The idea  is your computer running v2ray client sends traffic to an https website address like https://domainhostseotool.com/ray. This website returns normal website content except for location /ray. For this special location, the httpd server Apache behaviors as a reverse proxy…

After upgrading systemd from V219 to v247, journalctl stops working: journalctl -u v2ray Journal file /var/log/journal/xxxx/user-1000.journal uses an unsupported feature, ignoring file. Use SYSTEMD_LOG_LEVEL=debug journalctl –file=/var/log/journal/xxxx/user-1000.journal to see the details. SYSTEMD_LOG_LEVEL=debug journalctl –file=/var/log/journal/xxxx/user-1000.journal Journal effective settings seal=no keyed_hash=yes compress=no compress_threshold_bytes=8B…

First, you should know how to check systemd version on Linux. The system version command is:

You will see the output is “systemd 219″ on CentOS 7. This version is too low for many software that depend on systemd.…

You must know how to install a package with pip:

This will install the package components mainly to /usr/local/lib/python3.6/site-packages/xxx/, as well as some files to /usr/local/bin/, /usr/local/share/man/ and /usr/local/share/polkit-1/actions/. pip3 install command installs the latest version of package. If…

In proftpd.conf, there is a line

You can guess what DefaultRoot means. It means the default directory when an ftp client logs in. “DefaultRoot ~” means when a user connects and logs in ftp, it comes at his home…

I thought hard link is alias of a file and symbolic link is another file pointing to the linked file. So, I thought using symbolic link may be safer than using hard link. I thought “rm -f symlink” just delete…

When talking about apache proxy, we usually mean apache forward proxy. There is another kind of apache proxy: apache reverse proxy. The difference between apache forward proxy and apache reverse proxy is that apache forward server accepts connections from clients…

I never used “apachectl fullstatus” before. To get httpd status, I used “service httpd status” or “service httpd status -l” or “systemctl status httpd”. But now, I want to get more information about apache. You may hear about apache2ctl, but…

When you wget some url such as:

, you may get this error: ERROR: cannot verify curl.se’s certificate, issued by “/C=US/O=Let’s Encrypt/CN=R3”:Issued certificate has expired. This is because the server of this url uses Let’s Encrypt issued certificate, while…

Years ago, you may consider converting the charset of your mysql database from latin1 to utf8 as utf8 was prevailing and the default charset of mysql database is latin1. Today, you might want to change charset from utf8 to utf8mb4…