Add mss clamping

Dockerfile

@@ -18,6 +18,8 @@ RUN CGO_ENABLED=0 GOOS=linux go build -o /gerbil
 # Start a new stage from scratch
 FROM ubuntu:22.04 AS runner
 
+RUN apt-get update && apt-get install -y iptables iproute2 && rm -rf /var/lib/apt/lists/*
+
 # Copy the pre-built binary file from the previous stage and the entrypoint script
 COPY --from=builder /gerbil /usr/local/bin/
 COPY entrypoint.sh /