Ben Chuanlong Du's Blog

It is never too late to learn.

Tips on Network

Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

Improve Network Speed

软路由让你的翻墙速度快十倍！LEDE软路由v2ray对比梅林固件(v2ray/LEDE/谷歌云)

https://zhuanlan.zhihu.com/p/129139369

https://www.zhihu.com/question/332524152

一个U盘优盘就翻墙 免费拥有VPN翻墙路由器的两种方法 Openwrt/LEDE软路由U盘优盘的制作 ButterflyVPN评测

QR Code for WiFi

WiFi Card print a QR code for connecting to your WiFi (wificard.io)

VPN/Proxy

https://www.youtube.com/watch?v=F6yh4b7ML5g

Reverse Proxy

nginx

caddy

https://engineering.hashnode.com/after-4-years-with-nginx-we-switched-to-caddy-here-is-why-cjxbv8eb2001ke8s1yl7ndroz

Expose Local Web Services to Public

Please refer to Expose Local Service to Public or detailed discussions.

General Tips

  1. Use the same wireless network name and password so that your laptop and phone recognize it automatically. This makes things much more convenient.

Debugging Network Issues

  1. Check whether you have block some services in /etc/hosts.allow or iptables, etc.

  2. http://192.168.0.1/ is the router address

  3. Turn off wireless router and moderm. Start wireless router and wait for 30 seconds, and then start the moderm.

Permanent Change to the File /etc/resolv.conf

Notice that the content of /etc/resolv.conf is dynamically managed. Content of the file might change after the host machine is rebooted. Below are some ways to make changes to the file /etc/resolv.conf permanent. (Notice that below are solutions for Linux machines only. Do NOT use any of the solutions below when you are building a Docker image as Docker has its own way of handling DNS.)

  1. Make /etc/resolv.conf immutable.

  2. Update the file /etc/dhcp/dhclient.conf

  3. use resolvconf

  4. more ...

https://kb.isc.org/docs/isc-dhcp-44-manual-pages-dhclientconf

https://www.techrepublic.com/article/how-to-set-dns-nameservers-in-ubuntu-server-18-04/

https://unix.stackexchange.com/questions/128220/how-do-i-set-my-dns-when-resolv-conf-is-being-overwritten

https://unix.stackexchange.com/questions/128220/how-do-i-set-my-dns-when-resolv-conf-is-being-overwritten/163506#163506

https://wiki.debian.org/resolv.conf

https://itsfoss.com/resolvconf-permanent-ubuntu/

https://askubuntu.com/questions/623940/network-manager-how-to-stop-nm-updating-etc-resolv-conf/623956#623956

https://askubuntu.com/questions/157154/how-do-i-include-lines-in-resolv-conf-that-wont-get-lost-on-reboot

https://www.linuxquestions.org/questions/linux-software-2/i-can%27t-change-file-permission-via-chattr-4175553888/

https://stackoverflow.com/questions/48578108/what-the-differences-between-chattr-i-file-and-chmod-w-file

https://askubuntu.com/questions/1006741/what-is-the-difference-between-chmod-and-chattr

List Network Cards

lspci | egrep -i --color 'network|ethernet'

Or you can use 

lshw -class network

IP Address

  1. To get the your public ip address, use the following simple command.

    curl ifconfig.me

    Or you can use https://www.ipify.org/ which provides A Simple Public IP Address API.

    curl https://api.ipify.org?format=json

  2. To scan for all ips in a local network, you can use the following command.

    arp-scan -l

    You can specify an device to scan by the option -I.

    arp-scan -l -I dev

    where "dev" is the device name of your net card. For example, if you use wireless network, "dev" is probably "wlan0".

Network Monitoring

  1. vnStat is a console-based tool for monitoring network traffic bandwidth usage. It uses the network interface statistics provided by the kernel as information source. This means that vnStat won't actually be sniffing any traffic and also ensures light use of system resources.

  2. Tcpdump is a network sniffer tool.

References

http://www.linuxandubuntu.com/home/best-network-monitoring-tools-for-linux

https://www.ittsystems.com/linux-network-monitor-tools-and-software/

https://techtalk.gfi.com/the-top-20-free-network-monitoring-and-analysis-tools-for-sys-admins/

https://www.tecmint.com/20-netstat-commands-for-linux-network-management/

https://www.tecmint.com/12-tcpdump-commands-a-network-sniffer-tool/

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