Questions tagged [icmp]
For questions about the Internet Control Message protocol.
148 questions
2 votes
1 answer
131 views
ICMP Echo Response IP Header Copying
I have been reading up on ICMP recently. In RFC 792, it specifies that an ICMP Echo Response Packet is computed as follows: The address of the source in an echo message will be the destination of the ...
- 57
1 vote
1 answer
256 views
What are the extra 4 bytes (00 00 00 00) on a 1500 byte ICMP echo reply after a juniper router upgrade?
After a juniper router upgrade we started having MTU problems. I'm no longer able to send the router a 1500 byte ICMP packet (on a direct attached subnet with vlan) and get a reply. If I adjust the ...
- 11
2 votes
2 answers
213 views
Machine A configure a static arp When a ping msg with right mac address but wrong ip address from machine B. Does machine A give ping response?
Machine A arp list such as ip1:MAC1, ip2:MAC2; Machine b know ip and mac of machine A. But machine b configure mac1 and ip2 for itself. When Machine b send a ping msg to A. Does A give a response?
- 21
0 votes
1 answer
74 views
Packet loss between Host B and Router, but no packet loss between Host B and Host A or Host A and Router [closed]
I'm troubleshooting a packet loss issue with my IT department and am all out of ideas. I currently have the layer 2 folks blaming the layer 3 folks and vice versa - I'm just the guy caught in the ...
- 333
2 votes
1 answer
188 views
Do echo replies typically send out an ARP request?
When a host receives an ICMP echo message from an unknown IP on the same subnet, would it send an ARP request to determine the IP's associated MAC address? Or would it simply flip the source/dest MAC ...
- 21
1 vote
2 answers
102 views
Missing ICMP identifier equivalent in ARP protocol and desired arping behavior
Running simultaneously more arping on the same interface and the destination IP address all clients get the responses due missing ICMP identifier equivalent. First, am I correct that there is no ICMP ...
- 147
-1 votes
2 answers
112 views
Why MLS2 Doesn't Get ICMP Packet To Where It Should?
This is a Packet Tracer lab from Kieth Barker's website with minor modifications. It is intended to exhibit how can we get to the network 10.10.0.0/24 access to the Web Server 23.1.2.2/24 Using NAT. ...
- 295
0 votes
1 answer
165 views
In wireshark, why following a TCP or UDP stream does not remove ICMP packets?
In Wireshark, when I follow a TCP or UDP stream using right click -> Follow -> UDP Stream, if there are some ICMP packets from same endpoints, wireshark will keep them in the stream. Why? Since ...
0 votes
3 answers
438 views
Do destination hosts decrement the TTL?
I was trying to understand more about traceroute when I stumbled upon this site and I have a question about this diagram: As you can see in the diagram, the destination host S1 receives a packet ...
- 531
0 votes
1 answer
223 views
In a trace route, do routers that do not respond still forward the packets?
In traceroute, The sender expects a reply within a specified number of seconds. If a packet is not acknowledged within the expected interval, an asterisk is displayed. Pasting here the example trace ...
- 531
1 vote
1 answer
211 views
The TTL and packet drop [duplicate]
I would just like to verify one thing. When a router receives a packet with a TTL of 1, the router can still process and accept it if its destined for itself, correct? Because for example, eBGP ...
- 1,031
0 votes
1 answer
181 views
BGP configuration multi-hop ping not working
I'm learning bgp and studying on a simple lab I'm unable to ping a loop0 two hops away while the loop0 on the nex-hop router is reachable Topology is simple R3-R1-R2, from R2 i'm able to ping loop0 on ...
- 5
0 votes
2 answers
3k views
Why am I not capturing any ICMP packets on wireshark?
I am doing a lab where we are meant to ping an address and use wireshark to capture ICMP packets when we ping that address. WHen I run the wireshark capture with the ICMP filter on and ping my address,...
0 votes
1 answer
190 views
Change source and destination adresses from a valid captured ping to create a valid ping with different source and destination
I want to create traffic in my network, especially I want to send a repetitive ping to the device with the IP 192.168.3.146 from my traffic generator (IP 192.168.3.100) (see scematic) For the creation ...
0 votes
1 answer
218 views
ICMP error message's data for IP datagram with < 64 bits payload?
RFC792: The internet header plus the first 64 bits of the original datagram's data. This data is used by the host to match the message to the appropriate process. If a higher level protocol uses ...
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