Сборка:

git clone https://github.com/z3APA3A/3proxy
cd 3proxy
echo "#define  ANONYMOUS" >> src/proxy.h
make -f Makefile.Linux all install
cp ./scripts/init.d/3proxy.sh /etc/init.d/3proxy
chmod 750 /etc/init.d/3proxy
update-rc.d 3proxy defaults
mkdir /etc/3proxy
cp ./scripts/3proxy.cfg /etc/3proxy/3proxy.cfg
useradd  --system --shell /sbin/nologin --comment "3proxy daemon" --user-group proxy

Пример конфига /etc/3proxy/3proxy.cfg :

#!/usr/local/bin/3proxy
# Yes, 3proxy.cfg can be executable, in this case you should place
# something like
#config /usr/local/3proxy/3proxy.cfg
# to show which configuration 3proxy should re-read on realod.

system "echo Hello world!"
# you may use system to execute some external command if proxy starts
# We can configure nservers to avoid unsafe gethostbyname() usage
nserver 1.1.1.1
nserver 8.8.8.8
# nscache is good to save speed, traffic and bandwidth
nscache 65536
#nsrecord porno.security.nnov.ru 0.0.0.0
# nobody will be able to access porno.security.nnov.ru by the name.
#nsrecord wpad.security.nnov.ru www.security.nnov.ru
# wpad.security.nnov.ru will resolve to www.security.nnov.ru for
# clients

timeouts 1 5 30 60 180 1800 15 60
# Here we can change timeout values

#CL - clear password
#CR - hash from password
#openssl passwd -1
users "3APA3A:CL:3apa3a"
users "3APA3A:CR:$1$k8yR8LAH$eYLuJch.BFjhoAWxurWye/"
daemon
log /var/log/3proxy.log D
archiver gz /bin/gzip %F
rotate 30
# We will keep last 30 log files
# public ipv4 
external A.B.C.D
# external is address 3proxy uses for outgoing connections. 0.0.0.0 means any
# interface. Using 0.0.0.0 is not good because it allows to connect to 127.0.0.1
#internal ipv4 can be the same as external
internal A.B.C.D
# internal is address of interface proxy will listen for incoming requests
# 127.0.0.1 means only localhost will be able to use this proxy. This is
# address you should specify for clients as proxy IP.
# You MAY use 0.0.0.0 but you shouldn't, because it's a chance for you to
# have open proxy in your network in this case.
##############################################
################### Web ######################
##############################################
auth strong
# We want to protect internal interface
# deny * * 127.0.0.1,192.168.1.1
# and llow HTTP and HTTPS traffic.
#allow * * * 80-88,8080-8088 HTTP
#allow * * * 443,8443 HTTPS
allow 3APA3A
proxy -p12345 -n -a
######################################
############## Socks  ##################
######################################
auth strong
# auth none
flush
allow 3APA3A
maxconn 128
socks -p23456
#UID of user "proxy" is 13
setgid 13
setuid 13

В приведенном конфиге 3proxy запускает HTTP(s) и SOCK5 proxy на портах 12345 и 23456 соответственно.