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  WireGuard VPN Troubleshooting

When you are working as a network/cluster admin for you team to config the WireGuard VPN for other members, you may meet some of the problems below and these are the solution you can try to fix them. ----------------------------------------------------------------------------------------------------------- Problem [1]: The WireGuard handshake request send from the client can be received from the server but the server's response was blocked at some where so the client can not receive serv...

   WIREGUARD,VPN,TROUBLESHOOTING     2021-12-14 09:17:46

  What we still can’t do client-side

With the rise of all these APIs and the browser race to implement them, you’d think that currently we can do pretty much everything in JavaScript and even if we currently can’t due to browser support issues, we will once the specs are implemented. Unfortunately, that’s not true. There are still things we can’t do, and there’s no specification to address them at the time of this writing and no way to do them with the APIs we already have (or if there is a ...

   Chanllenge,Client side,Server side     2012-01-10 07:22:31

  gethostbyname vs getaddrinfo

getaddrinfo is slower than ping when resolving domain names. I think ping uses gethostbyname to resolve a domain name. The question becomes whether getaddrinfo is slower than gethostbyname. After testing with both functions, we find that getaddrinfo is really slow compared to gethostbyname. By strace tracking,  we find getaddrinfo will communicate with DNS server 10 times and gethostbyname will communicate with DNS server communication twice.gethostbyname is an old way to resolve domain nam...

   C++,network,DNS     2012-08-15 14:06:34

  New HTTP status code: 451 Unavailable for Legal Reasons

On June 11th,2012, Google proposed a new HTTP status code to indicate webpage contents which are not conform to law. The new HTTP status code is 451 Unavailable for Legal Reasons. Google Android Developer Advocate Tim Bray submitted the draft for the new HTTP status code, it will be used on some webpages which can not be served because of legal reasons. Visitors will know that the page cannot be seen because of the government censorship.According to the draft, responses using this status code sh...

   HTTP status,451,Tim Bray     2012-06-12 09:07:44

  Handy PHP functions should be in your toolkit

When developing projects, there are always some common work should be accomplished, for example, encrption/decryption, get IP. As a PHP developer, you should have a list of the handy functions in your toolkit so that you can pick up in every project you work on. Here is a summary of some handy PHP functions. 1. PHP encryption/decryption Encryption/decryption can be used when storing user confidential information such as passwords. Below function uses base64 and MD5 to accomplish encryption/decry...

   PHP,function,real IP,SQL injection     2014-12-06 08:46:08

  What you may not know about PHP session

When we access one website, the site usually should have a mechanism to keep track of the status of the user on the site. There are a few mechanisms supported by many server side languages to help track user status such as session and cookie. Today we will talk about session, when creating a session, we need to keep track of many data, besides user data, we also need to tell the server what is the timeout of the session so that we can garbage collect the session data which should not be stored a...

   PHP session,session timeout,example     2013-07-06 08:44:18

  System programming is still there

System programming is the practice of writing system software. System software lives at a low level, interfacing directly with the kernel and core system libraries. Your shell and your text editor, your compiler and your debugger, your core utilities and system daemons are all system software. But so are the network server, the web server, and the database. These components are entirely system software, primarily if not exclusively interfacing with the kernel and the C library. But nowadays more...

   System programming     2014-02-27 05:46:48

  Send email using PHPMailer on GoDaddy hosting

According to PHPMailer troubleshooting guide, GoDaddy has a very strict rule on sending email using PHPMailer. Popular US hosting provider GoDaddy imposes very strict (to the point of becoming almost useless) constraints on sending an email. They block outbound SMTP to ports 25, 465 and 587 to all servers except their own. This problem is the subject of many frustrating questions on Stack Overflow. If you find your script works on your local machine, but not when you upload it to GoDaddy, ...

   PHP,PHPMAILER,GODADDY     2018-11-16 08:28:55

  How to do pprof for gRPC service

gRPC is a RPC framework based on HTTP and is frequently used for communications among micro service inside the same organization network. However,  the service functions cannot be accessed via normal HTTP URL as it's not a WEB framework. In this case, how to do pprof on a gRPC service? The trick is starting a HTTP server asynchronously while starting the gRPC service. This HTTP server can be accessed to run prrof debug. go func(){ http.ListenAndServe(":10001", nil) }() Since it uses the de...

   GOLANG,PPROF,GRPC     2021-01-29 23:11:33

  Roundup on Parallel Connections

A lot of blogging and follow-up discussion ensued with the announcement that IE8 supports six connections per host. The blogs I saw: IE8: The Performance Implications IE8 speeds things up IE8: 6 Connections Per Host IE 8 and Performance Testing IE8.s Connection Parallelism IE 8 Connection Parallelism Issues It’s likely that Firefox 3 will support 6 connections per server in an upcoming beta release, which means more discussion is expected. I wanted to pull all the facts into one place an...

   Browser,Concurrent connection,Persistent     2011-09-05 01:51:44