[手动选题][tech]: 20230315.1 ⭐️ How to know if You are Behind a Proxy Server.md

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+[#]: subject: "How to know if You are Behind a Proxy Server?"
+[#]: via: "https://itsfoss.com/check-proxy-server/"
+[#]: author: "Sreenath https://itsfoss.com/author/sreenath/"
+[#]: collector: "lkxed"
+[#]: translator: " "
+[#]: reviewer: " "
+[#]: publisher: " "
+[#]: url: " "
+
+How to know if You are Behind a Proxy Server?
+======
+
+**What is a proxy?**
+
+A proxy is a server or software application that acts as an intermediary between a client and another server. It serves as a gateway between the client and the internet and allows users to access online resources while keeping their identity, location, and other personal information hidden.
+
+Proxies are often used to enhance security, privacy, and add filters/firewall to your network.
+
+There are several types of proxies like HTTP Proxy, SOCKS Proxy, Transparent Proxy, etc.
+
+Unless you are behind a transparent proxy, it is effortless to check. Here, I shall discuss methods to detect both the transparent proxy and the usual proxies in use.
+
+### How to check if you are behind a Transparent proxy
+
+While each type of proxy has its features and functionalities, if it's a transparent proxy, you won't be able to detect it on the client's PC. This is because the transparent proxy operates silently in the background, intercepting all traffic without modifying it.
+
+Occasionally, it could be your internet service provider and the Content Delivery Networks that use these to cache a copy of a resource to save bandwidth on their end or just to monitor/filter the network.
+
+There are several ways to check if you are behind a transparent proxy:
+
+- **The IP address obtained through some online IP detect/check websites may not match the IP address of your computer or device.** Because the proxy server is intercepting your traffic and sending it out with its IP address.
+- **Check your network settings to see if there is a proxy server configured.**
+- **Take the help of some online Proxy detection tools.**
+- **Connect to a server that you know does not exist.** If the error displayed on the webpage looks different from usual, you might be behind a proxy.
+
+Whether you like it or not, you can always bypass the transparent proxy using a [VPN service][1].
+
+### How to check if you are behind a proxy on Ubuntu
+
+Ubuntu, or any other Linux distribution, offers several ways to check this. Here, Ubuntu 22.10 running GNOME is used for the purpose.
+
+#### Using GNOME Settings
+
+This is the straightforward GUI way. Open the GNOME settings and go to the Networks tab and press the gear icon, adjacent to it.
+
+![Select the gear icon adjacent to the Network proxy section][2]
+
+It should be **off by default**.
+
+If you are behind a proxy, you can get a different status here. Inside the proxy settings, you can see that, I am using a proxy here (manually configured).
+
+![Proxy details in GNOME Settings][3]
+
+The same status of proxies can be changed using the gsettings command in GNOME DE.
+
+```
+gsettings set org.gnome.system.proxy mode 'none'
+```
+
+You can replace the `none` with `auto` or `manual`. Remember that, this setting is temporary and only for the current user.
+
+#### Using the Command line
+
+You can get the status of proxies through the command line in various ways.
+
+**Getting the status of the proxy by listing the associated environment variables**
+
+Open a terminal and run either of the following commands:
+
+```
+env | grep -i proxy
+```
+
+```
+cat /etc/environment | grep -i proxy
+```
+
+```
+set | grep -i proxy
+```
+
+![Using set command to check Proxy variables][4]
+
+An empty output means that, there are no proxies configured. Else, it will print the relevant ENV variables.
+
+🚧
+
+Note that this will work if you set the proxy as an environment variable.
+
+Alternatively, you can echo each proxy variable to check whether that particular one is set.
+
+Here's what you can type in the terminal:
+
+```
+echo $http_proxy
+```
+
+**Check using nmcli command**
+
+Open a terminal and issue the command:
+
+```
+nmcli connection show
+```
+
+![List all the connections using nmcli command][5]
+
+This will list your connections and the associated UUID numbers. Note the UUID number of the connection, you want to check. Then use the command:
+
+```
+nmcli connection show <UUID or name> | grep -i "proxy"
+```
+
+This will list the variables, where, you can note the proxy server and the port.
+
+![Proxy details using nmcli command][6]
+
+### Wrapping Up
+
+I hope this guide helps you know if you are behind a proxy.
+
+I must mention that **not all proxy configurations are malicious.**
+
+However, it is important to know whether your system has a proxy configured or not.
+
+--------------------------------------------------------------------------------
+
+via: https://itsfoss.com/check-proxy-server/
+
+作者：[Sreenath][a]
+选题：[lkxed][b]
+译者：[译者ID](https://github.com/译者ID)
+校对：[校对者ID](https://github.com/校对者ID)
+
+本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
+
+[a]: https://itsfoss.com/author/sreenath/
+[b]: https://github.com/lkxed/
+[1]: https://itsfoss.com/best-vpn-linux/
+[2]: https://itsfoss.com/content/images/2023/02/select-the-gear-icon-adjacent-to-proxy.png
+[3]: https://itsfoss.com/content/images/2023/02/Proxy-in-GNOME-settings.png
+[4]: https://itsfoss.com/content/images/2023/02/set_grep_proxy.png
+[5]: https://itsfoss.com/content/images/2023/02/nmcli-connection-show.png
+[6]: https://itsfoss.com/content/images/2023/02/proxy-using-nmcli.png