Linux Cache

Ubuntu示例文件备份脚本

12月 072021

#!/bin/bash
####################################
#
# Backup to NFS mount script.
#
####################################

# What to backup. 
backup_files="/home /var/spool/mail /etc /root /boot /opt"

# Where to backup to.
dest="/mnt/backup"

# Create archive filename.
day=$(date +%A)
hostname=$(hostname -s)
archive_file="$hostname-$day.tgz"

# Print start status message.
echo "Backing up $backup_files to $dest/$archive_file"
date
echo

# Backup the files using tar.
tar czf $dest/$archive_file $backup_files

# Print end status message.
echo
echo "Backup finished"
date

# Long listing of files in $dest to check file sizes.
ls -lh $dest

https://ubuntu.com/server/docs/backups-shell-scripts

DNS中TXT记录显示被引号截断的问题

域名 No Responses »

11月 112021

https://www.domaindiscount24.com/faq/en/txt-record

Please note

It needs time for changes in the DNS to take effect.

In case a single TXT record is longer than 255 characters you have to split it into two parts (like "1stpart" "2ndpart") to add it into a single line. This is because Strings in DNS records have a maximum of 255 characters according to RFC.
By splitting the record with double quotes this limitation can be avoided.

IPv6本地单播地址前缀计算示例

网络技术 No Responses »

9月 102021

获取时间戳

[root@s6 ~]# date +%s%N
1634089185225960225
[root@s6 ~]#

获取系统的唯一性ID

[root@s6 ~]# cat /etc/machine-id 
52e2104a451e6cc4c0cd3f75608ba59f
[root@s6 ~]#

通过hostnamectl查看

[root@s6 ~]# hostnamectl 
Static hostname: s6.linuxcache.com
Icon name: computer-vm
Chassis: vm
Machine ID: 52e2104a451e6cc4c0cd3f75608ba59f
Boot ID: 7b76dcb309d94c908ec297b10998cd38
Virtualization: kvm
Operating System: Fedora 34 (Server Edition)
CPE OS Name: cpe:/o:fedoraproject:fedora:34
Kernel: Linux 5.11.12-300.fc34.x86_64
Architecture: x86-64
Hardware Vendor: Vultr
Hardware Model: HFC
[root@s6 ~]#

拼接timestamp和machine-id并使用sha1算法计算校验值

printf <timestamp><machine-id> | sha1sum
printf 163408918522596022552e2104a451e6cc4c0cd3f75608ba59f | sha1sum

计算校验值

[root@s6 ~]# printf 163408918522596022552e2104a451e6cc4c0cd3f75608ba59f | sha1sum
e4819b79f35d65e8231cb7e23bf61fc76aab5571 -
[root@s6 ~]#

截取后5位16进制值

printf e4819b79f35d65e8231cb7e23bf61fc76aab5571 | cut -c 31-

截取成功

[root@s6 ~]# printf e4819b79f35d65e8231cb7e23bf61fc76aab5571 | cut -c 31-
c76aab5571
[root@s6 ~]#

拼接前缀

fd c7 6a ab 55 71
fdc7:6aab:5571::/64

使用ipcalc命令计算子网信息

[root@s6 ~]# ipcalc -6 fdc7:6aab:5571::/64
Full Network: fdc7:6aab:5571:0000:0000:0000:0000:0000/64
Network: fdc7:6aab:5571::/64
Netmask: ffff:ffff:ffff:ffff:: = 64

Address space: Unique Local Unicast
HostMin: fdc7:6aab:5571::
HostMax: fdc7:6aab:5571:0:ffff:ffff:ffff:ffff
Hosts/Net: 2^(64) = 18446744073709551616
[root@s6 ~]#

WireGuard 密钥对文件生成操作命令

信息安全 No Responses »

9月 092021

生成私钥

$ umask 077
$ wg genkey > privatekey

由私钥生成公钥

$ wg pubkey < privatekey > publickey

一次性生成私钥和公钥

$ wg genkey | tee privatekey | wg pubkey > publickey

WireGuard 客户端标准配置文件模板

信息安全 No Responses »

9月 062021

客户端标准配置文件

[Interface]
PrivateKey = 
Address = 172.16.0.1/24
DNS = 8.8.8.8, 8.8.4.4

[Peer]
PublicKey = 
AllowedIPs = 0.0.0.0/0, ::/0
Endpoint = hostname.com:51820
PersistentKeepalive = 25

生成二维码

方式1

$ qrencode -t ansiutf8 -r client.conf

方式2

$ qrencode -t ansiutf8 < client.conf

方式3

$ qrencode -t png -o client.png -r client.conf

AnyConnect predeploy/webdeploy区别

网络技术 No Responses »

8月 252021

AnyConnect Deployment Overview
Deploying AnyConnect refers to installing, configuring, and upgrading the AnyConnect client and its related files.

The Cisco AnyConnect Secure Mobility Client can be deployed to remote users by the following methods:

Predeploy—New installations and upgrades are done either by the end user, or by using an enterprise software management system (SMS).

Web Deploy—The AnyConnect package is loaded on the headend, which is either an ASA or FTD firewall, or an ISE server. When the user connects to a firewall or to ISE, AnyConnect is deployed to the client.

For new installations, the user connects to a headend to download the AnyConnect client. The client is either installed manually or automatically (web-launch).

Updates are done by AnyConnect running on a system where AnyConnect is already installed, or by directing the user to the ASA clientless portal.

When you deploy AnyConnect, you can include optional modules that enable extra features, and client profiles that configure the VPN and optional features.

Refer to the AnyConnect release notes for system, management, and endpoint requirements for ASA, IOS, Microsoft Windows, Linux, and macOS.

内容引用：

Cisco AnyConnect Secure Mobility Client Administrator Guide, Release 4.0 – Deploy AnyConnect [Cisco AnyConnect Secure Mobility Client] – Cisco

控制虚拟机中Linux文本终端屏幕分辨率

桌面应用 No Responses »

8月 052021

通过查看dmesg信息获取当前文本终端的默认显示分辨率

[ 4.426948] [drm] DMA map mode: Caching DMA mappings.
[ 4.427281] [drm] Capabilities:
[ 4.427282] [drm] Rect copy.
[ 4.427282] [drm] Cursor.
[ 4.427283] [drm] Cursor bypass.
[ 4.427283] [drm] Cursor bypass 2.
[ 4.427283] [drm] 8bit emulation.
[ 4.427284] [drm] Alpha cursor.
[ 4.427284] [drm] 3D.
[ 4.427284] [drm] Extended Fifo.
[ 4.427284] [drm] Multimon.
[ 4.427285] [drm] Pitchlock.
[ 4.427285] [drm] Irq mask.
[ 4.427285] [drm] Display Topology.
[ 4.427286] [drm] GMR.
[ 4.427286] [drm] Traces.
[ 4.427286] [drm] GMR2.
[ 4.427286] [drm] Screen Object 2.
[ 4.427287] [drm] Command Buffers.
[ 4.427287] [drm] Command Buffers 2.
[ 4.427287] [drm] Guest Backed Resources.
[ 4.427288] [drm] DX Features.
[ 4.427288] [drm] HP Command Queue.
[ 4.427288] [drm] Capabilities2:
[ 4.427289] [drm] Grow oTable.
[ 4.427289] [drm] IntraSurface copy.
[ 4.427289] [drm] DX3.
[ 4.427290] [drm] Max GMR ids is 64
[ 4.427291] [drm] Max number of GMR pages is 65536
[ 4.427292] [drm] Max dedicated hypervisor surface memory is 0 kiB
[ 4.427292] [drm] Maximum display memory size is 262144 kiB
[ 4.427293] [drm] VRAM at 0xe8000000 size is 131072 kiB
[ 4.427294] [drm] MMIO at 0xfe000000 size is 256 kiB
[ 4.437927] [TTM] Zone kernel: Available graphics memory: 996108 KiB
[ 4.464121] [drm] Screen Target Display device initialized
[ 4.464193] [drm] width 1280
[ 4.464211] [drm] height 768
[ 4.464229] [drm] bpp 32
[ 4.493584] [drm] Fifo max 0x00040000 min 0x00001000 cap 0x0000077f
[ 4.591064] [drm] Using command buffers with DMA pool.
[ 4.594738] [drm] Atomic: yes.
[ 4.594741] [drm] SM5 support available.

通过hwinfo命令查看当前可用的分辨率模式

[root@fedora ~]# hwinfo --framebuffer
02: None 00.0: 11001 VESA Framebuffer 
[Created at bios.459]
Unique ID: rdCR.O3PgoQaqFo1
Hardware Class: framebuffer
Model: "VMware virtual machine"
Vendor: "VMware, Inc"
Device: "VMware virtual machine"
SubVendor: "V M ware, Inc. VBE support 2.0"
SubDevice: 
Revision: "2.0"
Memory Size: 0 MB
Memory Range: 0xe8000000-??? (rw)
Mode 0x0300: 640x400 (+640), 8 bits
Mode 0x0301: 640x480 (+640), 8 bits
Mode 0x0303: 800x600 (+800), 8 bits
Mode 0x0305: 1024x768 (+1024), 8 bits
Mode 0x0307: 1280x1024 (+1280), 8 bits
Mode 0x030e: 320x200 (+640), 16 bits
Mode 0x0311: 640x480 (+1280), 16 bits
Mode 0x0314: 800x600 (+1600), 16 bits
Mode 0x0317: 1024x768 (+2048), 16 bits
Mode 0x031a: 1280x1024 (+2560), 16 bits
Mode 0x0320: 320x200 (+320), 8 bits
Mode 0x0321: 320x400 (+320), 8 bits
Mode 0x0322: 640x400 (+640), 8 bits
Mode 0x0323: 640x480 (+640), 8 bits
Mode 0x0324: 800x600 (+800), 8 bits
Mode 0x0325: 1024x768 (+1024), 8 bits
Mode 0x0326: 1152x864 (+1152), 8 bits
Mode 0x0327: 1280x960 (+1280), 8 bits
Mode 0x0328: 1280x1024 (+1280), 8 bits
Mode 0x0329: 1400x1050 (+1408), 8 bits
Mode 0x032a: 1600x1200 (+1600), 8 bits
Mode 0x032b: 1792x1344 (+1792), 8 bits
Mode 0x032c: 1856x1392 (+1856), 8 bits
Mode 0x032d: 1920x1440 (+1920), 8 bits
Mode 0x032e: 320x200 (+640), 16 bits
Mode 0x032f: 320x400 (+640), 16 bits
Mode 0x0330: 640x400 (+1280), 16 bits
Mode 0x0331: 640x480 (+1280), 16 bits
Mode 0x0332: 800x600 (+1600), 16 bits
Mode 0x0333: 1024x768 (+2048), 16 bits
Mode 0x0334: 1152x864 (+2304), 16 bits
Mode 0x0335: 1280x960 (+2560), 16 bits
Mode 0x0336: 1280x1024 (+2560), 16 bits
Mode 0x0337: 1400x1050 (+2816), 16 bits
Mode 0x0338: 1600x1200 (+3200), 16 bits
Mode 0x0339: 1792x1344 (+3584), 16 bits
Mode 0x033a: 1856x1392 (+3712), 16 bits
Mode 0x033b: 1920x1440 (+3840), 16 bits
Mode 0x033c: 320x200 (+1280), 24 bits
Mode 0x033d: 320x400 (+1280), 24 bits
Mode 0x033e: 640x400 (+2560), 24 bits
Mode 0x033f: 640x480 (+2560), 24 bits
Mode 0x0340: 800x600 (+3200), 24 bits
Mode 0x0341: 1024x768 (+4096), 24 bits
Mode 0x0342: 1152x864 (+4608), 24 bits
Mode 0x0343: 1280x960 (+5120), 24 bits
Mode 0x0344: 1280x1024 (+5120), 24 bits
Mode 0x0345: 1400x1050 (+5600), 24 bits
Mode 0x0346: 1600x1200 (+6400), 24 bits
Mode 0x0347: 1792x1344 (+7168), 24 bits
Mode 0x0348: 1856x1392 (+7424), 24 bits
Mode 0x0349: 1920x1440 (+7680), 24 bits
Mode 0x034a: 1366x768 (+1376), 8 bits
Mode 0x034b: 1366x768 (+2752), 16 bits
Mode 0x034c: 1366x768 (+5472), 24 bits
Mode 0x034d: 1680x1050 (+1696), 8 bits
Mode 0x034e: 1680x1050 (+3360), 16 bits
Mode 0x034f: 1680x1050 (+6720), 24 bits
Mode 0x0350: 1920x1200 (+1920), 8 bits
Mode 0x0351: 1920x1200 (+3840), 16 bits
Mode 0x0352: 1920x1200 (+7680), 24 bits
Mode 0x0353: 2048x1536 (+2048), 8 bits
Mode 0x0354: 2048x1536 (+4096), 16 bits
Mode 0x0355: 2048x1536 (+8192), 24 bits
Mode 0x0356: 320x240 (+320), 8 bits
Mode 0x0357: 320x240 (+640), 16 bits
Mode 0x0358: 320x240 (+1280), 24 bits
Mode 0x0359: 400x300 (+416), 8 bits
Mode 0x035a: 400x300 (+800), 16 bits
Mode 0x035b: 400x300 (+1600), 24 bits
Mode 0x035c: 512x384 (+512), 8 bits
Mode 0x035d: 512x384 (+1024), 16 bits
Mode 0x035e: 512x384 (+2048), 24 bits
Mode 0x035f: 854x480 (+864), 8 bits
Mode 0x0360: 854x480 (+1728), 16 bits
Mode 0x0361: 854x480 (+3424), 24 bits
Mode 0x0362: 1280x720 (+1280), 8 bits
Mode 0x0363: 1280x720 (+2560), 16 bits
Mode 0x0364: 1280x720 (+5120), 24 bits
Mode 0x0365: 1920x1080 (+1920), 8 bits
Mode 0x0366: 1920x1080 (+3840), 16 bits
Mode 0x0367: 1920x1080 (+7680), 24 bits
Mode 0x0368: 1280x800 (+1280), 8 bits
Mode 0x0369: 1280x800 (+2560), 16 bits
Mode 0x036a: 1280x800 (+5120), 24 bits
Mode 0x036b: 1440x900 (+1440), 8 bits
Mode 0x036c: 1440x900 (+2880), 16 bits
Mode 0x036d: 1440x900 (+5760), 24 bits
Mode 0x036e: 720x480 (+736), 8 bits
Mode 0x036f: 720x480 (+1440), 16 bits
Mode 0x0370: 720x480 (+2880), 24 bits
Mode 0x0371: 720x576 (+736), 8 bits
Mode 0x0372: 720x576 (+1440), 16 bits
Mode 0x0373: 720x576 (+2880), 24 bits
Mode 0x0374: 800x480 (+800), 8 bits
Mode 0x0375: 800x480 (+1600), 16 bits
Mode 0x0376: 800x480 (+3200), 24 bits
Mode 0x0377: 1280x768 (+1280), 8 bits
Mode 0x0378: 1280x768 (+2560), 16 bits
Mode 0x0379: 1280x768 (+5120), 24 bits
Config Status: cfg=new, avail=yes, need=no, active=unknown
[root@fedora ~]#

修改文本终端分辨率模式的三种方法

1）在Linux启动阶段输出可用分辨率模式并由用户选择

vga=ask

2）在Linux启动阶段手动添加分辨率模式参数

vga=0x0364

3）修改GRUB2引导菜单配置，永久新增分辨率模式参数

[root@fedora ~]# grubby --default-kernel
/boot/vmlinuz-5.11.12-300.fc34.x86_64
[root@fedora ~]# grubby --args="vga=0x0364" --update-kernel /boot/vmlinuz-5.11.12-300.fc34.x86_64
[root@fedora ~]#

修改GRUB2引导菜单配置并重启后查看GRUB2引导菜单的变化

查看分辨率为1280*720的虚拟机文本终端窗口

https://docs.fedoraproject.org/en-US/fedora/rawhide/system-administrators-guide/kernel-module-driver-configuration/Working_with_the_GRUB_2_Boot_Loader/#sec-Making_Persistent_Changes_to_a_GRUB_2_Menu_Using_the_grubby_Tool

YouTube视频分辨率和宽高比设置参考

流媒体 No Responses »

7月 302021

视频分辨率和宽高比

YouTube 会根据所用的平台和视频格式，以不同的宽高比播放视频。YouTube 视频播放器会自动根据每个视频的尺寸调整大小。

视频显示方式
YouTube 在计算机上的标准宽高比为 16:9。如果您的视频具有不同的宽高比，则播放器将自动变为理想尺寸以匹配您的视频和观看者的设备。

对于某些视频和设备宽高比（例如计算机浏览器中显示的 9:16 竖版视频），YouTube 可能会添加额外的内边框以实现理想的观看效果。内边框默认为白色，但在启用“深色主题背景”的情况下为深灰色。

为了实现理想效果，请避免直接在视频中添加内边框或黑边。视频自带的内边框会干扰 YouTube 根据您的视频尺寸和观看者的设备动态调整播放器的能力。

推荐的分辨率和宽高比

对于默认的 16:9 宽高比，请按以下分辨率进行编码：

2160p：3840x2160
1440p：2560x1440
1080p：1920x1080
720p：1280x720
480p：854x480
360p：640x360
240p：426x240

https://support.google.com/youtube/answer/6375112?hl=zh-Hans

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