我需要一种快速方法来查明给定端口是否已使用 Ruby 打开。我目前正在摆弄这个：
require 'socket'
def is_port_open?(ip, port)
begin
TCPSocket.new(ip, port)
rescue Errno::ECONNREFUSED
return false
end
return true
end
如果端口打开，它会很好用，但这样做的缺点是，有时它会等待 10-20 秒，然后最终超时，抛出
ETIMEOUT是否可以将此代码修改为仅等待一秒钟（如果到那时我们什么也没得到，则返回
false编辑： 调用 bash 代码也是可以接受的，只要它可以跨平台工作（例如，Mac OS X、*nix 和 Cygwin），尽管我更喜欢 Ruby 代码。
像下面这样的东西可能会起作用：
require 'socket'
require 'timeout'
def is_port_open?(ip, port)
begin
Timeout::timeout(1) do
begin
s = TCPSocket.new(ip, port)
s.close
return true
rescue Errno::ECONNREFUSED, Errno::EHOSTUNREACH
return false
end
end
rescue Timeout::Error
end
return false
end
所有其他现有答案都是不可取的。使用
TimeoutSocket.tcp("www.ruby-lang.org", 10567, connect_timeout: 5) {}
对于较旧的 ruby，我能找到的最好方法是使用非阻塞模式，然后
select更多 Ruby 惯用语法：
require 'socket'
require 'timeout'
def port_open?(ip, port, seconds=1)
Timeout::timeout(seconds) do
begin
TCPSocket.new(ip, port).close
true
rescue Errno::ECONNREFUSED, Errno::EHOSTUNREACH
false
end
end
rescue Timeout::Error
false
end
我最近想出了这个解决方案，利用unix
lsofdef port_open?(port)
!system("lsof -i:#{port}", out: '/dev/null')
end
为了完整起见，Bash 应该是这样的：
$ netcat $HOST $PORT -w 1 -q 0 </dev/null && do_something
-w 1-q 0stdinEOF/dev/nullBash 也有自己的内置 TCP/UDP 服务，但它们是编译时选项，我没有用它们编译的 Bash :P
我的解决方案源自发布的解决方案。
require 'socket'
def is_port_open?(ip, port)
begin
s = Socket.tcp(ip, port, connect_timeout: 5)
s.close
return true
rescue => e
# possible exceptions:
# - Errno::ECONNREFUSED
# - Errno::EHOSTUNREACH
# - Errno::ETIMEDOUT
puts "#{e.class}: #{e.message}"
return false
end
end
我对克里斯·赖斯的回答略有不同。仍然可以处理单次尝试超时的情况，但也允许多次重试，直到您放弃。
def is_port_open?(host, port, timeout, sleep_period)
begin
Timeout::timeout(timeout) do
begin
s = TCPSocket.new(host, port)
s.close
return true
rescue Errno::ECONNREFUSED, Errno::EHOSTUNREACH
sleep(sleep_period)
retry
end
end
rescue Timeout::Error
return false
end
end
所有 *nix 平台：
尝试如下 nc / netcat 命令。
`nc -z -w #{timeout_in_seconds} -G #{timeout_in_seconds} #{host} #{port}`
if $?.exitstatus == 0
#port is open
else
#refused, port is closed
end
-z 标志可用于告诉 nc 报告开放端口，而不是启动连接。
-w 标志表示连接和最终网络读取超时
-G 标志是连接超时（以秒为单位）
使用 -n 标志来处理 IP 地址而不是主机名。
示例：
# `nc -z -w 1 -G 1 google.com 80`
# `nc -z -w 1 -G 1 -n 123.234.1.18 80`
很久没有关注这个问题了，但这是我用来查看某个端口是否正在侦听的脚本。请注意，我在已接受的答案中建议的方法并未使用。
#!/usr/bin/env ruby
# encoding: ASCII-8bit
# warn_indent: true
# frozen_string_literal: true
# rubocop:disable Lint/MissingCopEnableDirective
# rubocop:disable Style/StderrPuts
# Test a connection to a port on a host. A host name, IPv4 address, or IPv6
# address is allowed for the host. A service name or a port number is allowed
# for the port.
# Trap a few signals and exit. No problem if the operating system doesn't
# support one of the signals. Rescuing ArgumentError takes care of that.
%w[HUP INT PIPE QUIT TERM].each do |signame|
Signal.trap(signame) do
$stdout.puts
exit 1
end
rescue ArgumentError
# the operating system doesn't support the signal, try the next list element
end
require 'socket'
def usage
me = File.basename($PROGRAM_NAME)
$stderr.puts "usage: #{me} [-v] host_name_or_address service_name_or_port_number"
$stderr.puts " or: #{me} [-v] host_name_or_address:service_name_or_port_number"
exit 1
end
# address family to string or nil
def af_to_s(addr)
if addr.ipv4?
'IPv4'
elsif addr.ipv6?
'IPv6'
end
end
# VERY simple command line argument handling follows...
verbose = if ARGV[0] == '-v'
ARGV.shift
true
else
false
end
case ARGV.size
when 1
if ARGV[0] =~ /^(.*):([^:]+)$/
host = Regexp.last_match(1)
port = Regexp.last_match(2)
else
usage
end
when 2
host, port = *ARGV
else
usage
end
host = host.strip # get thawed copy of host with white space removed
port = port.strip # get thawed copy of port with white space removed
host = Regexp.last_match(1) if host =~ /^\[(.*)\]$/
usage if host.empty? || port.empty?
begin
addrs = Addrinfo.getaddrinfo(host, port, nil, :STREAM, nil, Socket::AI_ALL)
rescue SocketError => e
$stderr.puts "error: host #{host}: #{e}"
exit 2
end
if addrs.empty? # can this ever happen?
$stderr.puts "error: host #{host}: getaddrinfo failed to return anything!"
exit 3
end
num_conn = 0
num_addrs = 0
addrs.each do |addr|
family = af_to_s(addr)
next if family.nil? # not an IPv4 or IPv6 address
num_addrs += 1
# Get an IPv4 or IPv6 socket (which is determined by the address family).
s = Socket.new(addr.afamily, Socket::SOCK_STREAM)
# Connect in non-blocking mode. If the connection can be made immediately,
# then skip the select() call. If the connection can't be made immediately,
# then use select() to wait up to 10 seconds for the connection to be
# allowed. If select() times out, then just go on to the next address.
begin
s.connect_nonblock(addr.to_sockaddr)
rescue Errno::EINPROGRESS
next if IO.select(nil, [s], nil, 10).nil?
begin
# Socket is ready. Attempt real connection.
s.connect_nonblock(addr.to_sockaddr)
rescue Errno::EISCONN
# connected
rescue Errno::ECONNREFUSED => e
$stderr.puts "error: #{e}" if verbose
next
rescue SystemCallError => e
$stderr.puts "error: #{e}" if verbose
next
end
rescue Errno::ENETUNREACH => e
$stderr.puts "error: #{e}" if verbose
next
end
puts "connected #{family} #{host}"
num_conn += 1
end
if num_addrs.zero?
$stderr.puts "error: no IPv4 or IPv6 addresses found for #{host}"
exit 4
elsif num_conn.zero?
$stderr.puts 'error: all connections failed'
exit 5
else
exit 0
end