ssh leviathan1@leviathan.labs.overthewire.org -p 2223
leviathan1_password

After running the ls command, we noticed a file named check, and then we executed it.
ls -la
./check

Next, we ran ltrace to observe how the program operates and noticed it performing a string-comparison function.
ltrace ./check

After that, we used the word we found to capture the flag.
./check
sex
whoami
cat /etc/leviathan_pass/leviathan2

Well done! This flag will take you to the next round.