Dns.GetHostAddress和Dns.GetHostEntry都只返回ipv4地址。我如何获得ipv4和ipv6地址？
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一个类似的问题已经被问到here和here和here，但没有一个答案似乎有效，所以我发布实际代码并显示它在支持ipv6的机器上运行，希望有人可以提出解决方案
这是从这两个问题中获取的代码
using System;
public class HelloWorld
{
static public void Main ()
{
string hostName = "google.com"; // uri.DnsSafeHost;
Console.WriteLine("DNS.GetHostAddresses: " + hostName);
var hostAddresses = System.Net.Dns.GetHostAddresses(hostName);
Console.WriteLine("DNS.NumAddreses:" + hostAddresses.Length);
foreach (System.Net.IPAddress hostAddress in hostAddresses)
{
Console.WriteLine(
"addr: " + hostAddress.ToString() +
" family: " + hostAddress.AddressFamily.ToString());
}
System.Net.IPHostEntry ipHostEntry = System.Net.Dns.GetHostEntry(hostName);
Console.WriteLine("DNS.GetHostEntry NumAddresses:" + ipHostEntry.AddressList.Length);
foreach (System.Net.IPAddress hostAddress in ipHostEntry.AddressList)
{
Console.WriteLine(
"addr: " + hostAddress.ToString() +
" family: " + hostAddress.AddressFamily.ToString());
}
}
}
我正在使用ipv6在Ubuntu 14.04上运行它。这是一些可能相关的信息
# ip -6 addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
inet6 2400:6180:0:d0::691:9001/64 scope global
valid_lft forever preferred_lft forever
inet6 fe80::601:eeff:fe7e:201/64 scope link
valid_lft forever preferred_lft forever
Google.com证明有一个ipv6地址
# dig google.com AAAA +short
2404:6800:4003:c00::8a
显示我可以直接在其ipv6地址ping google.com
# ping6 2404:6800:4003:c00::8a
PING 2404:6800:4003:c00::8a(2404:6800:4003:c00::8a) 56 data bytes
64 bytes from 2404:6800:4003:c00::8a: icmp_seq=1 ttl=58 time=2.25 ms
64 bytes from 2404:6800:4003:c00::8a: icmp_seq=2 ttl=58 time=2.12 ms
^C
显示我的单声道版本
# mono --version
Mono JIT compiler version 4.2.3 (Stable 4.2.3.4/832de4b Wed Mar 16 13:19:08 UTC 2016)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
TLS: __thread
SIGSEGV: altstack
Notifications: epoll
Architecture: amd64
Disabled: none
Misc: softdebug
LLVM: supported, not enabled.
GC: sgen
# mcs --version
Mono C# compiler version 4.2.3.0
编译并运行上面的示例
# mcs dns.cs
# mono dns.exe
DNS.GetHostAddresses: google.com
DNS.NumAddreses:6
addr: 74.125.200.102 family: InterNetwork
addr: 74.125.200.139 family: InterNetwork
addr: 74.125.200.138 family: InterNetwork
addr: 74.125.200.101 family: InterNetwork
addr: 74.125.200.113 family: InterNetwork
addr: 74.125.200.100 family: InterNetwork
DNS.GetHostEntry NumAddresses:6
addr: 74.125.200.100 family: InterNetwork
addr: 74.125.200.113 family: InterNetwork
addr: 74.125.200.139 family: InterNetwork
addr: 74.125.200.102 family: InterNetwork
addr: 74.125.200.138 family: InterNetwork
addr: 74.125.200.101 family: InterNetwork
一些答案/评论建议.NET在仅ipv4机器上过滤掉ipv6。这显然不是仅限ipv4的机器。
注意：这是在同一台机器上的node.js中做同样的事情。它正确获取ipv6地址以及ipv4地址
# node
> require('dns').lookup("google.com", {all:true}, (err, addresses) => { console.log(addresses); });
GetAddrInfoReqWrap {
callback: { [Function: asyncCallback] immediately: true },
family: 0,
hostname: 'google.com',
oncomplete: [Function: onlookupall],
domain:
Domain {
domain: null,
_events: { error: [Function] },
_eventsCount: 1,
_maxListeners: undefined,
members: [] } }
> [ { address: '74.125.200.101', family: 4 },
{ address: '74.125.200.138', family: 4 },
{ address: '74.125.200.102', family: 4 },
{ address: '74.125.200.139', family: 4 },
{ address: '74.125.200.113', family: 4 },
{ address: '74.125.200.100', family: 4 },
{ address: '2404:6800:4003:c00::65', family: 6 } ]
如何让DNS.GetHostAddresses或DNS.GetHostEntry返回ipv6和ipv4地址？
答案
这是从MSDN站点（https://msdn.microsoft.com/en-us/library/system.net.ipaddress(v=vs.110).aspx）获取的，它显示了如何在地址上找到所有相关信息，希望这可能会有所帮助：
// This program shows how to use the IPAddress class to obtain a server
// IP addressess and related information.
using System;
using System.Net;
using System.Net.Sockets;
using System.Text.RegularExpressions;
namespace Mssc.Services.ConnectionManagement
{
class TestIPAddress
{
/**
* The IPAddresses method obtains the selected server IP address information.
* It then displays the type of address family supported by the server and its
* IP address in standard and byte format.
**/
private static void IPAddresses(string server)
{
try
{
System.Text.ASCIIEncoding ASCII = new System.Text.ASCIIEncoding();
// Get server related information.
IPHostEntry heserver = Dns.GetHostEntry(server);
// Loop on the AddressList
foreach (IPAddress curAdd in heserver.AddressList)
{
// Display the type of address family supported by the server. If the
// server is IPv6-enabled this value is: InternNetworkV6. If the server
// is also IPv4-enabled there will be an additional value of InterNetwork.
Console.WriteLine("AddressFamily: " + curAdd.AddressFamily.ToString());
// Display the ScopeId property in case of IPV6 addresses.
if(curAdd.AddressFamily.ToString() == ProtocolFamily.InterNetworkV6.ToString())
Console.WriteLine("Scope Id: " + curAdd.ScopeId.ToString());
// Display the server IP address in the standard format. In
// IPv4 the format will be dotted-quad notation, in IPv6 it will be
// in in colon-hexadecimal notation.
Console.WriteLine("Address: " + curAdd.ToString());
// Display the server IP address in byte format.
Console.Write("AddressBytes: ");
Byte[] bytes = curAdd.GetAddressBytes();
for (int i = 0; i < bytes.Length; i++)
{
Console.Write(bytes[i]);
}
Console.WriteLine("
");
}
}
catch (Exception e)
{
Console.WriteLine("[DoResolve] Exception: " + e.ToString());
}
}
// This IPAddressAdditionalInfo displays additional server address information.
private static void IPAddressAdditionalInfo()
{
try
{
// Display the flags that show if the server supports IPv4 or IPv6
// address schemas.
Console.WriteLine("
SupportsIPv4: " + Socket.SupportsIPv4);
Console.WriteLine("SupportsIPv6: " + Socket.SupportsIPv6);
if (Socket.SupportsIPv6)
{
// Display the server Any address. This IP address indicates that the server
// should listen for client activity on all network interfaces.
Console.WriteLine("
IPv6Any: " + IPAddress.IPv6Any.ToString());
// Display the server loopback address.
Console.WriteLine("IPv6Loopback: " + IPAddress.IPv6Loopback.ToString());
// Used during autoconfiguration first phase.
Console.WriteLine("IPv6None: " + IPAddress.IPv6None.ToString());
Console.WriteLine("IsLoopback(IPv6Loopback): " + IPAddress.IsLoopback(IPAddress.IPv6Loopback));
}
Console.WriteLine("IsLoopback(Loopback): " + IPAddress.IsLoopback(IPAddress.Loopback));
}
catch (Exception e)
{
Console.WriteLine("[IPAddresses] Exception: " + e.ToString());
}
}
public static void Main(string[] args)
{
string server = null;
// Define a regular expression to parse user's input.
// This is a security check. It allows only
// alphanumeric input string between 2 to 40 character long.
Regex rex = new Regex(@"^[a-zA-Z]w{1,39}$");
if (args.Length < 1)
{
// If no server name is passed as an argument to this program, use the current
// server name as default.
server = Dns.GetHostName();
Console.WriteLine("Using current host: " + server);
}
else
{
server = args[0];
if (!(rex.Match(server)).Success)
{
Console.WriteLine("Input string format not allowed.");
return;
}
}
// Get the list of the addresses associated with the requested server.
IPAddresses(server);
// Get additonal address information.
IPAddressAdditionalInfo();
}
}
}
编辑
对我的Win 10机器的研究表明，IPv6地址仅返回给本地主机，而不是具有GetHostEntry或GetHostAddresses的互联网主机。会更进一步。
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