Its important to note that while software like keyloggers could be installed on an nit it would require the user to install it. This is why one should only install software from trusted sources. One of the advantages of open source software is that if you have the skills you can look at what the software does, so you could find out if it had maliscious code in it.

Its also important to note that because of the linux architecture no software can be automatically be installed from visiting a website as you have to set any file downloaded as executable.