Add a vagrant ssh-config data to ".ssh/config" file. Require plugin: vagrant-global-status

add_ssh_config.sh

#!/bin/bash

SSH=$HOME/.ssh
[ ! -f $SSH/config ] && touch $SSH/config
[ -f $SSH/config ] && [ ! -f $SSH/config.orig ] && mv $SSH/config{,.orig}
rm -f $SSH/config.vagrant
touch $SSH/config.vagrant
for dir in $(vagrant global-status | grep $HOME)
do
    pushd $dir > /dev/null
    vagrant ssh-config --host $(basename $dir) >> $SSH/config.vagrant
    popd > /dev/null
done
cat $SSH/config.orig $SSH/config.vagrant > $SSH/config

Another approach within Vagrant directory :)

#!/usr/bin/env bash
# This file can generate SSH configuration in `~/.ssh/config` file for current Vagrant instance.
# Please put this file in the same directory of Vagrant file.
# Using:
#   # by default, base hostname will be taken from config.vm.hostname or directory name
#   $ vagrant_ssh_config.sh
#   # The same but with additional aliases
#   $ vagrant_ssh_config.sh host.alias.1 host.alias.2

SSH=$HOME/.ssh
if [ -f ${SSH}/config ] && [ ! -f ${SSH}/config.orig ]; then
    mv ${SSH}/config{,.orig} && \
    echo 'Exists ~/ssh/config file stored in ~/.ssh/config.orig. Please use it for further custom changes.'
elif [ ! -f ${SSH}/config ]; then
    touch ${SSH}/config
fi

dir=$(pwd)

# Define hostname
# If there is no declaration config.vm.hostname in Vagrant file, it will use directory name
hostname=$(cat ${dir}/Vagrantfile | grep 'config.vm.hostname = ' | cut -d '=' -f 2 | tr -d "'"'"' | xargs)
[ -z "${hostname}" ] && hostname=$(basename ${dir})
# add aliases from arguments list
hostname+=" $@"

pushd ${dir} > /dev/null
vagrant ssh-config --host "${hostname}" > ${SSH}/config.$(echo ${dir} | tr '/\\' '-').vagrant
popd > /dev/null

cat ${SSH}/config.orig ${SSH}/config.*.vagrant > ${SSH}/config

It's allowed to add some hostname aliases.
vagrant_ssh_config.sh host.alias.1 host.alias.2