I ran into an OpenWRT router today. I SSH logged in, and found it didn’t have scp or rsync or ftp something like that. And it even didn’t have ssh client, so it was impossible to establish a reverse tunnel at all…can’t transfer files between my computer.

I did considered to opkg install these needed programs on it, but with only 64 MB space in total, 3 MB free then, I gave up.

Then, searched the web for a while, I found a dumb but useful idea, like this:
ssh root@opwrt 'cat /root/file' > ./file
And the code to upload files is:
cat ./file | ssh root@opwrt 'cat -> /root/file'

They worked pretty well. These files are small, so cat can handle them easily without any problems. Yeah, I like that, because this Keeps It Simple and Stupid.