, Ex-eigrp External, O-OSPF, IA-OSPF Inter areaN1-OSPF NSSA External Type 1, N2-OSPF NSSA external type 2E1-OSPF external Type 1, E2-OSPF external type 2I-is-is, Su-is-is Summary, L1-is-is level-1, L2-is-is level-2Ia-is-is Inter area, *-candidate default, U-per-user static routeO-ODR, P-periodic downloaded static routeGateway of last re

minimal local latency is an important way to optimize.Network latency, not bandwidth, is a performance bottleneck for most Web sites! To understand why, we need to understand the TCP and HTTP protocols-we'll cover this topic later in the chapter. However, if you are curious, you can jump directly to:"Higher bandwidth is not the key." Measurement delay with tracerouteThe Traceroute program is a simple network diagnostic tool used to record the routing

192.168.1.1Via Eth0 interface, send ARP request, query IP for 192.168.1.1 device MAC addresssudo arp-scan-lQuerying the corresponding MAC address of all IP addresses within the entire LANsudo tcpdump-i en0 ARPListening for ARP protocol communication on the En0 interfaceNetwork LayerThe network layer is a wide-area internet, the Internet equipment with IP address identification. Ping is a echo_request request to send an ICMP protocol to an IP address.

Command Ping is used to test the network accessibility and connectivity. It can be used in EXEC mode and Privileged EXEC mode. IP ping uses the ICMP protocol to provide connectivity and likelihood information. By default, only five echo messages are sent. The Ping extension options include: source IP address, service type, data, and Baotou. Ping Response Character Set Character Interpretation ! Received an echo-reply message Q Source quench . Timeout

do not list the source addresses. Note: You can use 101 filter in the inner direction of the external interface. 2. prevent external illegal Detection Illegal visitors often use ping or other commands to detect the network before initiating an attack on the internal network. Therefore, they can prevent attacks by Using ping, traceroute, and other network probes from outside. You can create the following access list: Access-list 102 deny

streams whose source address is private.　 access-list 101 deny ip 127.0.0.0 0.255.255.255 any/pre> Block all communication streams whose source address is the loopback address. access-list 101 deny ip 224.0.0.0 7.255.255.255 any　 Blocks all communication streams with the source address as a multi-destination address. 　access-list 101 deny ip host 0.0.0.0 any Blocks communication streams that do not list the source addresses. Note: You can use

view and Configure TCP/IP networks. Command instance: # Ifconfig eth0 Eth0 Link encap: Ethernet HWaddr 00: 0C: 29: FB: E4: 89 Inet addr: 192.168. 1.3 Bcast: 192.168. 1.255 Mask: 255.255.255.0 Inet6 addr: fe80: 20c: 29ff: fefb: e489/64 Scope: Link Up broadcast running multicast mtu: 1500 Metric: 1 RX packets: 36 errors: 0 dropped: 0 overruns: 0 frame: 0 TX packets: 139 errors: 0 dropped: 0 overruns: 0 carrier: 0 Collisions: 0 FIG: 1000 RX bytes: 4321 (4.2 KiB) TXbytes: 13153 (12.8 KiB) Interrupt

view and Configure TCP/IP networks. Command instance: # Ifconfig eth0 Eth0 Link encap: Ethernet HWaddr 00: 0C: 29: FB: E4: 89 Inet addr: 192.168. 1.3 Bcast: 192.168. 1.255 Mask: 255.255.255.0 Inet6 addr: fe80: 20c: 29ff: fefb: e489/64 Scope: Link Up broadcast running multicast mtu: 1500 Metric: 1 RX packets: 36 errors: 0 dropped: 0 overruns: 0 frame: 0 TX packets: 139 errors: 0 dropped: 0 overruns: 0 carrier: 0 Collisions: 0 FIG: 1000 RX bytes: 4321 (4.2 KiB) TXbytes: 13153 (12.8 KiB) Interrupt

TTL TTL is a value in the IP protocol package. It tells the network whether the packet is discarded because the time in the network is too long. There are many reasons that the package cannot be delivered to the destination within a certain period of time. The solution is to discard the packet after a period of time and then send the packet to the sender, which determines whether to resend the packet. The initial value of TTL is usually the default value of the system, which is the 8-bit domain

ports should not be assigned to services. In fact, machines typically allocate dynamic ports from 1024. But there are exceptions: Sun's RPC port starts at 32768.This section describes the information that typically TCP/UDP ports are scanned in the firewall record. Remember: There is no ICMP port. If you are interested in interpreting ICMP data, see the other parts of this article.0 is typically used to ana

Traceroute Access-list 112 permit ICMP any 150.150.150.0 0.0.255 administratively-prohibited Access-list 112 permit ICMP any 150.150.150.0 0.0.255 echo Access-list 112 permit TCP host 150.150.150.2 host 150.150.150.1 EQ Telnet Access-list 112 deny ip 127.0.0.0 0.20.255.255 any Access-list 112 deny ip any ! Line con 0 Transport input none Line au

rate is 100 percent (5/5), round-trip min/avg/max = 108/200/272 MS R1 # ping 1.1.1.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 1.1.1.2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 60/126/184 MS The RTT value when pinging R2. Traceroute 1.1.1.1 on R1: R1 # traceroute 1.1.1.1 Type escape s

:255.255.255.0Inet6 ADDR:FE80::20C:29FF:FEFB:E489/64 Scope:linkUp broadcast RUNNING multicast mtu:1500 metric:1RX packets:36 errors:0 dropped:0 overruns:0 frame:0TX packets:139 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:1000RX bytes:4321 (4.2 KiB) txbytes:13153 (12.8 KiB)Interrupt:10 Base address:0x1400#ifconfig eth0 192.168.1.3 netmask 255.255.255.0(2) Route commandThe route command is used to set routing information for a Linux systemTo view routing information:Route-nAdd a

.-T Survival value: Sets the size of the Live value TTL.TTL: Time To LiveSpecifies the number of network segments that the datagram is allowed to pass before it is discarded by the router.The TTL is set by the sending host to prevent packets from continually looping on the IP internetwork forever. When forwarding IP packets, the router is required to reduce the TTL by at least 1.The TTL field value can help us identify the operating system type.L Unix and Unix-like operating systems the TTL fiel

Linux itself provides many tools for network testing, network troubleshooting, network State analysis, and a few more commonly used tools.One, ping commandThe ping command uses the ICMP protocol to also test the connectivity of the network.Command format: ping [option] IPCommon options:-C #: Specify the number of messages;-W Timeout: The timeout of waiting for the response message.650) this.width=650; "title=" 1452726244909914.jpg "alt=" 1.jpg "src="

Network Engineering Test 1 Experiment 1: use of network protocol analysis tool Wireshark (Preview part) 1. Download the Installation File of Wireshark from the course website and install Wireshark on a computer in your dormitory. If you do not have a computer, please do this with your computer. (1) Answer the installation steps of Wireshark; (2) Answer the simple usage of Wireshark Based on the PPT in this course; (3) try to use the display filter and capture filter, think about and answer the d