centos7.2系统优化 原

1 修改网卡名称为eth0

#mv ifcfg-eno16777729 ifcfg-eth0

#vi /etc/sysconfig/grub

GRUB_TIMEOUT=5

GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"

GRUB_DEFAULT=saved

GRUB_DISABLE_SUBMENU=true

GRUB_TERMINAL_OUTPUT="console"

GRUB_CMDLINE_LINUX="net.ifnames=0 biosdevname=0 rhgb quiet net.ifnames=0 biosdevname=0"

GRUB_DISABLE_RECOVERY="true"

修改 /etc/udev/rules.d/90-eno-fix.rules名称

#grub2-mkconfig -o /boot/grub2/grub.cfg #生成启动菜单

Generating grub configuration file ...

Found linux image: /boot/vmlinuz-3.10.0-327.el7.x86_64

Found initrd image: /boot/initramfs-3.10.0-327.el7.x86_64.img

Found linux image: /boot/vmlinuz-0-rescue-e8675ae79abd41309dac42388f8d9116

Found initrd image: /boot/initramfs-0-rescue-e8675ae79abd41309dac42388f8d9116.img

#reboot

#ip addr 或者

#yum install net-tools #默认centos7不支持ifconfig 需要看装net-tools包

2.更新系统

3.修改文件属性,最低权限原则

chmod 700 /bin/rpm 只有root权限用户才可以使用rpm命定,安装软件包

chmod 664 /etc/hosts

chmod 644 /etc/passwd

chmod 644 /etc/exports

chmod 644 /etc/issue

chmod 664 /var/log/wtmp

chmod 664 /var/log/btmp

chmod 644 /etc/services

chmod 600 /etc/shadow

chmod 600 /etc/login.defs

chmod 600 /etc/hosts.allow

chmod 600 /etc/hosts.deny

chmod 600 /etc/securetty

chmod 600 /etc/security

chmod 600 /etc/ssh/ssh_host_key

chmod 600 /etc/ssh/sshd_config

chmod 600 /var/log/lastlog

chmod 600 /var/log/messages

4. 添加用户fang

[root@bogon ~]# useradd fang

[root@bogon ~]# echo 123456 | passwd --stdin fang

Changing password for user fang.

passwd: all authentication tokens updated successfully.

[root@bogon ~]# usermod -G wheel fang

[root@bogon ~]# sed -i '6s/^#//g' /etc/pam.d/su

[root@bogon ~]# grep wheel /etc/pam.d/su #只有WHEEL组的可以su

# Uncomment the following line to implicitly trust users in the "wheel" group.

#auth sufficient pam_wheel.so trust use_uid

# Uncomment the following line to require a user to be in the "wheel" group.

auth required pam_wheel.so use_uid

扩展:为用户fang添加sudo，除关机外的其他所有操作：

# visudo

Cmnd_Alias SHUTDOWN = /sbin/halt, /sbin/shutdown, /sbin/poweroff, /sbin/reboot, /sbin/init

fang ALL=(ALL) ALL,!SHUTDOWN

%wheel ALL=(ALL) ALL,!SHUTDOWN #修改wheel组的权限，禁止关机

Defaults logfile=/var/log/sudo.log

5 禁用selinux

[root@bogon ~]# grep -i ^selinux /etc/selinux/config

SELINUX=enforcing

SELINUXTYPE=targeted

[root@bogon ~]# sed -i '/^SELINUX/s/enforcing/disabled/g' /etc/selinux/config

[root@bogon ~]# getenforce

Enforcing

6.关闭防火墙安装iptables

systemctl stop firewalld.service 

systemctl disable firewalld.service

yum install iptables-services -y #安装

7.修改主机名

[root@bogon ~]# hostnamectl set-hostname hequan.com

[root@bogon ~]# hostname

hequan.com

8.查看并管理服务

[root@hequan ~]# systemctl -t service

[root@hequan ~]# systemctl list-unit-files -t service

yum install -y bash-completion #补全服务名称，退出bash再进就可以

9.设置字符集

[root@hequan ~]# echo $LANG

zh_CN.UTF-8

[root@hequan ~]# vi /etc/locale.conf

LANG="en_US.UTF-8"

[root@hequan ~]# source /etc/locale.conf

10.yum

yum install -y cmake vim wget lrzsz htop

安装163源

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

cd /etc/yum.repos.d/

wget http://mirrors.163.com/.help/CentOS7-Base-163.repo

yum clean all

yum makecache

其他

yum -y install yum-plugin-priorities ##安装优先级插件

sed -i -e "s/\]$/\]\npriority=1/g" /etc/yum.repos.d/CentOS-Base.repo ##设置基本yum源的优先级为1

yum -y install epel-release ##安装epel源

sed -i -e "s/\]$/\]\npriority=5/g" /etc/yum.repos.d/epel.repo ##设置优先级为5

sed -i -e "s/enabled=1/enabled=0/g" /etc/yum.repos.d/epel.repo ##禁用epel源

yum -y install http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el7.rf.x86_64.rpm ##安装rpmforge的源

sed -i -e "s/\]$/\]\npriority=10/g" /etc/yum.repos.d/rpmforge.repo ##设置优先级为10

sed -i -e "s/enabled = 1/enabled = 0/g" /etc/yum.repos.d/rpmforge.repo ##禁用yum源

使用方法：yum --enablerepo=rpmforge install [Package]

安装epel源

yum -y install epel-release

11 配置sshd

ListenAddress 0.0.0.0 ##只启用ipv4

/etc/ssh/sshd_config

PermitRootLogin no ##禁止root使用ssh登录

MaxAuthTries 2 ##两次不行就切断重新SSH启动登入

PubkeyAuthentication no ##禁止证书登陆AuthorizedKeysFile /dev/null

ChallengeResponseAuthentication yes禁止SSH客户端记住密码

加快ssh登录速度

GSSAPIAuthentication no ##关闭 GSSAPIUseDNS no ##禁止DNS 反向解析

一般 SSH 依次进行的认证方法的是 publickey, gssapi-keyex, gssapi-with-mic, password， 这个你可以ssh -v开启 debug 模式在连接日志看到。   一般用户只使用 password 认证方式，但前面 3 个认证过程系统还是会尝试，这就浪费时间了，也就造成 SSH 登录慢

AllowTcpForwarding no禁止使用SSH映射Socks5访问外国网站等等

12 加大打开文件数的限制（open files）

ulimit -n

ulimit -a

vi /etc/security/limits.conf

最后添加

* soft nofile 1024000

* hard nofile 1024000

hive - nofile 1024000

hive - nproc 1024000

用户进程限制

# sed -i 's#4096#65535#g' /etc/security/limits.d/20-nproc.conf #加大普通用户限制 也可以改为unlimited

# egrep -v "^$|^#" /etc/security/limits.d/20-nproc.conf 

* soft nproc 65535

root soft nproc unlimited

reboot

13 优化内核

cat /etc/sysctl.conf

#CTCDN系统优化参数

#关闭ipv6节省系统资源

net.ipv6.conf.all.disable_ipv6 = 1

net.ipv6.conf.default.disable_ipv6 = 1

#决定检查过期多久邻居条目

net.ipv4.neigh.default.gc_stale_time=120

#使用arp_announce / arp_ignore解决ARP映射问题

net.ipv4.conf.default.arp_announce = 2

net.ipv4.conf.all.arp_announce=2

net.ipv4.conf.lo.arp_announce=2

# 避免放大攻击

net.ipv4.icmp_echo_ignore_broadcasts = 1

# 开启恶意icmp错误消息保护

net.ipv4.icmp_ignore_bogus_error_responses = 1

#关闭路由转发

net.ipv4.ip_forward = 0

net.ipv4.conf.all.send_redirects = 0

net.ipv4.conf.default.send_redirects = 0

#开启反向路径过滤

net.ipv4.conf.all.rp_filter = 1

net.ipv4.conf.default.rp_filter = 1

#处理无源路由的包

net.ipv4.conf.all.accept_source_route = 0

net.ipv4.conf.default.accept_source_route = 0

#关闭sysrq功能

kernel.sysrq = 0

#core文件名中添加pid作为扩展名

kernel.core_uses_pid = 1

# 开启SYN洪水攻击保护

net.ipv4.tcp_syncookies = 1

#修改消息队列长度

kernel.msgmnb = 65536

kernel.msgmax = 65536

#设置最大内存共享段大小bytes

kernel.shmmax = 68719476736

kernel.shmall = 4294967296

#timewait的数量，默认180000

net.ipv4.tcp_max_tw_buckets = 6000

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

#每个网络接口接收数据包的速率比内核处理这些包的速率快时，允许送到队列的数据包的最大数目

net.core.netdev_max_backlog = 262144

#限制仅仅是为了防止简单的DoS 攻击

net.ipv4.tcp_max_orphans = 3276800

#未收到客户端确认信息的连接请求的最大值

net.ipv4.tcp_max_syn_backlog = 262144

net.ipv4.tcp_timestamps = 0

#内核放弃建立连接之前发送SYNACK 包的数量

net.ipv4.tcp_synack_retries = 1

#内核放弃建立连接之前发送SYN 包的数量

net.ipv4.tcp_syn_retries = 1

#启用timewait 快速回收

net.ipv4.tcp_tw_recycle = 1

#开启重用。允许将TIME-WAIT sockets 重新用于新的TCP 连接

net.ipv4.tcp_tw_reuse = 1

net.ipv4.tcp_mem = 94500000 915000000 927000000

net.ipv4.tcp_fin_timeout = 1

#当keepalive 起用的时候，TCP 发送keepalive 消息的频度。缺省是2 小时

net.ipv4.tcp_keepalive_time = 1800

net.ipv4.tcp_keepalive_probes = 3

net.ipv4.tcp_keepalive_intvl = 15

#允许系统打开的端口范围

net.ipv4.ip_local_port_range = 1024 65000

#修改防火墙表大小，默认65536

net.netfilter.nf_conntrack_max=655350

net.netfilter.nf_conntrack_tcp_timeout_established=1200

# 确保无人能修改路由表

net.ipv4.conf.all.accept_redirects = 0

net.ipv4.conf.default.accept_redirects = 0

net.ipv4.conf.all.secure_redirects = 0

net.ipv4.conf.default.secure_redirects = 0

sysctl -p #生效

14 时间设置

yum install chrony

vi /etc/chrony.conf

server 0.centos.pool.ntp.org

server 3.europe.pool.ntp.org

systemctl enable chronyd.service

systemctl start chronyd.service

timedatectl set-timezone Asia/Shanghai

timedatectl set-time "2015-01-21 11:50:00"（可以只修改其中一个）修改日期时间

timedatectl 查看时间状态

chronyc sources -v 查看时间同步源

chronyc sourcestats -v

hwclock -w #先同步一遍时间到硬件时间

15、远程5分钟无操作自动注销:

vim /etc/profile

最后添加:

export TMOUT=300   ---5分钟自动注销下来

找到

HISTSIZE=1000

修改为:

HISTSIZE=100 --减少日记字节为100KB,太大内容过多容易漏重要信息.

HISTTIMEFORMAT=”%Y-%m-%d %H:%M:%S”

16.禁止IP伪装

vim /etc/host.conf

在里面加上：

nospoof on

17临时文件安全

临时文件不应该有执行权限

/tmp

/dev/sda3 /tmp ext4 nosuid，noexec，nodev，rw 0 0

同时使用符号连接将/var/tmp 指向 /tmp

/dev/shm

none /dev/shm tmpfs defaults，nosuid，noexec，rw 0 0

18 PAM 插件认证加固配置

配置文件

ls /etc/pam.d/chfn crond login passwd remote runuser-l smtp ssh-keycat sudo-i system-auth-acchsh fingerprint-auth newrole password-auth run_init smartcard-auth smtp.postfix su su-lconfig-util fingerprint-auth-ac other password-auth-ac runuser smartcard-auth-ac sshd sudo system-auth

认证插件

ls /lib64/security/

18.1. pam_tally2.so

此模块的功能是，登陆错误输入密码3次，5分钟后自动解禁，在未解禁期间输入正确密码也无法登陆。

在配置文件 /etc/pam.d/sshd 顶端加入

auth required pam_tally2.so deny=3 onerr=fail unlock_time=300

查看失败次数

# pam_tally2Login Failures Latest failure Fromroot 14 07/12/13 15:44:37 192.168.6.2neo 8 07/12/13 15:45:36 192.168.6.2

重置计数器

# pam_tally2 -r -u rootLogin Failures Latest failure Fromroot 14 07/12/13 15:44:37 192.168.6.2# pam_tally2 -r -u neoLogin Failures Latest failure Fromneo 8 07/12/13 15:45:36 192.168.6.2

pam_tally2 计数器日志保存在 /var/log/tallylog 注意，这是二进制格式的文件

例 1. /etc/pam.d/sshd - pam_tally2.so

# cat /etc/pam.d/sshd

#%PAM-1.0auth required pam_tally2.so deny=3 onerr=fail unlock_time=300auth required pam_sepermit.soauth include password-authaccount required pam_nologin.soaccount include password-authpassword include password-auth# pam_selinux.so close should be the first session rulesession required pam_selinux.so closesession required pam_loginuid.so# pam_selinux.so open should only be followed by sessions to be executed in the user contextsession required pam_selinux.so open env_paramssession optional pam_keyinit.so force revokesession include password-auth

以上配置root用户不受限制, 如果需要限制root用户，参考下面

auth required pam_tally2.so deny=3 unlock_time=5 even_deny_root root_unlock_time=1800

18.2. pam_listfile.so

用户登陆限制

将下面一行添加到 /etc/pam.d/sshd 中，这里采用白名单方式，你也可以采用黑名单方式

auth required pam_listfile.so item=user sense=allow file=/etc/ssh/whitelist onerr=fail

将允许登陆的用户添加到 /etc/ssh/whitelist，除此之外的用户将不能通过ssh登陆到你的系统

# cat /etc/ssh/whitelistneowww

例 2. /etc/pam.d/sshd - pam_listfile.so

# cat /etc/pam.d/sshd#%PAM-1.0auth required pam_listfile.so item=user sense=allow file=/etc/ssh/whitelist onerr=failauth required pam_tally2.so deny=3 onerr=fail unlock_time=300auth required pam_sepermit.soauth include password-authaccount required pam_nologin.soaccount include password-authpassword include password-auth# pam_selinux.so close should be the first session rulesession required pam_selinux.so closesession required pam_loginuid.so# pam_selinux.so open should only be followed by sessions to be executed in the user contextsession required pam_selinux.so open env_paramssession optional pam_keyinit.so force revokesession include password-auth

sense=allow 白名单方式, sense=deny 黑名单方式

auth required pam_listfile.so item=user sense=deny file=/etc/ssh/blacklist onerr=fail

更多细节请查看手册 $ man pam_listfile

18.3. pam_access.so

编辑 /etc/pam.d/sshd 文件，加入下面一行

account required pam_access.so

保存后重启sshd进程

编辑 /etc/security/access.conf 文件cat >> /etc/security/access.conf << EOF- : root : ALL EXCEPT 192.168.6.1EOF

只能通过 192.168.6.1 登陆, 添加多个IP地址

- : root : ALL EXCEPT 192.168.6.1 192.168.6.2

测试是否生效

18.4. pam_wheel.so

限制普通用户通过su命令提升权限至root. 只有属于wheel组的用户允许通过su切换到root用户

编辑 /etc/pam.d/su 文件，去掉下面的注释

auth required pam_wheel.so use_uid

修改用户组别，添加到wheel组

# usermod -G wheel www# id wwwuid=501(www) gid=501(www) groups=501(www),10(wheel)

没有加入到wheel组的用户使用su时会提示密码不正确。

$ su - rootPassword:su: incorrect password

18.5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

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