/
ephemeral_ports_linux.go
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/
ephemeral_ports_linux.go
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//go:build linux
// +build linux
// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License"). You may
// not use this file except in compliance with the License. A copy of the
// License is located at
//
// http://aws.amazon.com/apache2.0/
//
// or in the "license" file accompanying this file. This file 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 utils
import (
"bufio"
"fmt"
"os"
)
const (
// portRangeKernelParam is a kernel parameter that defines the ephemeral port range
portRangeKernelParam = "/proc/sys/net/ipv4/ip_local_port_range"
// DefaultPortRangeStart indicates the first port in ephemeral port range
DefaultPortRangeStart = 49153
// DefaultPortRangeEnd indicates the last port in ephemeral port range
DefaultPortRangeEnd = 65535
)
// GetDynamicHostPortRange returns the ephemeral port range defined by the "/proc/sys/net/ipv4/ip_local_port_range"
// kernel parameter. Ref: https://github.com/moby/moby/blob/master/libnetwork/portallocator/portallocator_linux.go
func GetDynamicHostPortRange() (start int, end int, err error) {
file, err := os.Open(portRangeKernelParam)
if err != nil {
return 0, 0, err
}
defer file.Close()
n, err := fmt.Fscanf(bufio.NewReader(file), "%d\t%d", &start, &end)
if n != 2 || err != nil {
if err == nil {
err = fmt.Errorf("unexpected count of parsed numbers (%d)", n)
}
return 0, 0, fmt.Errorf("failed to parse ephemeral port range from %s: %v",
portRangeKernelParam, err)
}
return start, end, nil
}