微信号:dellemc_tech

介绍:为戴尔易安信客户提供技术支持服务,为广大IT行业用户分享技术文章与行业信息。

网络基本功(二十八):Wireshark抓包实例分析HTTP问题(下)

2017-08-09 20:40 EMC中国技术社区

Client errors:

                                                                         

 

Code

 
 

Status

 
 

Explanation

 
 

What    to do

 

400

Bad   request

The   request could not be understood by the server due to a syntax problem.   The request should be modified by the client before resending to it.

Check the   website address. This can also happen due to a site error.

401

Authorization   required

The   client is denied access due to the lack of authentication codes.

Check   your username and password.

402

Payment   required

Reserved   for future use.


403

Forbidden

The   client is not allowed to see a specific file. This can be due to the server   access limit.

Check the   credentials. Also, there are fewer chances that the server is loaded.

404

Not found

The   requested resource could not be found.

This can   be because the resource was deleted, or it never existed before. It can also   be due to URL misspellings.

405

Method   not allowed

The   method you are using to access the file is not supported or not allowed by   the resource.


406

Not   acceptable

Content   generated by the resource is not acceptable according to the client request.

Check/update   your browser.

407

Proxy   authentication required

Request   authentication is required before it can be performed.

The   client must first authenticate itself with the proxy.

408

Request   timed out

It took   the server longer than the allowed time to process the request.

Check   response time and load on the network.

409

Conflict

The   request submitted by the client cannot be completed because it   conflicts with some established rules.

Can be   because you try to upload a file that is older that the existing one or   similar problems. Check what the client is trying to do.

410

Gone

The URL   requested by the client is no longer available from that system.

Usually   this is a server problem. It can be due to a file that was deleted or   location was forwarded to a new location.

411

Content   length required

The   request is missing itsContent-Length header.

Compatibility   issue on a website. Change/update your browser.

412

Precondition   failed

The   client has not set up a configuration that is required for the file to be   delivered.

Compatibility   issue on a website. Change/update your browser.

413

Request   entity too long

The   requested file was too big to process.

Server   limitation.

414

Request   URI too long

The   address you entered was overly long for the server.

Server   limitation.

415

Unsupported   media type

The file   type of the request is not supported.

Server   limitation.

 

 

以下示例是一个简单的客户端报错。按照以下步骤进行操作:

  1. 右键有报错的报文。

  2. 选择Follow TCP stream,会看到以下窗口:

   3.  显示以下内容:

  • 客户端尝试浏览URI/poker-client/broadcast.htm(如截屏中1和3所示)

  • URI通过http://www.888poker.com/poker-client/promotions.htm转发(截屏中2所示)

  • 状态码为404 Not Found(如截屏中4所示)

 


Client errors:

                                 

 

Code

 
 

Status

 
 

Explanation

 
 

What    to do

 

500

Internal   server error

The web   server encountered an unexpected condition that prevented it from   carrying out the client request for access to the requested URL.

Response   that is usually caused by a problem in your Perl code when a CGI program is   run.

501

Not   implemented

The   request cannot be executed by the server.

A server   problem.

502

Bad   gateway

The   server you're trying to reach is sending back errors.

A server   problem.

503

Service   unavailable

The   service or file that is being requested is not currently available.

A server   problem.

504

Gateway   timeout

The   gateway has timed out. This message is like the 408 timeout   error, but this one occurs at the gateway of the server.

Server is   down or nonresponsive.

505

HTTP   version not supported

The HTTP   protocol version that you want to use for communicating with the server is   not supported by it.

Server   does not support the HTTP version.

 

服务器不可用(错误代码503)可能有多种原因。以下示例是一个小办公室碰到的问题:员工能够访问Facebook,但当他们点击站点上的链接,则显示页面被拦截。以下截屏中,可看出页面被防火墙拦截:

 


工作原理:

标准的HTTP浏览模式如下:

  1. TCP打开连接(三路握手信号)

  2. HTTP发送GET命令

  3. 数据下载到浏览器

 

在一个网页打开多个连接的情况下(大多数网页都是如此)。每个连接需要一个DNS 查询,响应,TCP SYN-SYN/ACK-ACK,以及HTTP GET。之后数据才会出现在显示屏上。

 

当你在packet detail面板没有看到显示内容时,右键报文并选择Follow TCP stream,会看到连接的细节数据。另一个广泛应用的工具是Fiddler,Fiddler是HTTP故障排查的免费工具。




其它参考文章:

【网络基本功】细说网络那些事儿



更多精彩内容,请点击阅读原文”进行查看!

如何每天都能收到如此精彩的文章?

①点击右上角点击查看官方账号”→点击关注

②长按并识别下图中的二维码,直接访问EMC中文支持论坛


 
戴尔易安信技术支持 更多文章 这部看哭无数人的电影让小编想到一个词——Unity 老板让我干完这个月就辞职 特大号这篇文章让万千售前沸腾啦 VxRail打好基础,未来6000个VDI也毫不惧怕 三位20多年的IT老兵在聊存储,干货多,速来!
猜您喜欢 传统的 8 小时工作制为什么会效率低下? 小道问答 (2015 第四季) 80秒腾讯开工刷红包.avi 「黄泽瑄的成长记」第六季来啦 微软推出.NET Core与ASP.NET漏洞奖励计划