diff --git a/certbot_haproxy/constants.py b/certbot_haproxy/constants.py
index 0b9be17..0570a65 100644
--- a/certbot_haproxy/constants.py
+++ b/certbot_haproxy/constants.py
@@ -10,6 +10,7 @@
   - Ubuntu Vivid (15.04)
   - Ubuntu Wily (15.10)
   - Ubuntu Xenial (16.04)
+  - CentOS (7)
 
 You can define new lists below following the instructions hereafter, please
 consider making a pull-request when you do so, so others may benefit of your
@@ -57,8 +58,8 @@
 from certbot_haproxy.util import MemoiseNoArgs
 
 RE_HAPROXY_DOMAIN_ACL = re.compile(
-    r'\s*acl (?P<name>[0-9a-z_\-.]+) '
-    r'hdr\(host\) -i '
+    r'\s*acl\s+(?P<name>[0-9a-z_\-.]+)\s+'
+    r'(?:hdr\(host\)|req\.ssl_sni)\s+-i\s+'
     r'(?P<domain>'  # Start group "domain"
     r'(?:[0-9-a-z](?:[a-z0-9-]{0,61}[a-z0-9]\.)+)'  # (sub-)domain parts
     r'(?:[0-9-a-z](?:[a-z0-9-]{0,61}[a-z0-9]))'  # TLD part
@@ -87,6 +88,29 @@
     crt_directory='/opt/certbot/haproxy_fullchains',
 )
 
+CLI_DEFAULTS_RHEL_BASED_SYSTEMD_OS = dict(
+    service_manager='systemctl',
+    version_cmd=['/usr/sbin/haproxy', '-v'],
+    restart_cmd=['sudo', 'systemctl', 'restart', 'haproxy'],
+    # Needs the config file as an argument:
+    conftest_cmd=['/usr/sbin/haproxy', '-c', '-f'],
+    haproxy_config='/etc/haproxy/haproxy.cfg',
+    # Needs to be writeable by the user that will run certbot
+    crt_directory='/opt/certbot/haproxy_fullchains',
+)
+
+CLI_DEFAULTS_GENTOO_BASED_SYSTEMD_OS = dict(
+    service_manager='/sbin/service',
+    version_cmd=['/usr/bin/haproxy', '-v'],
+    restart_cmd=['sudo', '/etc/init.d/haproxy', 'restart'],
+    # Needs the config file as an argument:
+    conftest_cmd=['/usr/bin/haproxy', '-c', '-f'],
+    haproxy_config='/etc/haproxy/haproxy.cfg',
+    # Needs to be writeable by the user that will run certbot
+    crt_directory='/opt/certbot/haproxy_fullchains',
+)
+
+
 CLI_DEFAULTS = {
     "debian": {
         '_min_version': '7',
@@ -102,7 +126,16 @@
         '15.04': CLI_DEFAULTS_DEBIAN_BASED_SYSTEMD_OS,
         '15.10': CLI_DEFAULTS_DEBIAN_BASED_SYSTEMD_OS,
         '16.04': CLI_DEFAULTS_DEBIAN_BASED_SYSTEMD_OS
-    }
+    },
+    "centos": {
+        '_min_version': '7',
+        '7': CLI_DEFAULTS_RHEL_BASED_SYSTEMD_OS
+    },
+    "gentoo": {
+        '_min_version': '0',
+        '_max_version': '999999',
+        '': CLI_DEFAULTS_GENTOO_BASED_SYSTEMD_OS
+    },
 }
 
 logger = logging.getLogger(__name__)  # pylint:disable=invalid-name
diff --git a/certbot_haproxy/installer.py b/certbot_haproxy/installer.py
index 28c5fa4..fab601e 100644
--- a/certbot_haproxy/installer.py
+++ b/certbot_haproxy/installer.py
@@ -247,7 +247,7 @@ def prepare():
 
         # Check that a supported version of HAProxy is installed.
         version_cmd = constants.os_constant("version_cmd")
-        output = subprocess.check_output(version_cmd)
+        output = subprocess.check_output(version_cmd).decode('utf-8')
         matches = re.match(
             r'HA-Proxy version'
             r' (?P<version>[0-9]{1,4}\.[0-9]{1,4}\.[0-9a-z]{1,10}).*',
@@ -472,7 +472,8 @@ def save(self, title=None, temporary=False):
             path = os.path.dirname(os.path.abspath(filepath))
             if not os.path.exists(path):
                 os.makedirs(path)
-
+            if isinstance(contents, bytes):
+                contents = contents.decode('utf-8')
             with open(filepath, 'w') as cert:
                 cert.write(contents)
         self.new_crt_files = {}