On Linux, there are several alternative apps to ProxyCap that you can use to redirect network traffic through a proxy server. Here are some options:

1. Proxychains: Proxychains is a command-line tool that allows you to redirect any TCP connection through a proxy server. It supports HTTP, SOCKS4, and SOCKS5 proxies, and is compatible with most Linux distributions.

2. Redsocks: Redsocks is a transparent proxy redirector that intercepts TCP connections and redirects them through a SOCKS5 or HTTP proxy server. It can be installed on most Linux distributions and supports both IPv4 and IPv6.

3. Privoxy: Privoxy is a web proxy with advanced filtering capabilities that can be used to redirect traffic through a proxy server. It supports HTTP, SOCKS4, and SOCKS5 proxies and can be configured to block ads, track-ers, and other unwanted content.

4. Polipo: Polipo is a caching web proxy that can be used to redirect traffic through a proxy server. It supports HTTP and SOCKS4 proxies and can be installed on most Linux distributions.

These are just a few examples of alternative apps to ProxyCap on Linux. There are many other options available, depending on your specific needs and preferences.