Echo Requests and Responses

This step-by-step guide will help you understand how ICMP Echo Requests and Responses work using the ping command and packet analysis with Wireshark.

Goal:

To analyze ICMP packets in a network, verify connectivity, and understand how devices communicate using Echo Requests and Replies.

Step 1: Network Setup

• Configure two devices (PC1 and PC2) on the same network.

• Assign IP addresses (PC1: 192.168.1.1):

PC1> ip 192.168.1.1/24
Checking for duplicate address...
PC1 : 192.168.1.1 255.255.255.0

PC1> show ip

NAME        : PC1[1]
IP/MASK     : 192.168.1.1/24
GATEWAY     : 0.0.0.0
DNS         :
MAC         : 00:50:79:66:68:00
LPORT       : 10004
RHOST:PORT  : 127.0.0.1:10005
MTU:        : 1500

• Assign IP addresses (PC2: 192.168.1.2)

PC2> ip 192.168.1.2/24
Checking for duplicate address...
PC1 : 192.168.1.2 255.255.255.0

PC2> show ip

NAME        : PC2[1]
IP/MASK     : 192.168.1.2/24
GATEWAY     : 0.0.0.0
DNS         :
MAC         : 00:50:79:66:68:01
LPORT       : 10002
RHOST:PORT  : 127.0.0.1:10003
MTU:        : 1500

Step 2: Using the Ping Command

• Verify the connectivity between both devices.

PC1> ping 192.168.1.2
84 bytes from 192.168.1.2 icmp_seq=1 ttl=64 time=1.032 ms
84 bytes from 192.168.1.2 icmp_seq=2 ttl=64 time=1.110 ms
84 bytes from 192.168.1.2 icmp_seq=3 ttl=64 time=1.167 ms
84 bytes from 192.168.1.2 icmp_seq=4 ttl=64 time=1.203 ms
84 bytes from 192.168.1.2 icmp_seq=5 ttl=64 time=1.249 ms

PC1>

Step 3: Capturing ICMP Packets with Wireshark

• Open Wireshark on PC1.

• Start capturing packets on the active network interface.

• Use the filter:

icmp

• Analyze the Echo Request (Type 8) and Echo Reply (Type 0) packets.

Step 4: Analyzing the Packet Details

• Echo Request (Sent by PC1):

  • Type: 8 (Request)

  • Code: 0

  • Identifier & Sequence Number

• Echo Reply (Received from PC2):

  • Type: 0 (Reply)

  • Code: 0

  • Same Identifier & Sequence Number

Step 5: Troubleshooting Network Connectivity Issues

• If there is no response:

  • Check firewall settings (ICMP might be blocked).

  • Ensure IP addresses are correctly assigned.

  • Verify physical and network connectivity.

Keywords:

ICMP, ping command, echo request, echo reply, Wireshark, network troubleshooting, packet analysis, network connectivity, Type 8, Type 0, ICMP filter, identifier, sequence number, packet capture, network diagnostics, firewall settings, network interface, IP configuration, connectivity issues, network security, وایرشارک