Q I'm using a Fedora system and thought of upgrading to the latest version. Before doing this I loaded it onto a separate machine to see how it was configured off the disk. I found that sendmail was set up to deliver mail but I couldn't deliver mail to the box from outside the box. On Google I found that the distro was shipped with the ability to receive mail from external sources turned off. Why? I also set up some shares in Samba and still have the following problem: if I set up a directory - say, /backup - with the same permissions and ownership as /var, I can connect to it from another machine and share the contents, create and update as well as remove.
If I change the entry from /backup to /var then I'm not able to connect to the directory. I guess I have another pre-shipped parameter to change but which one? What I want to do is set up the share to access /var/www/html in order to play with HTML and PHP files. All this works fine on the old system and didn't require changes. I will get to the new version sometime but not until I've solved these and other issues in a standalone system. Just one other point. When I've performed upgrades the process takes hours so I thought it would be easier and quicker to do a new install and copy the relevant config files and data, but now I'm not so sure.
A It looks like you've opted for security when installing the new Fedora. As such, it's been set up to deliver only local mail, which you were able to switch easily enough, and to prevent sensitive directories being shared. While it is possible to alter this so that /var can be shared, you really should reconsider. Blocking the sharing of /var is for a good reason - a lot of sensitive information is stored on /var and it's easy to render a system unbootable with a modicum of malice, incompetence or plain carelessness. The question shouldn't be 'how can I share /var?' but 'do I need to share all of /var?' - to which the answer is no. If you want to access /var/www/html remotely, then share only /var/www/html.
In doing this, you'll avoid the potential risks associated with sharing /var/log or /var/lib but still be able to do what you want. There are also alternatives to using Samba. If both computers run Linux, you could use NFS to mount /var/www/html on the remote computer. If you're using KDE on the editing computer, you could avoid using any form of remote mounting or directory sharing by using KDE's FISH implementation. This uses SSH to communicate with the remote computer, so putting fish://hostname/var/www/html into Konqueror's (or Krusader's) location bar will load the directory's contents into a file manager window, from where you can load files into a KDE-aware editor. Going from very old Fedoras to the latest release is a huge step. Many key components will have changed, so an update is likely to consume more time than the hours required by the package manager when you have to fix other problems.
A fresh install is the best approach, but making a jump of a few years in major components is likely to result in differences in the way things work, as you have discovered.