Run the command "curl -X POST -d "@file.txt" "http://127.0.0.1:<random number between 100 and 999>/payload"; by randomly selecting a number between 100 and 999.
shuf -i 100-999 -n 1 | xargs -I {} echo 'curl -X POST -d "@file.txt" "http://127.0.0.1:{}/payload";'