Posts Tagged ‘ CentOS

Visual Studio Code 的安裝說明,以及推薦的延伸模組 (Windows/Linux)

微軟開發的 Visual Studio Code (簡稱 VS Code) 是一套非常熱門的「編輯器」! VS Code 跨平台,且開放原始碼。它雖然僅是一個輕量版的編輯器,卻可經由安裝延伸模組來支援程式碼語法突顯、偵錯、自動補全、重構、Markdown...等琳瑯滿目功能,打造你夢想中的 IDE (整合開發環境)。

VS Code 預設僅支援 JavaScript、TypeScript、CSS、HTML,同樣能透過下載延伸模組來支援 Python、C/C++、Java、Perl、Go... 等其他程式語言。

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[Perl]如何在 Visual Studio Code 建立 Perl 的程式開發環境 (Windows/Linux)

據說 Perl 可能是近幾年會消失的 5 種程式語言之一,另外 4 個語言分別是 RubyHaskellObject-CR! 現在在 Visual Studio Code (簡稱 VS Code) 建立 Perl 的程式開發環境也算是幫 Perl 續一下命,大慈大悲、功德無量。

要建立好整個 Perl 的開發環境主要分為三個步驟:

  1. 安裝 Perl 的執行環境
  2. 安裝 VS Code Editor
  3. 在 VS Code 安裝 Perl 的延伸模組 (Extension)

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如何解決 TLS/SSL 使用了不安全的加密演算法: ARCFOUR、CBC、HMAC-MD5、HMAC-RIPEMD160

弱點掃瞄

弱點: TLS Service Supports Weak Cipher Suite

Transport Layer Security (TLS), the successor to Secure Socket Layer (SSL), is a network protocol that encrypt communications between TLS servers (e.g., websites) and TLS clients (e.g., web browsers). Every communication is secured by a cipher suite: a combination of several algorithms working in concert. Cryptographic algorithms do not have a defined lifetime, but academics, researchers, and nation states are constantly evaluating them for weaknesses. Consensus on which algorithms are untrustworthy evolves over time, and if a communication is protected with a weak cipher suite then that communication can be altered or decrypted.

  • Severity: Medium
  • Risk: A TLS service was observed supporting weak cipher suites.
  • Recommendation: Disable the cipher suites listed in the evidence column of the measurement.

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如何解決 SSH Server 使用了不安全的加密演算法: ARCFOUR、CBC、HMAC-MD5、HMAC-RIPEMD160

弱點掃瞄

弱點 1: SSH Supports Weak Cipher

The SSH server is configured to support either Arcfour or Cipher Block Chaining (CBC) mode cipher algorithms. SSH can be configured to use Counter (CTR) mode encryption instead of CBC. The use of Arcfour algorithms should be disabled.

  • Severity: Medium
  • Risk: A weak cipher has been detected.
  • Recommendation: Configure the SSH server to disable Arcfour and CBC ciphers.

弱點 2: SSH Supports Weak MAC

The SSH server is configured to support MD5 algorithm. The cryptographic strength depends upon the size of the key and algorithm that is used. A Modern MAC algorithms such as SHA1 or SHA2 should be used instead.

  • Severity: Medium
  • Risk: A weak Message Authentication Code (MAC) algorithm has been detected.
  • Recommendation: Configure the SSH server to disable the use of MD5.

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如何解決 Web/Mail Server 使用了不安全的 SSL 通訊協定

弱點掃瞄

弱點: SSL/TLS Service Supports Weak Protocol

Transport Layer Security (TLS), the successor to Secure Socket Layer (SSL), is a network protocol that encrypt communications between TLS servers (e.g., websites) and TLS clients (e.g., web browsers). Every communication is secured by a cipher suite: a combination of several algorithms working in concert. Networking protocols do not have a defined lifetime, but academics, researchers, and nation states are constantly evaluating them for weaknesses. Consensus on which protocols are untrustworthy evolves over time, and if communications are sent with a weak protocol then that communication can be altered or decrypted.

  • Severity: High
  • Risk: A TLS service was observed supporting weak protocols.
  • Recommendation: Disable the protocols listed in the evidence column of the measurement.

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如何自動將網站的 http:// 網址轉址為 https://

弱點掃瞄

弱點: Site does not enforce HTTPS

The site responds to HTTP requests without ultimately redirecting the browser to a secure version of the page. Since the site allows plaintext traffic, a man-in-the-middle attacker is able to read and modify any information passed between the site and the user. There are a variety of situations in which an attacker can intercept plaintext traffic in a man-in-the-middle position, including but not limited to:

  1. Open Wi-Fi Hotspots
  2. WPA/WPA2 encrypted hot-spots where the attacker connected before the victim
  3. Malicious Wi-Fi access points
  4. Compromised switches and routers
  5. ARP poisoning on the same wired network

It's important to remember that in many of the above situations, an attacker can not only read traffic, but also actively modify the traffic. Even if a site that does not contain sensitive information, an attacker can still inject malicious content to a user’s browser.

  • Severity: High
  • Risk: Site does not enforce the use of HTTPS encryption, leaving the user vulnerable to man-in-the-middle attackers (who can falsify data and inject malicious code).
  • Recommendation: Any site served to a user (possibly at the end of a redirect chain) should be served over HTTPS.

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CentOS 5/6 改為可用的 yum 套件庫來源 (2022)

若執行 yum 出現:

http://mirror.centos.org/centos/6/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"
Trying other mirror.
To address this issue please refer to the below knowledge base article

表示系統預設的 yum 套件庫可能已經不存在!

我們可以在 vault.centos.org 找到可用的套件庫來源:

  • vault.centos.org: http
  • archive.kernel.org: http - rsync (rsync://archive.kernel.org::centos-vault/)
  • linuxsoft.cern.ch: http - rsync (rsync://linuxsoft.cern.ch/centos-vault/)
  • mirror.nsc.liu: http - rsync (rsync://mirror.nsc.liu.se::centos-store/)

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Centos 6.x 如何停用 IPv6

為什麼要停用 IPv6?

  1. 不熟、抗拒學習
  2. IPv6 也要設 IP 反解 PTR
  3. Gmail 會擋沒有設 IPv6 反解的郵件

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CentOS 如何加入第三方 Yum 套件庫: EPEL

EPEL 的全稱為「Extra Packages for Enterprise Linux」,是由 Fedora 社群打造,為 RHEL 及衍生發行版如 CentOS、Scientific Linux、Rocky Linux、Oracle Linux...等提供高品質套件庫的專案。裝了 EPEL 之後,等於添加了一個資源豐富的第三方套件庫。

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CentOS 5/6 快速安裝 VPN Server (PPTP)

「VPN」是一種常用於中、大型企業或團體與團體間的私人網路的通訊方法。藉由 VPN 所建立的加密通道,可以讓你從外部存取公司內部的資源,或透過連線到 VPN 的 Server 當跳板,去存取被限制的外部資源 (俗稱「翻牆」)。

在使用 VPN 之前,你得先有一台提供服務的 VPN Server,現在滿多人會去租用國外的 VPS 當 Server,要架站兼翻牆,Linode 是不錯的選擇。

以下把握幾個重點即可快速完成 Linux 的 PPTP 的 VPN Server 架設:

  • PPP - 點對點協定 (Point-to-Point Protocol)
  • PPTP - 點對點通道協定 (Point-to-Point Tunneling Protocol)
  • iptables - 設定封包轉發規則

安裝步驟

1. 判斷 ppp 是否可用:

$ cat /dev/ppp
cat: /dev/ppp: No such device or address

如果出現跟上面一樣的訊息「No such device or address」,那不用擔心,這表示 ppp 是可用的,可以正常架設 pptp。

如果出現的是「Permission denied」,表示 ppp 是關閉的,下面的步驟就可以不用再看了。
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