怎样在CentOS或RHEL系统上检查可用的安全更新

怎样在CentOS或RHEL系统上检查可用的安全更新，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。

当你更新系统时，根据你所在公司的安全策略，有时候可能只需要打上与安全相关的补丁。大多数情况下，这应该是出于程序兼容性方面的考量。那该怎样实践呢？有没有办法让 yum 只安装安全补丁呢？

答案是肯定的，可以用 yum 包管理器轻松实现。

在这篇文章中，我们不但会提供所需的信息。而且，我们会介绍一些额外的命令，可以帮你获取指定安全更新的详实信息。

希望这样可以启发你去了解并修复你列表上的那些漏洞。一旦有安全漏洞被公布，就必须更新受影响的软件，这样可以降低系统中的安全风险。

对于 RHEL 或 CentOS 6 系统，运行下面的 Yum 命令 来安装 yum 安全插件。

# yum -y install yum-plugin-security

在 RHEL 7&8 或是 CentOS 7&8 上面，这个插件已经是 yum 的一部分了，不用单独安装。

要列出全部可用的补丁（包括安全、Bug 修复以及产品改进），但不安装它们：

# yum updateinfo list availableLoaded plugins: changelog, package_upload, product-id, search-disabled-repos,              : subscription-manager, verify, versionlockRHSA-2014:1031 Important/Sec. 389-ds-base-1.3.1.6-26.el7_0.x86_64RHSA-2015:0416 Important/Sec. 389-ds-base-1.3.3.1-13.el7.x86_64RHBA-2015:0626 bugfix         389-ds-base-1.3.3.1-15.el7_1.x86_64RHSA-2015:0895 Important/Sec. 389-ds-base-1.3.3.1-16.el7_1.x86_64RHBA-2015:1554 bugfix         389-ds-base-1.3.3.1-20.el7_1.x86_64RHBA-2015:1960 bugfix         389-ds-base-1.3.3.1-23.el7_1.x86_64RHBA-2015:2351 bugfix         389-ds-base-1.3.4.0-19.el7.x86_64RHBA-2015:2572 bugfix         389-ds-base-1.3.4.0-21.el7_2.x86_64RHSA-2016:0204 Important/Sec. 389-ds-base-1.3.4.0-26.el7_2.x86_64RHBA-2016:0550 bugfix         389-ds-base-1.3.4.0-29.el7_2.x86_64RHBA-2016:1048 bugfix         389-ds-base-1.3.4.0-30.el7_2.x86_64RHBA-2016:1298 bugfix         389-ds-base-1.3.4.0-32.el7_2.x86_64

要统计补丁的大约数量，运行下面的命令：

# yum updateinfo list available | wc -l11269

想列出全部可用的安全补丁但不安装，以下命令用来展示你系统里已安装和待安装的推荐补丁：

# yum updateinfo list security allLoaded plugins: changelog, package_upload, product-id, search-disabled-repos,              : subscription-manager, verify, versionlock  RHSA-2014:1031 Important/Sec. 389-ds-base-1.3.1.6-26.el7_0.x86_64  RHSA-2015:0416 Important/Sec. 389-ds-base-1.3.3.1-13.el7.x86_64  RHSA-2015:0895 Important/Sec. 389-ds-base-1.3.3.1-16.el7_1.x86_64  RHSA-2016:0204 Important/Sec. 389-ds-base-1.3.4.0-26.el7_2.x86_64  RHSA-2016:2594 Moderate/Sec.  389-ds-base-1.3.5.10-11.el7.x86_64  RHSA-2017:0920 Important/Sec. 389-ds-base-1.3.5.10-20.el7_3.x86_64  RHSA-2017:2569 Moderate/Sec.  389-ds-base-1.3.6.1-19.el7_4.x86_64  RHSA-2018:0163 Important/Sec. 389-ds-base-1.3.6.1-26.el7_4.x86_64  RHSA-2018:0414 Important/Sec. 389-ds-base-1.3.6.1-28.el7_4.x86_64  RHSA-2018:1380 Important/Sec. 389-ds-base-1.3.7.5-21.el7_5.x86_64  RHSA-2018:2757 Moderate/Sec.  389-ds-base-1.3.7.5-28.el7_5.x86_64  RHSA-2018:3127 Moderate/Sec.  389-ds-base-1.3.8.4-15.el7.x86_64  RHSA-2014:1031 Important/Sec. 389-ds-base-libs-1.3.1.6-26.el7_0.x86_64

要显示所有待安装的安全补丁：

# yum updateinfo list security all | grep -v "i"   RHSA-2014:1031 Important/Sec. 389-ds-base-1.3.1.6-26.el7_0.x86_64  RHSA-2015:0416 Important/Sec. 389-ds-base-1.3.3.1-13.el7.x86_64  RHSA-2015:0895 Important/Sec. 389-ds-base-1.3.3.1-16.el7_1.x86_64  RHSA-2016:0204 Important/Sec. 389-ds-base-1.3.4.0-26.el7_2.x86_64  RHSA-2016:2594 Moderate/Sec.  389-ds-base-1.3.5.10-11.el7.x86_64  RHSA-2017:0920 Important/Sec. 389-ds-base-1.3.5.10-20.el7_3.x86_64  RHSA-2017:2569 Moderate/Sec.  389-ds-base-1.3.6.1-19.el7_4.x86_64  RHSA-2018:0163 Important/Sec. 389-ds-base-1.3.6.1-26.el7_4.x86_64  RHSA-2018:0414 Important/Sec. 389-ds-base-1.3.6.1-28.el7_4.x86_64  RHSA-2018:1380 Important/Sec. 389-ds-base-1.3.7.5-21.el7_5.x86_64  RHSA-2018:2757 Moderate/Sec.  389-ds-base-1.3.7.5-28.el7_5.x86_64

要统计全部安全补丁的大致数量，运行下面的命令：

# yum updateinfo list security all | wc -l3522

下面根据已装软件列出可更新的安全补丁。这包括 bugzilla（bug 修复）、CVE（知名漏洞数据库）、安全更新等：

# yum updateinfo list security 或者 # yum updateinfo list sec Loaded plugins: changelog, package_upload, product-id, search-disabled-repos,              : subscription-manager, verify, versionlock RHSA-2018:3665 Important/Sec. NetworkManager-1:1.12.0-8.el7_6.x86_64RHSA-2018:3665 Important/Sec. NetworkManager-adsl-1:1.12.0-8.el7_6.x86_64RHSA-2018:3665 Important/Sec. NetworkManager-bluetooth-1:1.12.0-8.el7_6.x86_64RHSA-2018:3665 Important/Sec. NetworkManager-config-server-1:1.12.0-8.el7_6.noarchRHSA-2018:3665 Important/Sec. NetworkManager-glib-1:1.12.0-8.el7_6.x86_64RHSA-2018:3665 Important/Sec. NetworkManager-libnm-1:1.12.0-8.el7_6.x86_64RHSA-2018:3665 Important/Sec. NetworkManager-ppp-1:1.12.0-8.el7_6.x86_64RHSA-2018:3665 Important/Sec. NetworkManager-team-1:1.12.0-8.el7_6.x86_64RHSA-2018:3665 Important/Sec. NetworkManager-tui-1:1.12.0-8.el7_6.x86_64RHSA-2018:3665 Important/Sec. NetworkManager-wifi-1:1.12.0-8.el7_6.x86_64RHSA-2018:3665 Important/Sec. NetworkManager-wwan-1:1.12.0-8.el7_6.x86_64

显示所有与安全相关的更新，并且返回一个结果来告诉你是否有可用的补丁：

# yum --security check-updateLoaded plugins: changelog, package_upload, product-id, search-disabled-repos, subscription-manager, verify, versionlockrhel-7-server-rpms                                                                                                                            | 2.0 kB  00:00:00--> policycoreutils-devel-2.2.5-20.el7.x86_64 from rhel-7-server-rpms excluded (updateinfo)--> smc-raghumalayalam-fonts-6.0-7.el7.noarch from rhel-7-server-rpms excluded (updateinfo)--> amanda-server-3.3.3-17.el7.x86_64 from rhel-7-server-rpms excluded (updateinfo)--> 389-ds-base-libs-1.3.4.0-26.el7_2.x86_64 from rhel-7-server-rpms excluded (updateinfo)--> 1:cups-devel-1.6.3-26.el7.i686 from rhel-7-server-rpms excluded (updateinfo)--> openwsman-client-2.6.3-3.git4391e5c.el7.i686 from rhel-7-server-rpms excluded (updateinfo)--> 1:emacs-24.3-18.el7.x86_64 from rhel-7-server-rpms excluded (updateinfo)--> augeas-libs-1.4.0-2.el7_4.2.i686 from rhel-7-server-rpms excluded (updateinfo)--> samba-winbind-modules-4.2.3-10.el7.i686 from rhel-7-server-rpms excluded (updateinfo)--> tftp-5.2-11.el7.x86_64 from rhel-7-server-rpms excluded (updateinfo)..35 package(s) needed for security, out of 115 availableNetworkManager.x86_64                        1:1.12.0-10.el7_6            rhel-7-server-rpmsNetworkManager-adsl.x86_64                   1:1.12.0-10.el7_6            rhel-7-server-rpmsNetworkManager-bluetooth.x86_64              1:1.12.0-10.el7_6            rhel-7-server-rpmsNetworkManager-config-server.noarch          1:1.12.0-10.el7_6            rhel-7-server-rpmsNetworkManager-glib.x86_64                   1:1.12.0-10.el7_6            rhel-7-server-rpmsNetworkManager-libnm.x86_64                  1:1.12.0-10.el7_6            rhel-7-server-rpmsNetworkManager-ppp.x86_64                    1:1.12.0-10.el7_6            rhel-7-server-rpms

列出所有可用的安全补丁，并且显示其详细信息：

# yum info-sec..===============================================================================  tzdata bug fix and enhancement update===============================================================================  Update ID : RHBA-2019:0689    Release : 0       Type : bugfix     Status : final     Issued : 2019-03-28 19:27:44 UTCDescription : The tzdata packages contain data files with rules for various            : time zones.            :            : The tzdata packages have been updated to version            : 2019a, which addresses recent time zone changes.            : Notably:            :            : * The Asia/Hebron and Asia/Gaza zones will start            :   DST on 2019-03-30, rather than 2019-03-23 as            :   previously predicted.            : * Metlakatla rejoined Alaska time on 2019-01-20,            :   ending its observances of Pacific standard time.            :            : (BZ#1692616, BZ#1692615, BZ#1692816)            :            : Users of tzdata are advised to upgrade to these            : updated packages.   Severity : None

如果你想要知道某个更新的具体内容，可以运行下面这个命令：

# yum updateinfo RHSA-2019:0163 Loaded plugins: changelog, package_upload, product-id, search-disabled-repos, subscription-manager, verify, versionlockrhel-7-server-rpms                                                                                                                            | 2.0 kB  00:00:00===============================================================================  Important: kernel security, bug fix, and enhancement update===============================================================================  Update ID : RHSA-2019:0163    Release : 0       Type : security     Status : final     Issued : 2019-01-29 15:21:23 UTC    Updated : 2019-01-29 15:23:47 UTC       Bugs : 1641548 - CVE-2018-18397 kernel: userfaultfd bypasses tmpfs file permissions            : 1641878 - CVE-2018-18559 kernel: Use-after-free due to race condition in AF_PACKET implementation       CVEs : CVE-2018-18397            : CVE-2018-18559Description : The kernel packages contain the Linux kernel, the core of any            : Linux operating system.            :            : Security Fix(es):            :            : * kernel: Use-after-free due to race condition in            :   AF_PACKET implementation (CVE-2018-18559)            :            : * kernel: userfaultfd bypasses tmpfs file            :   permissions (CVE-2018-18397)            :            : For more details about the security issue(s),            : including the impact, a CVSS score, and other            : related information, refer to the CVE page(s)            : listed in the References section.            :            : Bug Fix(es):            :            : These updated kernel packages include also            : numerous bug fixes and enhancements. Space            : precludes documenting all of the bug fixes in this            : advisory. See the descriptions in the related            : Knowledge Article:            : https://access.redhat.com/articles/3827321   Severity : Importantupdateinfo info done

跟之前类似，你可以只查询那些通过 CVE 释出的系统漏洞：

# yum updateinfo list cves Loaded plugins: changelog, package_upload, product-id, search-disabled-repos,              : subscription-manager, verify, versionlockCVE-2018-15688 Important/Sec. NetworkManager-1:1.12.0-8.el7_6.x86_64CVE-2018-15688 Important/Sec. NetworkManager-adsl-1:1.12.0-8.el7_6.x86_64CVE-2018-15688 Important/Sec. NetworkManager-bluetooth-1:1.12.0-8.el7_6.x86_64CVE-2018-15688 Important/Sec. NetworkManager-config-server-1:1.12.0-8.el7_6.noarchCVE-2018-15688 Important/Sec. NetworkManager-glib-1:1.12.0-8.el7_6.x86_64CVE-2018-15688 Important/Sec. NetworkManager-libnm-1:1.12.0-8.el7_6.x86_64CVE-2018-15688 Important/Sec. NetworkManager-ppp-1:1.12.0-8.el7_6.x86_64CVE-2018-15688 Important/Sec. NetworkManager-team-1:1.12.0-8.el7_6.x86_64

你也可以查看那些跟 bug 修复相关的更新，运行下面的命令：

# yum updateinfo list bugfix | less Loaded plugins: changelog, package_upload, product-id, search-disabled-repos,              : subscription-manager, verify, versionlockRHBA-2018:3349 bugfix NetworkManager-1:1.12.0-7.el7_6.x86_64RHBA-2019:0519 bugfix NetworkManager-1:1.12.0-10.el7_6.x86_64RHBA-2018:3349 bugfix NetworkManager-adsl-1:1.12.0-7.el7_6.x86_64RHBA-2019:0519 bugfix NetworkManager-adsl-1:1.12.0-10.el7_6.x86_64RHBA-2018:3349 bugfix NetworkManager-bluetooth-1:1.12.0-7.el7_6.x86_64RHBA-2019:0519 bugfix NetworkManager-bluetooth-1:1.12.0-10.el7_6.x86_64RHBA-2018:3349 bugfix NetworkManager-config-server-1:1.12.0-7.el7_6.noarchRHBA-2019:0519 bugfix NetworkManager-config-server-1:1.12.0-10.el7_6.noarch

要想得到待安装更新的摘要信息，运行这个：

# yum updateinfo summaryLoaded plugins: changelog, package_upload, product-id, search-disabled-repos, subscription-manager, verify, versionlockrhel-7-server-rpms                                                                                                                            | 2.0 kB  00:00:00Updates Information Summary: updates    13 Security notice(s)         9 Important Security notice(s)         3 Moderate Security notice(s)         1 Low Security notice(s)    35 Bugfix notice(s)     1 Enhancement notice(s)updateinfo summary done

如果只想打印出低级别的安全更新，运行下面这个命令。类似的，你也可以只查询重要级别和中等级别的安全更新。

# yum updateinfo list sec | grep -i "Low" RHSA-2019:0201 Low/Sec.       libgudev1-219-62.el7_6.3.x86_64RHSA-2019:0201 Low/Sec.       systemd-219-62.el7_6.3.x86_64RHSA-2019:0201 Low/Sec.       systemd-libs-219-62.el7_6.3.x86_64RHSA-2019:0201 Low/Sec.       systemd-sysv-219-62.el7_6.3.x86_64

看完上述内容，你们掌握怎样在CentOS或RHEL系统上检查可用的安全更新的方法了吗？如果还想学到更多技能或想了解更多相关内容，欢迎关注行业资讯频道，感谢各位的阅读！