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香港云服务器CentOS服务器安全配置策略
近期服务器频繁有被入侵的，大致分析了一下入侵行为，整理了需要做的安全策略：
管理机端设置：
1.跳板机权限只开放运维人?
a.运维人员密码必须重新设置,密码长度不小于8位
b.密码设置必须要有大小写，数字，特殊字符组合。
c.强制90天更改密码
d.设置密码避免重复使用
e.个人账户设定登录失败次数为6次，一旦超过6次，将会锁定账号。
2.跳板机禁止root登录，每周update
3.禁止在跳板机上保存登录密码，ip列表等信息，将history记录默认设置为500条。
4.修改PPTP vpn?务器账户密码，定期更新补丁。

服务端设置：
a.登录段配置同之前配置。
b.定期修改密码。
c.服务器端每周update补丁。
d.禁用root直接登录，创建运维人员单独账号。必要时使用sudo成为root进行管理
e.服务器禁止ping操作，增加安全性。
d.隐藏系统版本号，防止版本信息泄露
d.优化sysct.conf预防DDoS攻击
e.定时检查主要配置文件，系统主要目录是否有异常，可通过MD5校验如发现有变动重新分发一份。如/etc/passwd /etc/shadow /etc/group /etc/sysctl.conf, /bin /sbin等。

具体细节如下：
#设定用户90天修改密码，提前7天提醒

UserList=$(ls /home/|awk '{print $NF}'|grep -v lost+found)
for user in $UserList
do
chage -M 90 -W 7 $user
done


#禁ping

echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all


#设定用户过期时间90默认密码长度8位

cp /etc/login.defs /etc/login.defs.bak
sed -i '/PASS_MIN_LEN/s/[0-9]{1,6}/90/' /etc/login.defs
sed -i '/PASS_MIN_LEN/s/[0-9]{1,3}/8/' /etc/login.defs


#设定用户登录，普通用户登录识别超过6次锁定300s.

echo "account required pam_tally.so deny=100 no_magic_root reset" >>/etc/pam.d/system-auth
echo "auth required pam_tally.so onerr=fail deny=6 unlock_time=300" >>/etc/pam.d/system-auth


#隐藏系统版本号

mv /etc/issue /etc/isseu
mv /etc/issue.net /etc/isseu.net
mv /etc/redhat-release /etc/rehdat-release


#优化内核参数

echo '
# Kernel sysctl configuration file for Red Hat Linux
#
# For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and
# sysctl.conf(5) for more details.

# Controls IP packet forwarding
net.ipv4.ip_forward = 0

# Controls source route verification
net.ipv4.conf.default.rp_filter = 1

# Do not accept source routing
net.ipv4.conf.default.accept_source_route = 0

# Controls the System Request debugging functionality of the kernel
kernel.sysrq = 0

# Controls whether core dumps will append the PID to the core filename
# Useful for debugging multi-threaded applications
kernel.core_uses_pid = 1

# Controls the use of TCP syncookies
net.ipv4.tcp_syncookies = 1

# Controls the maximum size of a message, in bytes
kernel.msgmnb = 65536

# Controls the default maxmimum size of a mesage queue
kernel.msgmax = 65536

# Controls the maximum shared segment size, in bytes
kernel.shmmax = 68719476736

# Controls the maximum number of shared memory segments, in pages
kernel.shmall = 4294967296
# ------------- Kernel Optimization -------------
net.ipv4.tcp_max_tw_buckets = 60000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.netdev_max_backlog = 262144
net.core.somaxconn = 262144
net.ipv4.tcp_max_orphans = 3276800
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_synack_retries = 1
net.ipv4.tcp_syn_retries = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1
net.ipv4.tcp_keepalive_time = 30
net.ipv4.ip_local_port_range = 1024 65000
net.ipv4.ip_conntrack_max = 655360
net.ipv4.netfilter.ip_conntrack_max =655360
net.ipv4.netfilter.ip_conntrack_tcp_timeout_established = 180 ' >>/etc/sysctl.conf
#生效
sysctl -p


#记录histtory日志

echo '
#history
export HISTTIMEFORMAT="%F %T `whoami` "
USER_IP=`who -u am i 2>/dev/null| awk '{print $NF}'|sed -e 's/[()]//g'`
HISTDIR=/usr/local/bin/.history
if [ -z $USER_IP ]
then
USER_IP=`hostname`
fi
if [ ! -d $HISTDIR ]
then
mkdir -p $HISTDIR
chmod 777 $HISTDIR
fi
if [ ! -d $HISTDIR/${LOGNAME} ]
then
mkdir -p $HISTDIR/${LOGNAME}
chmod 300 $HISTDIR/${LOGNAME}
fi
export HISTSIZE=4000
DT=`date +%Y%m%d_%H%M%S`
export HISTFILE="$HISTDIR/${LOGNAME}/${USER_IP}.history.$DT"
chmod 600 $HISTDIR/${LOGNAME}/*.history* 2>/dev/null '>>/etc/profile


#安全登录

/etc/hosts.allow
#
# hosts.allow This file describes the names of the hosts which are
# allowed to use the local INET services, as decided
# by the '/usr/sbin/tcpd' server.
#


sshd:192.168.1.101

/etc/hosts.deny
#
# hosts.deny This file describes the names of the hosts which are
# *not* allowed to use the local INET services, as decided
# by the '/usr/sbin/tcpd' server.
#
# The portmap line is redundant, but it is left to remind you that
# the new secure portmap uses hosts.deny and hosts.allow. In particular
# you should know that NFS uses portmap!

sshd:all


#检查防火墙配置（开放指定用户地址登录|服务地址开放用户地址段）

iptables-save


#创建普通用户

useradd mdf
echo -e 'pwd123456'|passwd mdf --stdin


#禁止root登录权限

sed -i 's/#PermitRootLogin yes/PermitRootLogin no/g' /etc/ssh/sshd_config


#优化ssh链接慢问题

sed -i 's/GSSAPIAuthentication yes/GSSAPIAuthentication no/' /etc/ssh/sshd_config
sed -i '/#UseDNS yes/aUseDNS no' /etc/ssh/sshd_config
/etc/init.d/sshd restart

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