FROM alpine:latest
RUN apk add openssh
RUN ssh-keygen -A && \
    sed -i 's/GatewayPorts no/GatewayPorts yes/' /etc/ssh/sshd_config && \
    sed -i 's/AllowTcpForwarding no/AllowTcpForwarding yes/' /etc/ssh/sshd_config && \
    printf "<censored>\n<censored>\n" | adduser anon
CMD [ "/usr/sbin/sshd", "-D" ]