在中國大陸，包括上海，由於政府的網路審查制度（俗稱「防火長城」或GFW），許多海外社交媒體與即時通訊軟體如Facebook、LINE、Instagram、X（原Twitter）和YouTube等無法直接使用。若想要在當地使用這些平台，通常需要借助一些「翻牆」手段，也就是繞過網路封鎖。常見的方法包括使用VPN（虛擬私人網路）、代理伺服器、V2Ray、Shadowsocks等技術。

VPN是最普遍的方式。透過VPN服務，使用者可以將自己的網路連線加密並導向海外伺服器，從而繞過中國的網路限制。這些工具的原理是建立一條虛擬通道，使使用者看似從境外訪問網站。不過，中國對VPN的管控越來越嚴格，許多免費或小型VPN經常被封鎖，導致連線不穩或速度緩慢。雖然仍有部分收費VPN（如ExpressVPN、NordVPN、Surfshark）提供較穩定的服務，但用戶可能需要事先在出國前下載安裝，因為這些軟體在中國境內往往無法正常下載。此外，使用 VPN在法律上存在灰色地帶，雖然個人使用通常不會被追究，但商業用途則可能觸法。

另一種方式是使用基於Shadowsocks或V2Ray的私人伺服器，這些工具技術上比傳統VPN更靈活，容易規避GFW的監測，但缺點是設定相對複雜，需要基本網路知識才能自行搭建和維護，並非所有一般使用者都能輕易操作。此外，這類工具如果被GFW發現 IP，也仍可能遭到封鎖。也有一些中國網民使用瀏覽器插件或境外雲端代理進行臨時連線，例如透過特定的加密網頁代理進入封鎖網站，但這些方法的速度與穩定性都不理想，且安全性較低，資料容易被攔截或洩漏。

從使用者角度來說，若只是短期旅行或偶爾需要使用臉書、LINE等服務，建議選擇市面上評價較佳、可在出國前安裝好的付費VPN服務或是使用海外漫遊就可顧穩定與安全。如果是長期居住或有高頻率需求，則可考慮自行搭建穩定的代理伺服器，但需要定期維護與調整配置。

需要注意的是，即使成功翻牆，也可能會因網速限制或伺服器延遲影響使用體驗，而且在公共Wi-Fi環境下翻牆操作存在資訊安全風險，建議開啟雙重驗證、避免登入敏感帳號並使用加密連線，保護個資安全。

In mainland China, including cities like Shanghai, many overseas social media and instant messaging platforms such as Facebook, LINE, Instagram, X (formerly Twitter), and YouTube are not directly accessible due to the government's internet censorship system, commonly referred to as the "Great Firewall" or GFW. To access these platforms while in China, users typically rely on "circumvention" methods to bypass the restrictions. The most common techniques include the use of VPNs (Virtual Private Networks), proxy servers, V2Ray, and Shadowsocks.

VPNs are the most widely used method. With a VPN service, users can encrypt their internet traffic and route it through servers located abroad, effectively bypassing Chinese internet controls. These tools work by creating a secure virtual tunnel, making it appear as if the user is accessing the internet from outside China. However, VPN usage is increasingly regulated in China, and many free or small-scale VPNs are frequently blocked, resulting in unstable connections or slow speeds. Some paid VPNs such as ExpressVPN, NordVPN, and Surfshark still offer relatively stable services, but they often need to be downloaded and installed before entering China, as VPN software websites are usually inaccessible from within the country. Legally, using VPNs exists in a gray area—personal use is generally tolerated, but using them for business purposes could potentially violate local laws.

Another option involves setting up a private server based on Shadowsocks or V2Ray. These tools are more flexible than traditional VPNs and are better at evading GFW detection. However, they require more technical knowledge to configure and maintain, making them less accessible to casual users. Additionally, if the IP address of such tools is detected by the GFW, they may still be blocked.

Some Chinese users also resort to browser extensions or cloud-based proxies for temporary access, such as using encrypted web proxies to visit blocked sites. However, these methods often suffer from poor speed and reliability, and their security is generally low, increasing the risk of data interception or leakage.

From a user’s perspective, if you are only traveling short-term or need occasional access to platforms like Facebook or LINE, it is recommended to use a well-reviewed paid VPN that can be installed in advance or rely on international data roaming services, which tend to offer more stability and security. For long-term residents or users with frequent access needs, setting up a personal proxy server may be a more sustainable solution, although it requires regular maintenance and configuration updates.

It is important to note that even with a successful circumvention setup, the user experience may still be affected by bandwidth limits or server latency. Furthermore, using these tools over public Wi-Fi poses cybersecurity risks. Therefore, it is strongly advised to enable two-factor authentication, avoid logging into sensitive accounts, and use encrypted connections to safeguard personal information.