C#/.NET/LINQ: DotNetStat: netstat.exe with TCP ports grouped by host
Posted by jpluimers on 2013/06/18
A lot of people have written .NET equivalents of netstat code. Basically there are two starting points:
- Use the built-in System.Net.NetworkInformation.IPGlobalProperties.GetIPGlobalProperties method, for instance by
– Build your own netstat.exe with c# | Tim Van Wassenhove.
– Netstat in C# « Towards Next. - A P/Invoke wrapper around the Windows IP Helper function GetExtendedTcpTable, which adds process information, for instance by
– windows – Which PID listens on a given port in c# – Stack Overflow.
– Netstat Example – CodeProject.
I adapted the first, made the output very much like the built-in Windows netstat, and added some LINQ code to demonstrate grouping and ordering.
Now you get grouped output like this:
Distinct Remote Address:Port pairs by Remote Address: 107.20.249.140 443 107.20.249.78 443 127.0.0.1 6421, 19872 192.168.1.81 17500, 61678 199.47.218.159 443 199.47.219.148 80 199.47.219.160 443 23.21.220.140 443 23.23.127.94 443
The code below is part of the DotNetStat example.
It demonstrates a few important LINQ aspects beyond the LINQ Query Expressions (C# Programming Guide) intro and 101 LINQ Samples in C#.:
- LINQ translates C# query keywords into framework members, for instance into extension methods in Enumerable Methods (System.Linq).
- LINQ uses delayed execution, so a lot of errors will not only absent during compile time, nor at LINQ query setup, but delayed until the portions of the query are being executed.
- In this case, it means that if you get the orderby wrong, you will get the an error like At least one object must implement IComparable inside the foreach loop.
- There is no distinct keyword, so you have to use one of the overloads of the Enumerable.Distinct Method (System.Linq).
- The group member by sub-member does not require an IComparable
When you really want to dig deeply into LINQ, then Reimplementing LINQ to Objects: Part 45 – Conclusion and List of Posts – Jon Skeet: Coding Blog and LINQ – Jon Skeet: Coding Blog are.recommended reading.
Now a short table of C# query keywords and members in the framework:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.NetworkInformation;
namespace DotNetStat
{
class Program
{
static void Main()
{
IPGlobalProperties ipProperties = IPGlobalProperties.GetIPGlobalProperties();
TcpConnectionInformation[] tcpConnections = ipProperties.GetActiveTcpConnections();
if (tcpConnections.Length != 0)
{
Console.WriteLine("Distinct Remote Address:Port pairs by Remote Address:");
IEnumerable<IGrouping<IPAddress, TcpConnectionInformation>> tcpConnectionsByRemoteaddressGroups =
from tcpConnection in tcpConnections
//orderby tcpConnection.RemoteEndPoint.Address // "At least one object must implement IComparable." because Address has no IComparable
orderby tcpConnection.RemoteEndPoint.Address.ToString()
group tcpConnection by tcpConnection.RemoteEndPoint.Address;
foreach (IGrouping<IPAddress, TcpConnectionInformation> tcpConnectionsByRemoteaddressGroup in tcpConnectionsByRemoteaddressGroups)
{
Console.Write("{0,-15} ", tcpConnectionsByRemoteaddressGroup.Key);
IEnumerable allRemotePorts =
from tcpConnectionsByRemoteaddress in tcpConnectionsByRemoteaddressGroup
orderby tcpConnectionsByRemoteaddress.RemoteEndPoint.Port
select tcpConnectionsByRemoteaddress.RemoteEndPoint.Port;
IEnumerable distinctRemotePorts = allRemotePorts.Distinct();
bool first = true;
foreach (int distinctRemotePort in distinctRemotePorts)
{
if (!first)
Console.Write(", ");
Console.Write(distinctRemotePort);
first = false;
}
Console.WriteLine();
}
}
}
}
}
–jeroen
via: Build your own netstat.exe with c# | Tim Van Wassenhove.
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