configs/sshd_config

# Allow TCP forwarding (is usually enabled by default)
AllowTcpForwarding yes
# Allow Unix socket forwarding (again, usually enabled be default)
AllowStreamLocalForwarding yes


# Allow remote access to -R remote port forwards
GatewayPorts yes
# Optionally add it under "Match User <user>" to restrict who can do this.
# Another option is "GatewayPorts clientspecified", but I haven't persionally tested that.