Example analysis to fix problems in historical Linux images

Fix for issues with historical Linux images

The ECS cloud server created by the historical Linux image may have NTP and YUM not configured, and may also have security vulnerabilities that have been exposed recently. Please follow the steps below to repair them, which will make your cloud server more secure. You can also use the YUM service provided by Alibaba Cloud to install software, and use the free NTP provided by Alibaba Cloud for time synchronization.

1. Configure NTP

Regardless of the distribution, back up /etc/ntp.conf first, then replace its content with the following:

# ntp.conf

#

# ntpd config for aliyun ecs.

#

# 6LAN+6LAN+3WAN

# [email protected]

# 2014.8.11

#

driftfile /var/lib/ntp/drift

pidfile /var/run/ntpd.pid

logfile /var/log/ntp.log

# Access Control Support

restrict default ignore

restrict -6 default ignore

restrict 127.0.0.1

restrict 192.168.0.0 mask 255.255.0.0 nomodify notrap nopeer noquery

restrict 172.16.0.0 mask 255.240.0.0 nomodify notrap nopeer noquery

restrict 100.64.0.0 mask 255.192.0.0 nomodify notrap nopeer noquery

restrict 10.0.0.0 mask 255.0.0.0 nomodify notrap nopeer noquery

restrict ntp1.aliyun.com nomodify notrap nopeer noquery

restrict ntp2.aliyun.com nomodify notrap nopeer noquery

restrict ntp3.aliyun.com nomodify notrap nopeer noquery

restrict ntp4.aliyun.com nomodify notrap nopeer noquery

restrict ntp5.aliyun.com nomodify notrap nopeer noquery

restrict ntp6.aliyun.com nomodify notrap nopeer noquery

# local clock

server 127.127.1.0

fudge 127.127.1.0 stratum 10

#public ntp server

server ntp1.aliyun.com iburst minpoll 4 maxpoll 10

server ntp2.aliyun.com iburst minpoll 4 maxpoll 10

server ntp3.aliyun.com iburst minpoll 4 maxpoll 10

server ntp4.aliyun.com iburst minpoll 4 maxpoll 10

server ntp5.aliyun.com iburst minpoll 4 maxpoll 10

server ntp6.aliyun.com iburst minpoll 4 maxpoll 10

#Private ntp server

server ntp1.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp2.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp3.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp4.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp5.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp6.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

#New private ntp server

server ntp7.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp8.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp9.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp10.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp11.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

server ntp12.cloud.aliyuncs.com iburst minpoll 4 maxpoll 10

2. Update software sources

0. First confirm the image's current Linux system distribution and version number.

If there is a lsb_release command, execute:

lsb_release -a

Otherwise execute

cat /etc/issue

1. For CentOS, back up the CentOS-Base.repo and epel.repo files in /etc/yum.repos.d/ and execute the following corresponding commands according to the CentOS version:

CentOS 5:

wget -qO /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo

wget -qO /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-5.repo

CentOS 6:

wget -qO /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo

wget -qO /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo

CentOS 7:

wget -qO /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

wget -qO /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo

After the repo file is downloaded, execute:

yum makecache

2. For Aliyun 5.7, back up /etc/yum.repos.d/CentOS-Base.repo, then execute:

wget -qO /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/aliyun-5.repo

After the repo file is downloaded, execute:

yum makecache

3. For Ubuntu, back up the /etc/apt/sources.list file and execute the command according to the distribution version:

Ubuntu 12.04:

wget -qO /etc/apt/sources.list http://mirrors.aliyun.com/repo/ubuntu1204-lts.list

Ubuntu 14.04:

wget -qO /etc/apt/sources.list http://mirrors.aliyun.com/repo/ubuntu1404-lts.list

Then execute:

apt-get update

4. For Debian, back up the /etc/apt/sources.list file and execute the command according to the distribution version:

debian6:

wget -qO /etc/apt/sources.list http://mirrors.aliyun.com/repo/debian6-lts.list

debian7:

wget -qO /etc/apt/sources.list http://mirrors.aliyun.com/repo/debian7-lts.list

Then execute:

apt-get update

3. Security vulnerability patch

It mainly repairs currently known major security vulnerabilities. The software that needs to be upgraded includes: bash, glibc, openssl, wget, and ntp.

Before executing the following commands, you need to ensure that the system's current software source has been set correctly.

1. For CentOS and Aliyun Linux, execute:

yum update bash glibc openssl wget ntp

2. For Ubuntu and Debian, execute:

apt-get install bash libc6 libc-bin openssl wget ntp

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