cd /usr/ports/ports-mgmt/portupgrade
make install clean
It's now possible to update all the software on the system by running the command:
portupgrade -ai

portaudit
which shows the published vulnerabilities affecting the packages installed on your system
As the superuser root, run:
cd /usr/ports/ports-mgmt/portaudit
and then
make install clean

It's now possible to update the vulnerabilities database and audit the installed packages by running the command:
portaudit -Fa

Those are some tricks you may find useful:
to show the differences between the version of the installed packages and the ones of the ports collection currently present on the system, run:
pkg_version -v

to print some informations of a port, like it's dependencies, for example of asterisk, run, in the /usr/ports folder, the command:
make search name=asterisk

to print the dependencies of an installed package, for example of gmake, run:
pkg_info -xr gmake


to print the dependencies of a package, even not installed, for example of proftpd, run, in the folder of it's port, the command:
make pretty-print-build-depends-list
but first you have to run, in the /usr/ports folder, the command:
make index
which, after a while, will build an index with the informations of the packages

And if, for example, the package portupgrade is installed, it's manual can be viewed by running:
man portupgrade