Vixual

弱点扫瞄

弱点: 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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弱点扫瞄

弱点 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.

弱点 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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弱点扫瞄

弱点: 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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弱点扫瞄

弱点: 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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这些指令的执行档通常是放在 C:\Windows\System32\，可在这些地方执行指令:

• 开始功能表的“执行”
• Win + R 的执行视窗
• Win + Q 或 Win + S 的搜寻视窗
• cmd 命令提示字符
• 档案总管的“网址列”

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我的电脑在某次更新 Windows 10 之后，原本已设定好不让它自动关机的电脑竟会进入休眠状态! 原因似乎是进入休眠的时间被改动了，而在 Windows 的设定中却不容易找到“休眠”的细部选项!

这 Windows 可真爱找麻烦!

先来看一下 Windows 10 关机选单的 4 个选项做为相关知识:

1. 睡眠 (Sleep, S3): 会将桌面及应用程式的状态写入至内存，让电脑以极低的耗电方式维持在开机的状态，以便在唤醒电脑时，可以立即回到睡眠前的电脑状态。从 Windows Vista 起，睡眠 (Sleep) 模式已取代了待命 (Standby) 模式。
2. 休眠 (Hibernate, S4): 会将桌面及应用程式的状态写入至磁盘再关闭电脑的电源，电脑下次开机会恢复到休眠前的电脑状态。从休眠状态下开机的速度会比睡眠还慢。
3. 关机 (Shut down, S5): 关闭所有应用程式并关闭电脑的电源，不会自动储存任何状态。
4. 重新开机 (Restart): 关闭所有应用程式并重新启动电脑及作业系统。

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若执行 yum 出现:

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

表示系统默认的 yum 套件库可能已经不存在!

我们可以在 vault.centos.org 找到可用的套件库来源:

• 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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安装流程

1. xrdp 是放在 EPEL 套件库，所以我们要先安装 EPEL。依据不同版本的 CentOS 请参考: CentOS 如何加入第三方 Yum 套件库: EPEL。
2. 安装 xrdp 及 tigervnc server:

yum install xrdp tigervnc-server

3. 启动 xrdp

service xrdp start

4. 加到开机自动执行

chkconfig xrdp on

PS. 只要启动 xrdp 即可，tigervnc server 装好后就不用理它了。

设定与登入

设定与登入的方式与之前的教学一样，请自行参考。

参考网页

1. 安装 xrdp v0.6.0 (原始档)
2. Linux 上的远端桌面中继程式: xrdp (v0.4.2)
3. CentOS 如何加入第三方 Yum 套件库: EPEL

我的某个 Linode VPS 不明所以被 GFW 给封锁了!!无助的我，在不更换 VPS 的前题下，可以尝试变更 IP 或是迁移机房。

早期 Linode 要做这两件事都必须提交 Ticket，透过客服人员来处理，但现在的客服人员似乎已经不再帮忙变更 IP 了!!

不过没关系，只要学会使用 Linode 的“Clone”功能，我们也可以自己来变更 IP 或迁移机房。

Linode 的费用

要执行“Clone”的功能之前，我们要先来了解一下 Linode 的相关费用:

1. 早期 Linode 帐号的付款方式是采用: 包月 + 预付，一次买一年有 10% 折扣、买两年有 15% 折扣。如果没有用满一个月就删除 VPS 的话，那剩下的时间仍会归还等比例的金额至你的帐户。如果将方案降级也会归还差额。(2019/04/01 起，已强制转为计时 + 月结)
2. 2014 年之后新用户的付款方式是采用: 计时 + 月结。
3. 最小的计费单位是“小时”，超过一秒钟都算你一个小时。
4. 只要一“新增”VPS 就会开始计费，即便你的 VPS 没有开机。
5. 启用“Backups”功能会增加约 20~25% 费用。
6. 在执行“Clone”的过程中会有两个 VPS 同时在计费。
7. 可以将计费方从由“包月”改为“计时”，但没有将“计时”改为“包月”的功能。

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为什么要停用 IPv6?

1. 不熟、抗拒学习
2. IPv6 也要设 IP 反解 PTR
3. Gmail 会挡没有设 IPv6 反解的邮件

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