code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you under the Apache License, Version 2.0 (the
  // "License"); you may not use this file except in compliance
  // with the License.  You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing,
  // software distributed under the License is distributed on an
  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  package org.openqa.selenium.net;
  
  import java.io.BufferedReader;
  import java.io.File;
  import java.io.IOException;
  import java.io.Reader;
  import java.io.StringReader;
  import java.io.UncheckedIOException;
  import java.nio.charset.Charset;
  import java.nio.file.Files;
  
  public class LinuxEphemeralPortRangeDetector implements EphemeralPortRangeDetector {
  
    private final int firstEphemeralPort;
    private final int lastEphemeralPort;
  
    public static LinuxEphemeralPortRangeDetector getInstance() {
      File file = new File("/proc/sys/net/ipv4/ip_local_port_range");
      if (file.exists() && file.canRead()) {
        try (Reader inputFil = Files.newBufferedReader(file.toPath(), Charset.defaultCharset())) {
          return new LinuxEphemeralPortRangeDetector(inputFil);
        } catch (IOException e) {
          throw new UncheckedIOException(e);
        }
      }
      return new LinuxEphemeralPortRangeDetector(new StringReader("49152 65535"));
    }
  
    LinuxEphemeralPortRangeDetector(Reader inputFil) {
      FixedIANAPortRange defaultRange = new FixedIANAPortRange();
      int lowPort = defaultRange.getLowestEphemeralPort();
      int highPort = defaultRange.getHighestEphemeralPort();
      try (BufferedReader in = new BufferedReader(inputFil)) {
        String[] split = in.readLine().split("\\s+", 3);
        lowPort = Integer.parseInt(split[0]);
        highPort = Integer.parseInt(split[1]);
      } catch (IOException | NullPointerException ignore) {
      }
      firstEphemeralPort = lowPort;
      lastEphemeralPort = highPort;
    }
  
    @Override
    public int getLowestEphemeralPort() {
      return firstEphemeralPort;
    }
  
    @Override
    public int getHighestEphemeralPort() {
      return lastEphemeralPort;
    }
  }
  