Adding configuration to build CentOS 6.7 box.

centos-6.7-x86_64.json

+{
+  "builders": [
+    {
+      "name": "centos-6.7-x86_64",
+      "type": "virtualbox-iso",
+      "boot_command": [
+        "<tab> text ks=http://{{ .HTTPIP }}:{{ .HTTPPort }}/centos/centos-6.7-ks.cfg<enter><wait>"
+      ],
+      "boot_wait": "10s",
+      "disk_size": 40960,
+      "guest_additions_path": "VBoxGuestAdditions_{{ .Version }}.iso",
+      "guest_os_type": "RedHat_64",
+      "http_directory": "http",
+      "iso_checksum": "9d3fec5897be6b3fed4d3dda80b8fa7bb62c616bbfd4bdcd27295ca9b764f498",
+      "iso_checksum_type": "sha256",
+      "iso_url": "http://mirrors.kernel.org/centos/6.7/isos/x86_64/CentOS-6.7-x86_64-minimal.iso",
+      "shutdown_command": "echo 'vagrant'|sudo -S /sbin/halt -h -p",
+      "ssh_password": "vagrant",
+      "ssh_port": 22,
+      "ssh_username": "vagrant",
+      "ssh_wait_timeout": "10000s",
+      "vboxmanage": [
+        [ "modifyvm", "{{ .Name }}", "--memory", "512" ],
+        [ "modifyvm", "{{ .Name }}", "--cpus", "1" ]
+      ],
+      "virtualbox_version_file": ".vbox_version"
+    }
+  ],
+  "provisioners": [
+    {
+      "execute_command": "echo 'vagrant' | {{ .Vars }} sudo -S -E bash '{{ .Path }}'",
+      "scripts": [
+        "scripts/common/build_information.sh",
+        "scripts/centos/yum_config.sh",
+        "scripts/common/sshd.sh",
+        "scripts/common/vagrant.sh",
+        "scripts/centos/update.sh",
+        "scripts/centos/cleanup.sh",
+        "scripts/common/minimize.sh"
+      ],
+      "type": "shell"
+    }
+  ],
+  "post-processors": [
+    {
+      "type": "vagrant",
+      "output": "build/vagrant/{{ .Provider }}/centos-6.7-x86_64.box"
+    }
+  ]
+}

http/centos/centos-6.7-ks.cfg

+install
+cdrom
+lang en_US.UTF-8
+keyboard us
+network --bootproto=dhcp
+rootpw --iscrypted $1$damlkd,f$UC/u5pUts5QiU3ow.CSso/
+firewall --disabled
+authconfig --enableshadow --passalgo=sha512
+selinux --disabled
+timezone UTC
+bootloader --location=mbr
+text
+skipx
+zerombr
+clearpart --all --initlabel
+autopart
+auth  --useshadow  --enablemd5
+firstboot --disabled
+reboot
+
+%packages --ignoremissing
+@Base
+@Core
+@Development Tools
+openssl-devel
+readline-devel
+zlib-devel
+kernel-devel
+
+%post
+# update root certs
+wget -O/etc/pki/tls/certs/ca-bundle.crt http://curl.haxx.se/ca/cacert.pem
+# vagrant
+groupadd vagrant -g 999
+useradd vagrant -g vagrant -G wheel -u 900
+echo "vagrant" | passwd --stdin vagrant
+# sudo
+echo "vagrant        ALL=(ALL)       NOPASSWD: ALL" >> /etc/sudoers
+sed -i "s/^.*requiretty/#Defaults requiretty/" /etc/sudoers