Enable --transparent mode for docker

Dockerfile

@@ -1,26 +1,22 @@
 FROM alpine:latest as build
 
 WORKDIR /sslh
-
 COPY . /sslh
-RUN \
-  apk add \
-    gcc \
-    libconfig-dev \
-    make \
-    musl-dev \
-    pcre2-dev \
-    perl && \
-  make sslh-select && \
-  strip sslh-select
+
+RUN apk add gcc libconfig-dev make musl-dev pcre2-dev perl
+RUN make sslh-select && strip sslh-select
 
 FROM alpine:latest
 
 COPY --from=build "/sslh/sslh-select" "/usr/local/bin/sslh"
 
-RUN apk --no-cache add libconfig pcre2
+RUN apk --no-cache add libconfig pcre2 iptables ip6tables libcap
+
+RUN adduser sslh --shell /bin/sh --disabled-password
+RUN setcap cap_net_bind_service,cap_net_raw+ep /usr/local/bin/sslh
 
 COPY "./container-entrypoint.sh" "/init"
 ENTRYPOINT [ "/init" ]
 
-USER nobody:nogroup
+# required for updating iptables
+USER root:root