如何在 CentOS 或 RHEL 系統上檢查可用的安全更新?

Magesh Maruthamuthu發表於2019-06-05

當你更新系統時,根據你所在公司的安全策略,有時候可能只需要打上與安全相關的補丁。大多數情況下,這應該是出於程式相容性方面的考量。那該怎樣實踐呢?有沒有辦法讓 yum 只安裝安全補丁呢?

答案是肯定的,可以用 yum 包管理器輕鬆實現。

在這篇文章中,我們不但會提供所需的資訊。而且,我們會介紹一些額外的命令,可以幫你獲取指定安全更新的詳實資訊。

希望這樣可以啟發你去了解並修復你列表上的那些漏洞。一旦有安全漏洞被公佈,就必須更新受影響的軟體,這樣可以降低系統中的安全風險。

對於 RHEL 或 CentOS 6 系統,執行下面的 Yum 命令 來安裝 yum 安全外掛。

# yum -y install yum-plugin-security

在 RHEL 7&8 或是 CentOS 7&8 上面,這個外掛已經是 yum 的一部分了,不用單獨安裝。

要列出全部可用的補丁(包括安全、Bug 修復以及產品改進),但不安裝它們:

# yum updateinfo list available
Loaded 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
RHBA-2015:0626 bugfix         389-ds-base-1.3.3.1-15.el7_1.x86_64
RHSA-2015:0895 Important/Sec. 389-ds-base-1.3.3.1-16.el7_1.x86_64
RHBA-2015:1554 bugfix         389-ds-base-1.3.3.1-20.el7_1.x86_64
RHBA-2015:1960 bugfix         389-ds-base-1.3.3.1-23.el7_1.x86_64
RHBA-2015:2351 bugfix         389-ds-base-1.3.4.0-19.el7.x86_64
RHBA-2015:2572 bugfix         389-ds-base-1.3.4.0-21.el7_2.x86_64
RHSA-2016:0204 Important/Sec. 389-ds-base-1.3.4.0-26.el7_2.x86_64
RHBA-2016:0550 bugfix         389-ds-base-1.3.4.0-29.el7_2.x86_64
RHBA-2016:1048 bugfix         389-ds-base-1.3.4.0-30.el7_2.x86_64
RHBA-2016:1298 bugfix         389-ds-base-1.3.4.0-32.el7_2.x86_64

要統計補丁的大約數量,執行下面的命令:

# yum updateinfo list available | wc -l
11269

想列出全部可用的安全補丁但不安裝,以下命令用來展示你係統裡已安裝和待安裝的推薦補丁:

# yum updateinfo list security all
Loaded 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

要顯示所有待安裝的安全補丁:

# 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

要統計全部安全補丁的大致數量,執行下面的命令:

# yum updateinfo list security all | wc -l
3522

下面根據已裝軟體列出可更新的安全補丁。這包括 bugzilla(bug 修復)、CVE(知名漏洞資料庫)、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_64
RHSA-2018:3665 Important/Sec. NetworkManager-adsl-1:1.12.0-8.el7_6.x86_64
RHSA-2018:3665 Important/Sec. NetworkManager-bluetooth-1:1.12.0-8.el7_6.x86_64
RHSA-2018:3665 Important/Sec. NetworkManager-config-server-1:1.12.0-8.el7_6.noarch
RHSA-2018:3665 Important/Sec. NetworkManager-glib-1:1.12.0-8.el7_6.x86_64
RHSA-2018:3665 Important/Sec. NetworkManager-libnm-1:1.12.0-8.el7_6.x86_64
RHSA-2018:3665 Important/Sec. NetworkManager-ppp-1:1.12.0-8.el7_6.x86_64
RHSA-2018:3665 Important/Sec. NetworkManager-team-1:1.12.0-8.el7_6.x86_64
RHSA-2018:3665 Important/Sec. NetworkManager-tui-1:1.12.0-8.el7_6.x86_64
RHSA-2018:3665 Important/Sec. NetworkManager-wifi-1:1.12.0-8.el7_6.x86_64
RHSA-2018:3665 Important/Sec. NetworkManager-wwan-1:1.12.0-8.el7_6.x86_64

顯示所有與安全相關的更新,並且返回一個結果來告訴你是否有可用的補丁:

# yum --security check-update
Loaded plugins: changelog, package_upload, product-id, search-disabled-repos, subscription-manager, verify, versionlock
rhel-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 available
NetworkManager.x86_64                        1:1.12.0-10.el7_6            rhel-7-server-rpms
NetworkManager-adsl.x86_64                   1:1.12.0-10.el7_6            rhel-7-server-rpms
NetworkManager-bluetooth.x86_64              1:1.12.0-10.el7_6            rhel-7-server-rpms
NetworkManager-config-server.noarch          1:1.12.0-10.el7_6            rhel-7-server-rpms
NetworkManager-glib.x86_64                   1:1.12.0-10.el7_6            rhel-7-server-rpms
NetworkManager-libnm.x86_64                  1:1.12.0-10.el7_6            rhel-7-server-rpms
NetworkManager-ppp.x86_64                    1:1.12.0-10.el7_6            rhel-7-server-rpms

列出所有可用的安全補丁,並且顯示其詳細資訊:

# 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 UTC
Description : 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

如果你想要知道某個更新的具體內容,可以執行下面這個命令:

# yum updateinfo RHSA-2019:0163

Loaded plugins: changelog, package_upload, product-id, search-disabled-repos, subscription-manager, verify, versionlock
rhel-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-2018-18559
Description : 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 : Important
updateinfo info done

跟之前類似,你可以只查詢那些通過 CVE 釋出的系統漏洞:

# yum updateinfo list cves

Loaded plugins: changelog, package_upload, product-id, search-disabled-repos,
              : subscription-manager, verify, versionlock
CVE-2018-15688 Important/Sec. NetworkManager-1:1.12.0-8.el7_6.x86_64
CVE-2018-15688 Important/Sec. NetworkManager-adsl-1:1.12.0-8.el7_6.x86_64
CVE-2018-15688 Important/Sec. NetworkManager-bluetooth-1:1.12.0-8.el7_6.x86_64
CVE-2018-15688 Important/Sec. NetworkManager-config-server-1:1.12.0-8.el7_6.noarch
CVE-2018-15688 Important/Sec. NetworkManager-glib-1:1.12.0-8.el7_6.x86_64
CVE-2018-15688 Important/Sec. NetworkManager-libnm-1:1.12.0-8.el7_6.x86_64
CVE-2018-15688 Important/Sec. NetworkManager-ppp-1:1.12.0-8.el7_6.x86_64
CVE-2018-15688 Important/Sec. NetworkManager-team-1:1.12.0-8.el7_6.x86_64

你也可以檢視那些跟 bug 修復相關的更新,執行下面的命令:

# yum updateinfo list bugfix | less

Loaded plugins: changelog, package_upload, product-id, search-disabled-repos,
              : subscription-manager, verify, versionlock
RHBA-2018:3349 bugfix NetworkManager-1:1.12.0-7.el7_6.x86_64
RHBA-2019:0519 bugfix NetworkManager-1:1.12.0-10.el7_6.x86_64
RHBA-2018:3349 bugfix NetworkManager-adsl-1:1.12.0-7.el7_6.x86_64
RHBA-2019:0519 bugfix NetworkManager-adsl-1:1.12.0-10.el7_6.x86_64
RHBA-2018:3349 bugfix NetworkManager-bluetooth-1:1.12.0-7.el7_6.x86_64
RHBA-2019:0519 bugfix NetworkManager-bluetooth-1:1.12.0-10.el7_6.x86_64
RHBA-2018:3349 bugfix NetworkManager-config-server-1:1.12.0-7.el7_6.noarch
RHBA-2019:0519 bugfix NetworkManager-config-server-1:1.12.0-10.el7_6.noarch

要想得到待安裝更新的摘要資訊,執行這個:

# yum updateinfo summary
Loaded plugins: changelog, package_upload, product-id, search-disabled-repos, subscription-manager, verify, versionlock
rhel-7-server-rpms                                                                                                                            | 2.0 kB  00:00:00
Updates 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

如果只想列印出低階別的安全更新,執行下面這個命令。類似的,你也可以只查詢重要級別和中等級別的安全更新。

# yum updateinfo list sec | grep -i "Low"

RHSA-2019:0201 Low/Sec.       libgudev1-219-62.el7_6.3.x86_64
RHSA-2019:0201 Low/Sec.       systemd-219-62.el7_6.3.x86_64
RHSA-2019:0201 Low/Sec.       systemd-libs-219-62.el7_6.3.x86_64
RHSA-2019:0201 Low/Sec.       systemd-sysv-219-62.el7_6.3.x86_64

via: https://www.2daygeek.com/check-list-view-find-available-security-updates-on-redhat-rhel-centos-system/

作者:Magesh Maruthamuthu 選題:lujun9972 譯者:jdh8383 校對:wxy

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