Hello,
I have 3 internal networks: 192.168.1.0/24 - 192.168.2.0/24 - 192.168.3.0/24 and set up a Squid proxy at another machine. I put the machine on the internet side whit a external ip, all seems to be alright....everything works but when I try to redirect de petitions to port 80 from the internal net to the external proxy in port 3128 a loose it.....cant navigate, but the proxy is working and accepting connections...try some rules in the firewall but nothing works. Please some help here. Resume: redirect all the petitions from the internal net at port 80 to the external proxy port 3128.

Tnks and sorry for my english.

Testing

use dst-nat with a redirect action to solve this issue

yes......I do that....the rule was
src-address=0.0.0.0/0:0-65535 in-interface=ether1
dst-address=:80 protocol=tcp icmp-options=any:any flow="" limit-count=0 limit-burst=0
limit-time=0s action=redirect to-dst-address="external ip" to-dst-port=3128

That's in 2.8 version, today im going to change to 2.9.

Regards AND HELPPPPP

Action redirect will only redirect to the router's local port - it will ignore the to-address field.
If you want to redirect the all proxy requests to external proxy then you should enable the web-proxy support on the RouterOS and use parent-proxy argument.

But if I activate the internal proxy there is some lag.......I can use the web proxy to redirect transparently whitout the mikrotik trying to do cache or something???
I want to go directly to the external proxy and don't want the mikrotik to process the data.

Not-a-bug. source nat looses destination IP address of the request, so the proxy does not know what page do you want to open. local proxy gets that information through internal kernel calls, but there is no way external proxy to know that information. Use local proxy on MT router and configure it to use your external proxy as a parent proxy