Is it possible to redirect traffic through an external proxy?

Is it possible to redirect traffic through an external proxy server so that clients will not have to manually configure the proxy?

Client ===> Router ===> External Proxy ===> Router ===> Client

The short answer is 'no'.

Transparent proxies are only possible for plain unencrypted http, but not for https connections, which make up over 95% of today's internet use.

Yes, but I do not plan to intercept any traffic, I just want to route it through an external server like how squid proxy does it.

squid is available in openwrt ...

My router doesn't have enough space to install squid, that's why I installed squid in a different server.

SNIproxy, but

  • it's not available in openwrt, you'd have to build it yourself
  • only proxies HTTP/S
  • SNI header is about to get encrypted, too

Is there a different alternative?

have a look at sslh, and perhaps haproxy

yes it is possible. to some extent.

  1. you can use WPAD.
  2. you can use DHCP option 252.

both works on OS level, nevertheless it does not mean all client must respect it. so at least you should make sure web browsers using system proxy or auto detect setting.

With some tweaking of squid.conf and Make, you should be able to run squid with 64MB RAM, assuming minimal openwrt and no caching, of course.