diff --git a/letsencrypt-auto-source/Dockerfile.centos6 b/letsencrypt-auto-source/Dockerfile.centos6
index 8c1a4b353..47eb48f50 100644
--- a/letsencrypt-auto-source/Dockerfile.centos6
+++ b/letsencrypt-auto-source/Dockerfile.centos6
@@ -33,4 +33,5 @@ COPY . /home/lea/certbot/letsencrypt-auto-source
 USER lea
 WORKDIR /home/lea
 
-CMD ["pytest", "-v", "-s", "certbot/letsencrypt-auto-source/tests"]
+RUN sudo chmod +x certbot/letsencrypt-auto-source/tests/centos6_tests.sh
+CMD sudo certbot/letsencrypt-auto-source/tests/centos6_tests.sh
diff --git a/letsencrypt-auto-source/letsencrypt-auto b/letsencrypt-auto-source/letsencrypt-auto
index d3c832541..a184c5e3e 100755
--- a/letsencrypt-auto-source/letsencrypt-auto
+++ b/letsencrypt-auto-source/letsencrypt-auto
@@ -246,15 +246,29 @@ DeprecationBootstrap() {
   fi
 }
 
-
+# Sets LE_PYTHON to Python version string and PYVER to the first two
+# digits of the python version
 DeterminePythonVersion() {
-  for LE_PYTHON in "$LE_PYTHON" python2.7 python27 python2 python; do
-    # Break (while keeping the LE_PYTHON value) if found.
-    $EXISTS "$LE_PYTHON" > /dev/null && break
-  done
+  # Arguments: "NOCRASH" if we shouldn't crash if we don't find a good python
+  if [ -n "$USE_PYTHON_3" ]; then
+    for LE_PYTHON in "$LE_PYTHON" python3; do
+      # Break (while keeping the LE_PYTHON value) if found.
+      $EXISTS "$LE_PYTHON" > /dev/null && break
+    done
+  else
+    for LE_PYTHON in "$LE_PYTHON" python2.7 python27 python2 python; do
+      # Break (while keeping the LE_PYTHON value) if found.
+      $EXISTS "$LE_PYTHON" > /dev/null && break
+    done
+  fi
   if [ "$?" != "0" ]; then
-    error "Cannot find any Pythons; please install one!"
-    exit 1
+    if [ "$1" != "NOCRASH" ]; then
+      error "Cannot find any Pythons; please install one!"
+      exit 1
+    else
+      PYVER=0
+      return 0
+    fi
   fi
   export LE_PYTHON
 
@@ -386,23 +400,19 @@ BootstrapDebCommon() {
   fi
 }
 
-# If new packages are installed by BootstrapRpmCommon below, this version
-# number must be increased.
-BOOTSTRAP_RPM_COMMON_VERSION=1
-
-BootstrapRpmCommon() {
-  # Tested with:
-  #   - Fedora 20, 21, 22, 23 (x64)
-  #   - Centos 7 (x64: on DigitalOcean droplet)
-  #   - CentOS 7 Minimal install in a Hyper-V VM
-  #   - CentOS 6 (EPEL must be installed manually)
+# If new packages are installed by BootstrapRpmCommonBase below, version
+# numbers in rpm_common.sh and rpm_python3.sh must be increased.
 
+# Sets TOOL to the name of the package manager
+# Sets appropriate values for YES_FLAG and QUIET_FLAG based on $ASSUME_YES and $QUIET_FLAG.
+# Enables EPEL if applicable and possible.
+InitializeRPMCommonBase() {
   if type dnf 2>/dev/null
   then
-    tool=dnf
+    TOOL=dnf
   elif type yum 2>/dev/null
   then
-    tool=yum
+    TOOL=yum
 
   else
     error "Neither yum nor dnf found. Aborting bootstrap!"
@@ -410,15 +420,15 @@ BootstrapRpmCommon() {
   fi
 
   if [ "$ASSUME_YES" = 1 ]; then
-    yes_flag="-y"
+    YES_FLAG="-y"
   fi
   if [ "$QUIET" = 1 ]; then
     QUIET_FLAG='--quiet'
   fi
 
-  if ! $tool list *virtualenv >/dev/null 2>&1; then
+  if ! $TOOL list *virtualenv >/dev/null 2>&1; then
     echo "To use Certbot, packages from the EPEL repository need to be installed."
-    if ! $tool list epel-release >/dev/null 2>&1; then
+    if ! $TOOL list epel-release >/dev/null 2>&1; then
       error "Enable the EPEL repository and try running Certbot again."
       exit 1
     fi
@@ -430,11 +440,17 @@ BootstrapRpmCommon() {
       /bin/echo -e "\e[0K\rEnabling the EPEL repository in 1 seconds..."
       sleep 1s
     fi
-    if ! $tool install $yes_flag $QUIET_FLAG epel-release; then
+    if ! $TOOL install $YES_FLAG $QUIET_FLAG epel-release; then
       error "Could not enable EPEL. Aborting bootstrap!"
       exit 1
     fi
   fi
+}
+
+BootstrapRpmCommonBase() {
+  # Arguments: whitespace-delimited python packages to install
+
+  InitializeRPMCommonBase # This call is superfluous in practice
 
   pkgs="
     gcc
@@ -446,10 +462,39 @@ BootstrapRpmCommon() {
     ca-certificates
   "
 
-  # Most RPM distros use the "python" or "python-" naming convention.  Let's try that first.
-  if $tool list python >/dev/null 2>&1; then
+  # Add the python packages
+  pkgs="$pkgs
+    $1
+  "
+
+  if $TOOL list installed "httpd" >/dev/null 2>&1; then
     pkgs="$pkgs
-      python
+      mod_ssl
+    "
+  fi
+
+  if ! $TOOL install $YES_FLAG $QUIET_FLAG $pkgs; then
+    error "Could not install OS dependencies. Aborting bootstrap!"
+    exit 1
+  fi
+}
+
+# If new packages are installed by BootstrapRpmCommon below, this version
+# number must be increased.
+BOOTSTRAP_RPM_COMMON_VERSION=1
+
+BootstrapRpmCommon() {
+  # Tested with:
+  #   - Fedora 20, 21, 22, 23 (x64)
+  #   - Centos 7 (x64: on DigitalOcean droplet)
+  #   - CentOS 7 Minimal install in a Hyper-V VM
+  #   - CentOS 6
+
+  InitializeRPMCommonBase
+
+  # Most RPM distros use the "python" or "python-" naming convention.  Let's try that first.
+  if $TOOL list python >/dev/null 2>&1; then
+    python_pkgs="$python
       python-devel
       python-virtualenv
       python-tools
@@ -457,9 +502,8 @@ BootstrapRpmCommon() {
     "
   # Fedora 26 starts to use the prefix python2 for python2 based packages.
   # this elseif is theoretically for any Fedora over version 26:
-  elif $tool list python2 >/dev/null 2>&1; then
-    pkgs="$pkgs
-      python2
+  elif $TOOL list python2 >/dev/null 2>&1; then
+    python_pkgs="$python2
       python2-libs
       python2-setuptools
       python2-devel
@@ -470,8 +514,7 @@ BootstrapRpmCommon() {
   # Some distros and older versions of current distros use a "python27"
   # instead of the "python" or "python-" naming convention.
   else
-    pkgs="$pkgs
-      python27
+    python_pkgs="$python27
       python27-devel
       python27-virtualenv
       python27-tools
@@ -479,16 +522,31 @@ BootstrapRpmCommon() {
     "
   fi
 
-  if $tool list installed "httpd" >/dev/null 2>&1; then
-    pkgs="$pkgs
-      mod_ssl
-    "
-  fi
+  BootstrapRpmCommonBase "$python_pkgs"
+}
 
-  if ! $tool install $yes_flag $QUIET_FLAG $pkgs; then
-    error "Could not install OS dependencies. Aborting bootstrap!"
+# If new packages are installed by BootstrapRpmPython3 below, this version
+# number must be increased.
+BOOTSTRAP_RPM_PYTHON3_VERSION=1
+
+BootstrapRpmPython3() {
+  # Tested with:
+  #   - CentOS 6
+
+  InitializeRPMCommonBase
+
+  # EPEL uses python34
+  if $TOOL list python34 >/dev/null 2>&1; then
+    python_pkgs="python34
+      python34-devel
+      python34-tools
+    "
+  else
+    error "No supported Python package available to install. Aborting bootstrap!"
     exit 1
   fi
+
+  BootstrapRpmCommonBase "$python_pkgs"
 }
 
 # If new packages are installed by BootstrapSuseCommon below, this version
@@ -717,11 +775,24 @@ elif [ -f /etc/mageia-release ]; then
   }
   BOOTSTRAP_VERSION="BootstrapMageiaCommon $BOOTSTRAP_MAGEIA_COMMON_VERSION"
 elif [ -f /etc/redhat-release ]; then
-  Bootstrap() {
-    BootstrapMessage "RedHat-based OSes"
-    BootstrapRpmCommon
-  }
-  BOOTSTRAP_VERSION="BootstrapRpmCommon $BOOTSTRAP_RPM_COMMON_VERSION"
+  prev_le_python="$LE_PYTHON"
+  unset LE_PYTHON
+  DeterminePythonVersion "NOCRASH"
+  if [ "$PYVER" -eq 26 ]; then
+    Bootstrap() {
+      BootstrapMessage "RedHat-based OSes that will use Python3"
+      BootstrapRpmPython3
+    }
+    USE_PYTHON_3=1
+    BOOTSTRAP_VERSION="BootstrapRpmPython3 $BOOTSTRAP_RPM_PYTHON3_VERSION"
+  else
+    Bootstrap() {
+      BootstrapMessage "RedHat-based OSes"
+      BootstrapRpmCommon
+    }
+    BOOTSTRAP_VERSION="BootstrapRpmCommon $BOOTSTRAP_RPM_COMMON_VERSION"
+  fi
+  export LE_PYTHON="$prev_le_python"
 elif [ -f /etc/os-release ] && `grep -q openSUSE /etc/os-release` ; then
   Bootstrap() {
     BootstrapMessage "openSUSE-based OSes"
@@ -869,10 +940,18 @@ if [ "$1" = "--le-auto-phase2" ]; then
     say "Creating virtual environment..."
     DeterminePythonVersion
     rm -rf "$VENV_PATH"
-    if [ "$VERBOSE" = 1 ]; then
-      virtualenv --no-site-packages --python "$LE_PYTHON" "$VENV_PATH"
+    if [ "$PYVER" -le 27 ]; then
+      if [ "$VERBOSE" = 1 ]; then
+        virtualenv --no-site-packages --python "$LE_PYTHON" "$VENV_PATH"
+      else
+        virtualenv --no-site-packages --python "$LE_PYTHON" "$VENV_PATH" > /dev/null
+      fi
     else
-      virtualenv --no-site-packages --python "$LE_PYTHON" "$VENV_PATH" > /dev/null
+      if [ "$VERBOSE" = 1 ]; then
+        "$LE_PYTHON" -m venv "$VENV_PATH"
+      else
+        "$LE_PYTHON" -m venv "$VENV_PATH" > /dev/null
+      fi
     fi
 
     if [ -n "$BOOTSTRAP_VERSION" ]; then
@@ -1367,17 +1446,22 @@ On failure, return non-zero.
 
 """
 
-from __future__ import print_function
+from __future__ import print_function, unicode_literals
 
 from distutils.version import LooseVersion
 from json import loads
 from os import devnull, environ
 from os.path import dirname, join
 import re
+import ssl
 from subprocess import check_call, CalledProcessError
 from sys import argv, exit
-from urllib2 import build_opener, HTTPHandler, HTTPSHandler
-from urllib2 import HTTPError, URLError
+try:
+    from urllib2 import build_opener, HTTPHandler, HTTPSHandler
+    from urllib2 import HTTPError, URLError
+except ImportError:
+    from urllib.request import build_opener, HTTPHandler, HTTPSHandler
+    from urllib.error import HTTPError, URLError
 
 PUBLIC_KEY = environ.get('LE_AUTO_PUBLIC_KEY', """-----BEGIN PUBLIC KEY-----
 MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA6MR8W/galdxnpGqBsYbq
@@ -1399,8 +1483,11 @@ class HttpsGetter(object):
     def __init__(self):
         """Build an HTTPS opener."""
         # Based on pip 1.4.1's URLOpener
-        # This verifies certs on only Python >=2.7.9.
-        self._opener = build_opener(HTTPSHandler())
+        # This verifies certs on only Python >=2.7.9, and when NO_CERT_VERIFY isn't set.
+        if environ.get('NO_CERT_VERIFY') == '1' and hasattr(ssl, 'SSLContext'):
+            self._opener = build_opener(HTTPSHandler(context=create_CERT_NONE_context()))
+        else:
+            self._opener = build_opener(HTTPSHandler())
         # Strip out HTTPHandler to prevent MITM spoof:
         for handler in self._opener.handlers:
             if isinstance(handler, HTTPHandler):
@@ -1422,7 +1509,7 @@ class HttpsGetter(object):
 
 def write(contents, dir, filename):
     """Write something to a file in a certain directory."""
-    with open(join(dir, filename), 'w') as file:
+    with open(join(dir, filename), 'wb') as file:
         file.write(contents)
 
 
@@ -1430,13 +1517,13 @@ def latest_stable_version(get):
     """Return the latest stable release of letsencrypt."""
     metadata = loads(get(
         environ.get('LE_AUTO_JSON_URL',
-                    'https://pypi.python.org/pypi/certbot/json')))
+                    'https://pypi.python.org/pypi/certbot/json')).decode('UTF-8'))
     # metadata['info']['version'] actually returns the latest of any kind of
     # release release, contrary to https://wiki.python.org/moin/PyPIJSON.
     # The regex is a sufficient regex for picking out prereleases for most
     # packages, LE included.
     return str(max(LooseVersion(r) for r
-                   in metadata['releases'].iterkeys()
+                   in iter(metadata['releases'].keys())
                    if re.match('^[0-9.]+$', r)))
 
 
@@ -1453,7 +1540,7 @@ def verified_new_le_auto(get, tag, temp_dir):
         'letsencrypt-auto-source/') % tag
     write(get(le_auto_dir + 'letsencrypt-auto'), temp_dir, 'letsencrypt-auto')
     write(get(le_auto_dir + 'letsencrypt-auto.sig'), temp_dir, 'letsencrypt-auto.sig')
-    write(PUBLIC_KEY, temp_dir, 'public_key.pem')
+    write(PUBLIC_KEY.encode('UTF-8'), temp_dir, 'public_key.pem')
     try:
         with open(devnull, 'w') as dev_null:
             check_call(['openssl', 'dgst', '-sha256', '-verify',
@@ -1468,6 +1555,14 @@ def verified_new_le_auto(get, tag, temp_dir):
                             "certbot-auto.", exc)
 
 
+def create_CERT_NONE_context():
+    """Create a SSLContext object to not check hostname."""
+    # PROTOCOL_TLS isn't available before 2.7.13 but this code is for 2.7.9+, so use this.
+    context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+    context.verify_mode = ssl.CERT_NONE
+    return context
+
+
 def main():
     get = HttpsGetter().get
     flag = argv[1]
diff --git a/letsencrypt-auto-source/letsencrypt-auto.template b/letsencrypt-auto-source/letsencrypt-auto.template
index 288745403..c8c5ca5c5 100755
--- a/letsencrypt-auto-source/letsencrypt-auto.template
+++ b/letsencrypt-auto-source/letsencrypt-auto.template
@@ -246,15 +246,29 @@ DeprecationBootstrap() {
   fi
 }
 
-
+# Sets LE_PYTHON to Python version string and PYVER to the first two
+# digits of the python version
 DeterminePythonVersion() {
-  for LE_PYTHON in "$LE_PYTHON" python2.7 python27 python2 python; do
-    # Break (while keeping the LE_PYTHON value) if found.
-    $EXISTS "$LE_PYTHON" > /dev/null && break
-  done
+  # Arguments: "NOCRASH" if we shouldn't crash if we don't find a good python
+  if [ -n "$USE_PYTHON_3" ]; then
+    for LE_PYTHON in "$LE_PYTHON" python3; do
+      # Break (while keeping the LE_PYTHON value) if found.
+      $EXISTS "$LE_PYTHON" > /dev/null && break
+    done
+  else
+    for LE_PYTHON in "$LE_PYTHON" python2.7 python27 python2 python; do
+      # Break (while keeping the LE_PYTHON value) if found.
+      $EXISTS "$LE_PYTHON" > /dev/null && break
+    done
+  fi
   if [ "$?" != "0" ]; then
-    error "Cannot find any Pythons; please install one!"
-    exit 1
+    if [ "$1" != "NOCRASH" ]; then
+      error "Cannot find any Pythons; please install one!"
+      exit 1
+    else
+      PYVER=0
+      return 0
+    fi
   fi
   export LE_PYTHON
 
@@ -267,7 +281,9 @@ DeterminePythonVersion() {
 }
 
 {{ bootstrappers/deb_common.sh }}
+{{ bootstrappers/rpm_common_base.sh }}
 {{ bootstrappers/rpm_common.sh }}
+{{ bootstrappers/rpm_python3.sh }}
 {{ bootstrappers/suse_common.sh }}
 {{ bootstrappers/arch_common.sh }}
 {{ bootstrappers/gentoo_common.sh }}
@@ -298,11 +314,24 @@ elif [ -f /etc/mageia-release ]; then
   }
   BOOTSTRAP_VERSION="BootstrapMageiaCommon $BOOTSTRAP_MAGEIA_COMMON_VERSION"
 elif [ -f /etc/redhat-release ]; then
-  Bootstrap() {
-    BootstrapMessage "RedHat-based OSes"
-    BootstrapRpmCommon
-  }
-  BOOTSTRAP_VERSION="BootstrapRpmCommon $BOOTSTRAP_RPM_COMMON_VERSION"
+  prev_le_python="$LE_PYTHON"
+  unset LE_PYTHON
+  DeterminePythonVersion "NOCRASH"
+  if [ "$PYVER" -eq 26 ]; then
+    Bootstrap() {
+      BootstrapMessage "RedHat-based OSes that will use Python3"
+      BootstrapRpmPython3
+    }
+    USE_PYTHON_3=1
+    BOOTSTRAP_VERSION="BootstrapRpmPython3 $BOOTSTRAP_RPM_PYTHON3_VERSION"
+  else
+    Bootstrap() {
+      BootstrapMessage "RedHat-based OSes"
+      BootstrapRpmCommon
+    }
+    BOOTSTRAP_VERSION="BootstrapRpmCommon $BOOTSTRAP_RPM_COMMON_VERSION"
+  fi
+  export LE_PYTHON="$prev_le_python"
 elif [ -f /etc/os-release ] && `grep -q openSUSE /etc/os-release` ; then
   Bootstrap() {
     BootstrapMessage "openSUSE-based OSes"
@@ -450,10 +479,18 @@ if [ "$1" = "--le-auto-phase2" ]; then
     say "Creating virtual environment..."
     DeterminePythonVersion
     rm -rf "$VENV_PATH"
-    if [ "$VERBOSE" = 1 ]; then
-      virtualenv --no-site-packages --python "$LE_PYTHON" "$VENV_PATH"
+    if [ "$PYVER" -le 27 ]; then
+      if [ "$VERBOSE" = 1 ]; then
+        virtualenv --no-site-packages --python "$LE_PYTHON" "$VENV_PATH"
+      else
+        virtualenv --no-site-packages --python "$LE_PYTHON" "$VENV_PATH" > /dev/null
+      fi
     else
-      virtualenv --no-site-packages --python "$LE_PYTHON" "$VENV_PATH" > /dev/null
+      if [ "$VERBOSE" = 1 ]; then
+        "$LE_PYTHON" -m venv "$VENV_PATH"
+      else
+        "$LE_PYTHON" -m venv "$VENV_PATH" > /dev/null
+      fi
     fi
 
     if [ -n "$BOOTSTRAP_VERSION" ]; then
diff --git a/letsencrypt-auto-source/pieces/bootstrappers/rpm_common.sh b/letsencrypt-auto-source/pieces/bootstrappers/rpm_common.sh
index 5b120a9e6..80d55a393 100755
--- a/letsencrypt-auto-source/pieces/bootstrappers/rpm_common.sh
+++ b/letsencrypt-auto-source/pieces/bootstrappers/rpm_common.sh
@@ -7,61 +7,13 @@ BootstrapRpmCommon() {
   #   - Fedora 20, 21, 22, 23 (x64)
   #   - Centos 7 (x64: on DigitalOcean droplet)
   #   - CentOS 7 Minimal install in a Hyper-V VM
-  #   - CentOS 6 (EPEL must be installed manually)
+  #   - CentOS 6
 
-  if type dnf 2>/dev/null
-  then
-    tool=dnf
-  elif type yum 2>/dev/null
-  then
-    tool=yum
-
-  else
-    error "Neither yum nor dnf found. Aborting bootstrap!"
-    exit 1
-  fi
-
-  if [ "$ASSUME_YES" = 1 ]; then
-    yes_flag="-y"
-  fi
-  if [ "$QUIET" = 1 ]; then
-    QUIET_FLAG='--quiet'
-  fi
-
-  if ! $tool list *virtualenv >/dev/null 2>&1; then
-    echo "To use Certbot, packages from the EPEL repository need to be installed."
-    if ! $tool list epel-release >/dev/null 2>&1; then
-      error "Enable the EPEL repository and try running Certbot again."
-      exit 1
-    fi
-    if [ "$ASSUME_YES" = 1 ]; then
-      /bin/echo -n "Enabling the EPEL repository in 3 seconds..."
-      sleep 1s
-      /bin/echo -ne "\e[0K\rEnabling the EPEL repository in 2 seconds..."
-      sleep 1s
-      /bin/echo -e "\e[0K\rEnabling the EPEL repository in 1 seconds..."
-      sleep 1s
-    fi
-    if ! $tool install $yes_flag $QUIET_FLAG epel-release; then
-      error "Could not enable EPEL. Aborting bootstrap!"
-      exit 1
-    fi
-  fi
-
-  pkgs="
-    gcc
-    augeas-libs
-    openssl
-    openssl-devel
-    libffi-devel
-    redhat-rpm-config
-    ca-certificates
-  "
+  InitializeRPMCommonBase
 
   # Most RPM distros use the "python" or "python-" naming convention.  Let's try that first.
-  if $tool list python >/dev/null 2>&1; then
-    pkgs="$pkgs
-      python
+  if $TOOL list python >/dev/null 2>&1; then
+    python_pkgs="$python
       python-devel
       python-virtualenv
       python-tools
@@ -69,9 +21,8 @@ BootstrapRpmCommon() {
     "
   # Fedora 26 starts to use the prefix python2 for python2 based packages.
   # this elseif is theoretically for any Fedora over version 26:
-  elif $tool list python2 >/dev/null 2>&1; then
-    pkgs="$pkgs
-      python2
+  elif $TOOL list python2 >/dev/null 2>&1; then
+    python_pkgs="$python2
       python2-libs
       python2-setuptools
       python2-devel
@@ -82,8 +33,7 @@ BootstrapRpmCommon() {
   # Some distros and older versions of current distros use a "python27"
   # instead of the "python" or "python-" naming convention.
   else
-    pkgs="$pkgs
-      python27
+    python_pkgs="$python27
       python27-devel
       python27-virtualenv
       python27-tools
@@ -91,14 +41,5 @@ BootstrapRpmCommon() {
     "
   fi
 
-  if $tool list installed "httpd" >/dev/null 2>&1; then
-    pkgs="$pkgs
-      mod_ssl
-    "
-  fi
-
-  if ! $tool install $yes_flag $QUIET_FLAG $pkgs; then
-    error "Could not install OS dependencies. Aborting bootstrap!"
-    exit 1
-  fi
+  BootstrapRpmCommonBase "$python_pkgs"
 }
diff --git a/letsencrypt-auto-source/pieces/bootstrappers/rpm_common_base.sh b/letsencrypt-auto-source/pieces/bootstrappers/rpm_common_base.sh
new file mode 100644
index 000000000..d7a9f3133
--- /dev/null
+++ b/letsencrypt-auto-source/pieces/bootstrappers/rpm_common_base.sh
@@ -0,0 +1,78 @@
+# If new packages are installed by BootstrapRpmCommonBase below, version
+# numbers in rpm_common.sh and rpm_python3.sh must be increased.
+
+# Sets TOOL to the name of the package manager
+# Sets appropriate values for YES_FLAG and QUIET_FLAG based on $ASSUME_YES and $QUIET_FLAG.
+# Enables EPEL if applicable and possible.
+InitializeRPMCommonBase() {
+  if type dnf 2>/dev/null
+  then
+    TOOL=dnf
+  elif type yum 2>/dev/null
+  then
+    TOOL=yum
+
+  else
+    error "Neither yum nor dnf found. Aborting bootstrap!"
+    exit 1
+  fi
+
+  if [ "$ASSUME_YES" = 1 ]; then
+    YES_FLAG="-y"
+  fi
+  if [ "$QUIET" = 1 ]; then
+    QUIET_FLAG='--quiet'
+  fi
+
+  if ! $TOOL list *virtualenv >/dev/null 2>&1; then
+    echo "To use Certbot, packages from the EPEL repository need to be installed."
+    if ! $TOOL list epel-release >/dev/null 2>&1; then
+      error "Enable the EPEL repository and try running Certbot again."
+      exit 1
+    fi
+    if [ "$ASSUME_YES" = 1 ]; then
+      /bin/echo -n "Enabling the EPEL repository in 3 seconds..."
+      sleep 1s
+      /bin/echo -ne "\e[0K\rEnabling the EPEL repository in 2 seconds..."
+      sleep 1s
+      /bin/echo -e "\e[0K\rEnabling the EPEL repository in 1 seconds..."
+      sleep 1s
+    fi
+    if ! $TOOL install $YES_FLAG $QUIET_FLAG epel-release; then
+      error "Could not enable EPEL. Aborting bootstrap!"
+      exit 1
+    fi
+  fi
+}
+
+BootstrapRpmCommonBase() {
+  # Arguments: whitespace-delimited python packages to install
+
+  InitializeRPMCommonBase # This call is superfluous in practice
+
+  pkgs="
+    gcc
+    augeas-libs
+    openssl
+    openssl-devel
+    libffi-devel
+    redhat-rpm-config
+    ca-certificates
+  "
+
+  # Add the python packages
+  pkgs="$pkgs
+    $1
+  "
+
+  if $TOOL list installed "httpd" >/dev/null 2>&1; then
+    pkgs="$pkgs
+      mod_ssl
+    "
+  fi
+
+  if ! $TOOL install $YES_FLAG $QUIET_FLAG $pkgs; then
+    error "Could not install OS dependencies. Aborting bootstrap!"
+    exit 1
+  fi
+}
diff --git a/letsencrypt-auto-source/pieces/bootstrappers/rpm_python3.sh b/letsencrypt-auto-source/pieces/bootstrappers/rpm_python3.sh
new file mode 100644
index 000000000..b011a7235
--- /dev/null
+++ b/letsencrypt-auto-source/pieces/bootstrappers/rpm_python3.sh
@@ -0,0 +1,23 @@
+# If new packages are installed by BootstrapRpmPython3 below, this version
+# number must be increased.
+BOOTSTRAP_RPM_PYTHON3_VERSION=1
+
+BootstrapRpmPython3() {
+  # Tested with:
+  #   - CentOS 6
+
+  InitializeRPMCommonBase
+
+  # EPEL uses python34
+  if $TOOL list python34 >/dev/null 2>&1; then
+    python_pkgs="python34
+      python34-devel
+      python34-tools
+    "
+  else
+    error "No supported Python package available to install. Aborting bootstrap!"
+    exit 1
+  fi
+
+  BootstrapRpmCommonBase "$python_pkgs"
+}
diff --git a/letsencrypt-auto-source/pieces/fetch.py b/letsencrypt-auto-source/pieces/fetch.py
index 8f34351c9..ae72a299b 100644
--- a/letsencrypt-auto-source/pieces/fetch.py
+++ b/letsencrypt-auto-source/pieces/fetch.py
@@ -11,17 +11,22 @@ On failure, return non-zero.
 
 """
 
-from __future__ import print_function
+from __future__ import print_function, unicode_literals
 
 from distutils.version import LooseVersion
 from json import loads
 from os import devnull, environ
 from os.path import dirname, join
 import re
+import ssl
 from subprocess import check_call, CalledProcessError
 from sys import argv, exit
-from urllib2 import build_opener, HTTPHandler, HTTPSHandler
-from urllib2 import HTTPError, URLError
+try:
+    from urllib2 import build_opener, HTTPHandler, HTTPSHandler
+    from urllib2 import HTTPError, URLError
+except ImportError:
+    from urllib.request import build_opener, HTTPHandler, HTTPSHandler
+    from urllib.error import HTTPError, URLError
 
 PUBLIC_KEY = environ.get('LE_AUTO_PUBLIC_KEY', """-----BEGIN PUBLIC KEY-----
 MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA6MR8W/galdxnpGqBsYbq
@@ -43,8 +48,11 @@ class HttpsGetter(object):
     def __init__(self):
         """Build an HTTPS opener."""
         # Based on pip 1.4.1's URLOpener
-        # This verifies certs on only Python >=2.7.9.
-        self._opener = build_opener(HTTPSHandler())
+        # This verifies certs on only Python >=2.7.9, and when NO_CERT_VERIFY isn't set.
+        if environ.get('NO_CERT_VERIFY') == '1' and hasattr(ssl, 'SSLContext'):
+            self._opener = build_opener(HTTPSHandler(context=create_CERT_NONE_context()))
+        else:
+            self._opener = build_opener(HTTPSHandler())
         # Strip out HTTPHandler to prevent MITM spoof:
         for handler in self._opener.handlers:
             if isinstance(handler, HTTPHandler):
@@ -66,7 +74,7 @@ class HttpsGetter(object):
 
 def write(contents, dir, filename):
     """Write something to a file in a certain directory."""
-    with open(join(dir, filename), 'w') as file:
+    with open(join(dir, filename), 'wb') as file:
         file.write(contents)
 
 
@@ -74,13 +82,13 @@ def latest_stable_version(get):
     """Return the latest stable release of letsencrypt."""
     metadata = loads(get(
         environ.get('LE_AUTO_JSON_URL',
-                    'https://pypi.python.org/pypi/certbot/json')))
+                    'https://pypi.python.org/pypi/certbot/json')).decode('UTF-8'))
     # metadata['info']['version'] actually returns the latest of any kind of
     # release release, contrary to https://wiki.python.org/moin/PyPIJSON.
     # The regex is a sufficient regex for picking out prereleases for most
     # packages, LE included.
     return str(max(LooseVersion(r) for r
-                   in metadata['releases'].iterkeys()
+                   in iter(metadata['releases'].keys())
                    if re.match('^[0-9.]+$', r)))
 
 
@@ -97,7 +105,7 @@ def verified_new_le_auto(get, tag, temp_dir):
         'letsencrypt-auto-source/') % tag
     write(get(le_auto_dir + 'letsencrypt-auto'), temp_dir, 'letsencrypt-auto')
     write(get(le_auto_dir + 'letsencrypt-auto.sig'), temp_dir, 'letsencrypt-auto.sig')
-    write(PUBLIC_KEY, temp_dir, 'public_key.pem')
+    write(PUBLIC_KEY.encode('UTF-8'), temp_dir, 'public_key.pem')
     try:
         with open(devnull, 'w') as dev_null:
             check_call(['openssl', 'dgst', '-sha256', '-verify',
@@ -112,6 +120,14 @@ def verified_new_le_auto(get, tag, temp_dir):
                             "certbot-auto.", exc)
 
 
+def create_CERT_NONE_context():
+    """Create a SSLContext object to not check hostname."""
+    # PROTOCOL_TLS isn't available before 2.7.13 but this code is for 2.7.9+, so use this.
+    context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+    context.verify_mode = ssl.CERT_NONE
+    return context
+
+
 def main():
     get = HttpsGetter().get
     flag = argv[1]
diff --git a/letsencrypt-auto-source/tests/auto_test.py b/letsencrypt-auto-source/tests/auto_test.py
index 156466c82..d187452a1 100644
--- a/letsencrypt-auto-source/tests/auto_test.py
+++ b/letsencrypt-auto-source/tests/auto_test.py
@@ -202,6 +202,7 @@ LsIVPBuy9IcgHidUQ96hJnoPsDCWsHwX62495QKEarauyKQrJzFes0EY95orDM47
 Z5o/NDiQB11m91yNB0MmPYY9QSbnOA9j7IaaC97AwRLuwXY+/R2ablTcxurWou68
 iQIDAQAB
 -----END PUBLIC KEY-----""",
+             NO_CERT_VERIFY='1',
              **kwargs)
     env.update(d)
     return out_and_err(
@@ -349,6 +350,7 @@ class AutoTests(TestCase):
                     self.assertTrue("Couldn't verify signature of downloaded "
                                     "certbot-auto." in exc.output)
                 else:
+                    print(out)
                     self.fail('Signature check on certbot-auto erroneously passed.')
 
     def test_pip_failure(self):
diff --git a/letsencrypt-auto-source/tests/centos6_tests.sh b/letsencrypt-auto-source/tests/centos6_tests.sh
new file mode 100644
index 000000000..e3ebbaec5
--- /dev/null
+++ b/letsencrypt-auto-source/tests/centos6_tests.sh
@@ -0,0 +1,65 @@
+#!/bin/bash
+# Start by making sure your system is up-to-date:
+yum update > /dev/null
+yum install -y centos-release-scl > /dev/null
+yum install -y python27 > /dev/null 2> /dev/null
+
+# we're going to modify env variables, so do this in a subshell
+(
+source /opt/rh/python27/enable
+
+# ensure python 3 isn't installed
+python3 --version 2> /dev/null
+RESULT=$?
+if [ $RESULT -eq 0 ]; then
+  error "Python3 is already installed."
+  exit 1
+fi
+
+# ensure python2.7 is available
+python2.7 --version 2> /dev/null
+RESULT=$?
+if [ $RESULT -ne 0 ]; then
+  error "Python3 is not available."
+  exit 1
+fi
+
+# bootstrap, but don't install python 3.
+certbot/letsencrypt-auto-source/letsencrypt-auto --no-self-upgrade -n > /dev/null 2> /dev/null
+
+# ensure python 3 isn't installed
+python3 --version 2> /dev/null
+RESULT=$?
+if [ $RESULT -eq 0 ]; then
+  error "letsencrypt-auto installed Python3 even though Python2.7 is present."
+  exit 1
+fi
+
+echo ""
+echo "PASSED: Did not upgrade to Python3 when Python2.7 is present."
+)
+
+# ensure python2.7 isn't available
+python2.7 --version 2> /dev/null
+RESULT=$?
+if [ $RESULT -eq 0 ]; then
+  error "Python2.7 is still available."
+  exit 1
+fi
+
+# bootstrap, this time installing python3
+certbot/letsencrypt-auto-source/letsencrypt-auto --no-self-upgrade -n > /dev/null 2> /dev/null
+
+# ensure python 3 is installed
+python3 --version > /dev/null
+RESULT=$?
+if [ $RESULT -ne 0 ]; then
+  error "letsencrypt-auto failed to install Python3 when only Python2.6 is present."
+  exit 1
+fi
+
+echo "PASSED: Successfully upgraded to Python3 when only Python2.6 is present."
+echo ""
+
+# test using python3
+pytest -v -s certbot/letsencrypt-auto-source/tests