This time I tried these excellent instructions and it worked right away on a debian lenny/sid box and Windows XP.
Configuring anonymous public shares with Samba 3
Let's recap that with Ubuntu 15.10 and Windows 7 amd64 SP1
# prepare directory sudo mkdir /opt/share sudo chown nobody:nogroup . # install samba sudo aptitude install samba # add samba share sudo sh -c "cat >> /etc/samba/smb.conf <<EOF [share] comment = Public Shares browsable = yes path = /opt/share public = yes writable = yes guest ok = yes EOF # configure anonymous access, sudo sed -i '/^\[global\]$/a \ guest account = nobody' /etc/samba/smb.conf