HTTP_PROXY URL of the proxy to use for HTTP requests. The
document part is ignored. Only HTTP proxies are
supported for HTTP requests. If no port number
is specified, the default is 3128.
Note that this proxy will also be used for FTP
documents, unless the FTP_PROXY variable is set.
I knew that and thought so, BUT it is troublesome to set all applications. Further, in macOS, there is a SOCKS proxy settings in the Network system preferences which is universal to the entire OS. And so therefore I thought FreeBSD can do the same. It'll be so much convenient if this is possible.You don't. It's an application specific setting. Not all applications are able to use a SOCKS5 proxy.
proxychains firefox
from the command line. $ tsocks <window manager>
[forward-socks]
sni = socks
client = yes
protocol = socks
accept = localhost:1080
connect = IP.RE.MO.TE:https
ipfw nat $nat config if $nat_if reset same_ports
ipfw add set $set nat $nat all from any to any via $nat_if
ipfw add set $set fwd 127.0.0.1,1080 tcp from any to any out via $nat_if
[TLS]
client = no
accept = https
transparent = source
connect = localhost:http
[socks]
client = no
sni = TLS:socks
protocol = socks
transparent = none
;transparent = source
ipfw add fwd IP.RE.MO.TE,443 tcp from 127.0.0.1 443 to any