ptkl - Pseudo Terminal Key Logger

Beware! This is very early stage of LD_PRELOAD based pseudo terminal key logger.

It overwrites write and writev libc functions and copies all data as they are to a file descriptor 100 from them for all fds pointing to /dev/ptmx. File descriptor 100 is expected to be open in advance (use shell redirection 100>&2 for example). Every logged write is prepended with PID, function name, fd number and amount of written data. For example:

201: write: fd: 7: size: 1: s

where process with PID 201 wrote with function write to the file descriptor 7 one byte s.

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Build with

make

Run following command to log ssh sessions.

./ptklify /usr/sbin/sshd -De 100>&2

Docker test cheat sheet:

docker build --tag=sshd .
docker run --rm --name=sshd sshd
ssh -o UserKnownHostsFile=kh root@172.17.0.2