disable_ipv6.sh

#!/bin/bash
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Copyright Clairvoyant 2016

PATH=/usr/bin:/usr/sbin:/bin:/sbin:/usr/local/bin

DATE=$(date +'%Y%m%d%H%M%S')

# Function to discover basic OS details.
discover_os() {
  if command -v lsb_release >/dev/null; then
    # CentOS, Ubuntu, RedHatEnterpriseServer, Debian, SUSE LINUX
    # shellcheck disable=SC2034
    OS=$(lsb_release -is)
    # CentOS= 6.10, 7.2.1511, Ubuntu= 14.04, RHEL= 6.10, 7.5, SLES= 11
    # shellcheck disable=SC2034
    OSVER=$(lsb_release -rs)
    # 7, 14
    # shellcheck disable=SC2034
    OSREL=$(echo "$OSVER" | awk -F. '{print $1}')
    # Ubuntu= trusty, wheezy, CentOS= Final, RHEL= Santiago, Maipo, SLES= n/a
    # shellcheck disable=SC2034
    OSNAME=$(lsb_release -cs)
  else
    if [ -f /etc/redhat-release ]; then
      if [ -f /etc/almalinux-release ]; then
        # shellcheck disable=SC2034
        OS=AlmaLinux
        # 8.6
        # shellcheck disable=SC2034
        OSVER=$(rpm -qf /etc/almalinux-release --qf='%{VERSION}\n')
        # shellcheck disable=SC2034
        OSREL=$(echo "$OSVER" | awk -F. '{print $1}')
      elif [ -f /etc/centos-release ]; then
        # shellcheck disable=SC2034
        OS=CentOS
        # 7.5.1804.4.el7.centos, 6.10.el6.centos.12.3
        # shellcheck disable=SC2034
        OSVER=$(rpm -qf /etc/centos-release --qf='%{VERSION}.%{RELEASE}\n' | awk -F. '{print $1"."$2}')
        # shellcheck disable=SC2034
        OSREL=$(rpm -qf /etc/centos-release --qf='%{VERSION}\n')
      else
        # shellcheck disable=SC2034
        OS=RedHatEnterpriseServer
        # 7.5, 6Server
        # shellcheck disable=SC2034
        OSVER=$(rpm -qf /etc/redhat-release --qf='%{VERSION}\n')
        if [ "$OSVER" == "6Server" ]; then
          # shellcheck disable=SC2034
          OSVER=$(rpm -qf /etc/redhat-release --qf='%{RELEASE}\n' | awk -F. '{print $1"."$2}')
          # shellcheck disable=SC2034
          OSNAME=Santiago
        else
          # shellcheck disable=SC2034
          OSNAME=Maipo
        fi
        # shellcheck disable=SC2034
        OSREL=$(echo "$OSVER" | awk -F. '{print $1}')
      fi
    elif [ -f /etc/SuSE-release ]; then
      if grep -q "^SUSE Linux Enterprise Server" /etc/SuSE-release; then
        # shellcheck disable=SC2034
        OS="SUSE LINUX"
      fi
      # shellcheck disable=SC2034
      OSVER=$(rpm -qf /etc/SuSE-release --qf='%{VERSION}\n' | awk -F. '{print $1}')
      # shellcheck disable=SC2034
      OSREL=$(rpm -qf /etc/SuSE-release --qf='%{VERSION}\n' | awk -F. '{print $1}')
      # shellcheck disable=SC2034
      OSNAME="n/a"
    fi
  fi
}

echo "********************************************************************************"
echo "*** $(basename "$0")"
echo "********************************************************************************"
# Check to see if we are on a supported OS.
discover_os
if [ "$OS" != RedHatEnterpriseServer ] && [ "$OS" != CentOS ] && [ "$OS" != AlmaLinux ] && [ "$OS" != Debian ] && [ "$OS" != Ubuntu ]; then
  echo "ERROR: Unsupported OS."
  exit 3
fi

echo "** Before disabling IPv6:"
ip -6 address

if [ "$OS" == RedHatEnterpriseServer ] || [ "$OS" == CentOS ] || [ "$OS" == AlmaLinux ]; then
  echo "** sysctl method"
  echo "** Disabling IPv6 kernel configuration..."
  # https://access.redhat.com/solutions/8709
  # https://wiki.centos.org/FAQ/CentOS7#head-8984faf811faccca74c7bcdd74de7467f2fcd8ee
  # https://wiki.centos.org/FAQ/CentOS6#head-d47139912868bcb9d754441ecb6a8a10d41781df
  if [ -d /etc/sysctl.d ]; then
    if grep -q net.ipv6.conf.all.disable_ipv6 /etc/sysctl.conf; then
      sed -i -e '/^net.ipv6.conf.all.disable_ipv6/d' /etc/sysctl.conf
    fi
    if grep -q net.ipv6.conf.default.disable_ipv6 /etc/sysctl.conf; then
      sed -i -e '/^net.ipv6.conf.default.disable_ipv6/d' /etc/sysctl.conf
    fi
    echo "# Tuning for Hadoop installation." >/etc/sysctl.d/cloudera-ipv6.conf
    # shellcheck disable=SC2129
    echo "# CLAIRVOYANT" >>/etc/sysctl.d/cloudera-ipv6.conf
    echo "net.ipv6.conf.all.disable_ipv6 = 1" >>/etc/sysctl.d/cloudera-ipv6.conf
    echo "net.ipv6.conf.default.disable_ipv6 = 1" >>/etc/sysctl.d/cloudera-ipv6.conf
    chown root:root /etc/sysctl.d/cloudera-ipv6.conf
    chmod 0644 /etc/sysctl.d/cloudera-ipv6.conf
    sysctl -p /etc/sysctl.d/cloudera-ipv6.conf
    if [ "$OSREL" == 7 ]; then
      echo "*** Running dracut..."
      dracut -f
    elif [ "$OSREL" == 6 ]; then
      cp -p /etc/hosts /etc/hosts."${DATE}"
      sed -i -e 's/^[[:space:]]*::/#::/' /etc/hosts
    fi
  else
    if grep -q net.ipv6.conf.all.disable_ipv6 /etc/sysctl.conf; then
      sed -i -e "/^net.ipv6.conf.all.disable_ipv6/s|=.*|= 1|" /etc/sysctl.conf
    else
      echo "net.ipv6.conf.all.disable_ipv6 = 1" >>/etc/sysctl.conf
    fi
    if grep -q net.ipv6.conf.default.disable_ipv6 /etc/sysctl.conf; then
      sed -i -e "/^net.ipv6.conf.default.disable_ipv6/s|=.*|= 1|" /etc/sysctl.conf
    else
      echo "net.ipv6.conf.default.disable_ipv6 = 1" >>/etc/sysctl.conf
    fi
    sysctl -p /etc/sysctl.conf
  fi

#  if [ "$OSREL" == 7 ]; then
#    echo "** kernel module method"
#    echo "** Disabling IPv6 kernel module..."
#    cp -p /etc/default/grub /etc/default/grub."${DATE}"
#    # Alternatively use "ipv6.disable_ipv6=1".
#    if grep -q ipv6.disable /etc/default/grub; then
#      sed -i -e '/^GRUB_CMDLINE_LINUX=/s|ipv6.disable=.|ipv6.disable=1|' /etc/default/grub
#    else
#      sed -i -e '/^GRUB_CMDLINE_LINUX=/s|"$| ipv6.disable=1"|' /etc/default/grub
#    fi
#    if [ -f /boot/efi/EFI/redhat/grub.cfg ]; then
#      grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg
#    else
#      grub2-mkconfig -o /boot/grub2/grub.cfg
#    fi
#  elif [ "$OSREL" == 6 ]; then
#    echo "** kernel module method"
#    echo "** Disabling IPv6 kernel module..."
#    cat <<EOF >/etc/modprobe.d/cloudera-ipv6.conf
## CLAIRVOYANT
## Tuning for Hadoop installation.
#options ipv6 disable=1
#EOF
#    chown root:root /etc/modprobe.d/cloudera-ipv6.conf
#    chmod 0644 /etc/modprobe.d/cloudera-ipv6.conf
#    echo "** Unloading IPv6 kernel module..."
#    rmmod ipv6 &>/dev/null
#  fi

  echo "** Stopping IPv6 firewall..."
  service ip6tables stop
  chkconfig ip6tables off

elif [ "$OS" == Debian ] || [ "$OS" == Ubuntu ]; then
  echo "** sysctl method"
  echo "** Disabling IPv6 kernel configuration..."
  # https://wiki.debian.org/DebianIPv6#How_to_turn_off_IPv6
  # https://wiki.ubuntu.com/IPv6#Disabling_IPv6
  # https://askubuntu.com/questions/440649/how-to-disable-ipv6-in-ubuntu-14-04
  if grep -q net.ipv6.conf.all.disable_ipv6 /etc/sysctl.conf; then
    sed -i -e '/^net.ipv6.conf.all.disable_ipv6/d' /etc/sysctl.conf
  fi
  if grep -q net.ipv6.conf.default.disable_ipv6 /etc/sysctl.conf; then
    sed -i -e '/^net.ipv6.conf.default.disable_ipv6/d' /etc/sysctl.conf
  fi
  #if grep -q net.ipv6.conf.lo.disable_ipv6 /etc/sysctl.conf; then
  #  sed -i -e '/^net.ipv6.conf.lo.disable_ipv6/d' /etc/sysctl.conf
  #fi
  echo "# Tuning for Hadoop installation." >/etc/sysctl.d/cloudera-ipv6.conf
  # shellcheck disable=SC2129
  echo "# CLAIRVOYANT" >>/etc/sysctl.d/cloudera-ipv6.conf
  echo "net.ipv6.conf.all.disable_ipv6 = 1" >>/etc/sysctl.d/cloudera-ipv6.conf
  echo "net.ipv6.conf.default.disable_ipv6 = 1" >>/etc/sysctl.d/cloudera-ipv6.conf
  #echo "net.ipv6.conf.lo.disable_ipv6 = 1" >>/etc/sysctl.d/cloudera-ipv6.conf
  chown root:root /etc/sysctl.d/cloudera-ipv6.conf
  chmod 0644 /etc/sysctl.d/cloudera-ipv6.conf
  service procps restart
fi
# https://www.suse.com/support/kb/doc.php?id=7015035
# https://www.suse.com/support/kb/doc/?id=7012111

echo "** After disabling IPv6:"
ip -6 address

exit 0

# Fix any breakage in other applications.
if [ "$OS" == RedHatEnterpriseServer ] || [ "$OS" == CentOS ] || [ "$OS" == AlmaLinux ]; then
  if rpm -q postfix >/dev/null; then
    echo "** Disabling IPv6 in Postfix..."
    cp -p /etc/postfix/main.cf /etc/postfix/main.cf."${DATE}"
#mja needs work : assumes 127.0.0.1
    postconf inet_interfaces
    postconf -e inet_interfaces=127.0.0.1
    service postfix condrestart
  fi
elif [ "$OS" == Debian ] || [ "$OS" == Ubuntu ]; then
  :
fi

echo "** Disabling IPv6 in /etc/ssh/sshd_config..."
cp -p /etc/ssh/sshd_config /etc/ssh/sshd_config."${DATE}"
sed -e '/# CLAIRVOYANT$/d' \
    -e '/^AddressFamily /d' \
    -e '/^ListenAddress /d' \
    -i /etc/ssh/sshd_config
#mja needs work : assumes 0.0.0.0
cat <<EOF >>/etc/ssh/sshd_config
# Hadoop: Disable IPv6 support # CLAIRVOYANT
AddressFamily inet             # CLAIRVOYANT
ListenAddress 0.0.0.0          # CLAIRVOYANT
# Hadoop: Disable IPv6 support # CLAIRVOYANT
EOF
service ssh restart

if [ -f /etc/netconfig ]; then
  echo "** Disabling IPv6 in netconfig..."
  cp -p /etc/netconfig /etc/netconfig."${DATE}"
  sed -e '/inet6/d' -i /etc/netconfig
fi