As soon as you get your initial foothold on the target server, your next step is to transfert text or binary files.
You'll probably download some target files and upload some tools such as backdoors or privilege escalation scripts...
Base64 encoding is the simplest way to upload small binary or text files.
cat file | base64 printf 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx' | base64 -d > file
Just prepare the last command on you xterm, it can be many lines long, then copy/paste/exec on you target.
To transfer a file without worrying about its size, just launch an HTTP server and make a wget, curl
python -m SimpleHTTPServer 8000 php -S 0.0.0.0:8000
Be carefull, eveyone is able to browse this new server file system.
With an ssh accès, let use scp
scp file.txt email@example.com:/remote/directory scp -i id_rsa file.txt firstname.lastname@example.org:/remote/directory scp -P 2222 file.txt email@example.com:/remote/directory scp firstname.lastname@example.org:/remote/file.txt /local/directory