To use tcpdump to monitor all traffic on the eth1 interface except for your own SSH session, you can use the not operator and specify the IP address of your own machine as an exclusion.
The not operator allows you to exclude traffic that matches a specified criterion.
For example, to monitor all traffic on the eth1 interface except for traffic to or from your own machine, you can use the following command:
$ tcpdump -i eth1 not host <your_ip_address>
Replace <your_ip_address> with the IP address of your own machine.
This will capture all traffic on the eth1 interface except for traffic to or from your own machine.
Alternatively, you can specify the port number of your SSH session as an exclusion.
For example, to monitor all traffic on the eth1 interface except for traffic to or from the port number used for your SSH session, you can use the following command:
$ tcpdump -i eth1 not port <ssh_port>
Replace <ssh_port> with the port number used for your SSH session. The default port number for SSH is 22, but it may be different on your system.
This will capture all traffic on the eth1 interface except for traffic to or from the port number used for your SSH session.
You can also use the and operator to specify multiple exclusions. For example, to exclude both your own IP address and the port number used for your SSH session, you can use the following command:
$ tcpdump -i eth1 not host <your_ip_address> and not port <ssh_port>
This will capture all traffic on the eth1 interface except for traffic to or from your own machine or the port number used for your SSH session.
Note that the tcpdump command is a powerful tool that allows you to capture and analyze network traffic. It is important to use it with caution and only with the appropriate permissions. If you do not have the necessary permissions, you may receive an error message or capture sensitive information.