Class NetHelper

Useful network related utilities.

Inheritance

object

NetHelper

Namespace: Neon.Net

Assembly: Neon.Common.dll

Syntax

public static class NetHelper

Methods

AddressEquals(IPAddress, IPAddress)

Determines whether two IP addresses are equal.

Declaration

public static bool AddressEquals(IPAddress address1, IPAddress address2)

Parameters

Type	Name	Description
IPAddress	address1	Address 1.
IPAddress	address2	Address 2.

Returns

Type	Description
bool	true if the addresses are equal.

AddressIncrement(IPAddress, int)

Increments an IPv4 address by adding an integer value.

Declaration

public static IPAddress AddressIncrement(IPAddress address, int incrementBy = 1)

Parameters

Type	Name	Description
IPAddress	address	The input IPv4 address.
int	incrementBy	The increment value (defaults to +1).

Returns

Type	Description
IPAddress	The next address or 0.0.0.0 when we wrap-around the address space.

Exceptions

Type	Condition
NotSupportedException	Thrown for non-IPv4 addresses.

AddressToUint(IPAddress)

Converts an IPv4 address into a 32-bit unsigned integer equivalent.

Declaration

public static uint AddressToUint(IPAddress address)

Parameters

Type	Name	Description
IPAddress	address	The input IPv4 address.

Returns

Type	Description
uint	The 32-bit unsigned integer equivalent.

ComputeMSS(int, bool)

Computes the TCP maximum segment size for a given MTU, optionally taking a VXLAN wrapper headers into account.

Declaration

public static int ComputeMSS(int mtu = 1500, bool vxLan = false)

Parameters

Type	Name	Description
int	mtu	Specifies the target MTU (defaults to DefaultMTU).
bool	vxLan	Optionally indicates that traffic is routed via a VXLAN.

Returns

Type	Description
int	The maximum segment size in bytes.

DeleteArpEntry(IPAddress)

Removes the cached ARP entry for an IP address if it's present.

note

This is currently supported only for Windows.

Declaration

public static void DeleteArpEntry(IPAddress address)

Parameters

Type	Name	Description
IPAddress	address	Specifies the IP address being removed from the ARP cache.

Exceptions

Type	Condition
NotSupportedException	Thrown when the current platform is not supported.

EnsureSuccess(HttpStatusCode, string)

Ensures that the status code passed indicates an HTTP request completed successfully.

note

Status codes between 200-299 are considered to indicate success.

Declaration

public static HttpStatusCode EnsureSuccess(HttpStatusCode statusCode, string reasonPhrase = null)

Parameters

Type	Name	Description
HttpStatusCode	statusCode	Specifies the status code.
string	reasonPhrase	Optionally specifies the reason phrase to be included in any exception thrown.

Returns

Type	Description
HttpStatusCode	The status code passed.

Exceptions

Type	Condition
HttpException	Thrown for non-success status codes.

GetAddressUriHost(IPAddress)

Converts an IPAddress into a host name suitable for using as a Uri host name. For IPv4 addresses, this just returns the address as a string. For IPv6 address, this returns the address surrounded by "[...]" to make it compatible with URI standards.

Declaration

public static string GetAddressUriHost(IPAddress address)

Parameters

Type	Name	Description
IPAddress	address	The IP address.

Returns

Type	Description
string	The host name suitable for including in a URI.

Exceptions

Type	Condition
NotSupportedException	Thrown for non IPv4 or IPv6 addresses.

GetArpFlatTableAsync()

Returns a flattened ARP table for the current machine. This is just a dictionary keyed by IP addresses mapping to the cached MAC address.

note

This is currently supported only for Windows.

Declaration

public static Task<Dictionary<IPAddress, byte[]>> GetArpFlatTableAsync()

Returns

Type	Description
Task<Dictionary<IPAddress, byte[]>>	The IP/MAC dictionary.

Exceptions

Type	Condition
NotSupportedException	Thrown when the current platform is not supported.

GetArpTableAsync()

Returns the ARP table for the current machine.

note

This is currently supported only for Windows.

Declaration

public static Task<Dictionary<IPAddress, Dictionary<IPAddress, byte[]>>> GetArpTableAsync()

Returns

Type	Description
Task<Dictionary<IPAddress, Dictionary<IPAddress, byte[]>>>	A dictionary of dictionaries, with the first level keyed by network interface IP address, returning a dictionary relating IP addresses to MAC addresses for that interface.

Exceptions

Type	Condition
NotSupportedException	Thrown when the current platform is not supported.

GetConnectedGatewayAddress()

Returns an upstream getway address for the network interface returned by GetConnectedInterface().

Declaration

public static IPAddress GetConnectedGatewayAddress()

Returns

Type	Description
IPAddress	The IP address or null if there doesn't appear to be a connected network interface.

Remarks

This works via a somewhat fragile heuristic. We list all network interfaces, filter out those that are loopback, TAP interfaces, Hyper-V switches as well as any that aren't up and then return the highest speed interface from any remaining interfaces.

This may not work as expected for machines with multiple active connections to different networks.

GetConnectedInterface()

Returns a connected network interface with an IPv4 address.

Declaration

public static NetworkInterface GetConnectedInterface()

Returns

Type	Description
NetworkInterface	The connected interface or null if there doesn't appear to be a connected network interface.

Remarks

This works via a somewhat fragile heuristic. We list all network interfaces, filter out those that are loopback, TAP interfaces, Hyper-V switches as well as any that aren't up and then return the highest speed interface from any remaining interfaces.

This may not work as expected for machines with multiple active connections to different networks.

GetMacAddressAsync(IPAddress)

Attempts to fetch the MAC address associated with an IP address.

note

This is currently supported only for Windows.

Declaration

public static Task<byte[]> GetMacAddressAsync(IPAddress address)

Parameters

Type	Name	Description
IPAddress	address	Specifies the IP address.

Returns

Type	Description
Task<byte[]>	The MAC address as a byte array or null when no MAC address could be located.

Remarks

This works by sending an ICMP ping to address and then using the arp command line tool to fetch the local ARP table in an attempt to locate the MAC address. The idea here is that the ping should cause the target's MAC address to be added to the ARP table when the target is running and is on the local network.

note

The first MAC address for the IP address found will be returned.

Exceptions

Type	Condition
NotSupportedException	Thrown when the current platform is not supported.

GetNetworkConfiguration()

Returns basic information about the current network connection including the machine's routable IP address, the network CIDR and gateway as well as the DNS server addresses.

Declaration

public static NetworkConfiguration GetNetworkConfiguration()

Returns

Type	Description
NetworkConfiguration	A NetworkConfiguration with the information or null when the computer doesn't appear to be connected to a network.

Remarks

This implementation is somewhat fragile because it relies on GetRoutableIpAddress() which uses heuristics to try to identify a suitable connected network. This may not work as expected for machines with multiple active connections to different networks.

GetReachableHost(IEnumerable<string>, ReachableHostMode)

Pings one or more hostnames or IP addresses in parallel to identify one that appears to be online and reachable via the network (because it answers a ping).

Declaration

public static ReachableHost GetReachableHost(IEnumerable<string> hosts, ReachableHostMode failureMode = ReachableHostMode.ReturnFirst)

Parameters

Type	Name	Description
IEnumerable<string>	hosts	The hostname or IP addresses to be tested.
ReachableHostMode	failureMode	Specifies what should happen when there are no reachable hosts. This defaults to ReturnFirst.

Returns

Type	Description
ReachableHost	A ReachableHost instance describing the host or null.

Exceptions

Type	Condition
NetworkException	Thrown if no hosts are reachable and failureMode is passed as Throw.

GetReachableHosts(IEnumerable<string>)

Pings one or more hostnames or IP addresses in parallel to identify those that appear to be online and reachable via the network (because it answers a ping).

Declaration

public static IEnumerable<ReachableHost> GetReachableHosts(IEnumerable<string> hosts)

Parameters

Type	Name	Description
IEnumerable<string>	hosts	The hostname or IP addresses to be tested.

Returns

Type	Description
IEnumerable<ReachableHost>	The ReachableHost instances describing the reachable hosts (if any).

GetRoutableIpAddress()

Returns a routable (non-loopback) IPv4 address for the current machine.

note

This returns a routable IP address from the network interface returned by GetConnectedInterface() when there is a connected interface.

Declaration

public static IPAddress GetRoutableIpAddress()

Returns

Type	Description
IPAddress	The IP address or null if there doesn't appear to be a connected network interface.

Remarks

This works via a somewhat fragile heuristic. We list all network interfaces, filter out those that are loopback, TAP interfaces, Hyper-V switches as well as any that aren't up and then return the highest speed interface from any remaining interfaces.

This may not work as expected for machines with multiple active connections to different networks.

GetUnusedTcpPort(int, int, IPAddress)

Returns a free TCP port for a local network interface within a given range of ports.

Declaration

public static int GetUnusedTcpPort(int startPort, int endPort, IPAddress address = null)

Parameters

Type	Name	Description
int	startPort	The first port to check
int	endPort	The last port to check.
IPAddress	address	Optionally specifies the target interface's IP address. This defaults to Any where an unused port will be returned that is available on all network interfaces.

Returns

Type	Description
int	The free port number.

Remarks

note

The behavior when GetUnusedTcpPort(IPAddress) is called multiple times without actually listening on the ports is somewhat undefined.

We believe most operating systems won't return the same port again for a while (perhaps a few minutes) so you're probably safe retrieving a few unused ports before using them for testing and other non-production purposes.

Production code should begin listening on and unused ports immediately after retrieving one. This will ensure that the unused ports returned will be unique and also help avoid having another application grab the port before you have a chance to listen on it.

Exceptions

Type	Condition
NetworkException	Thrown when there are no available ports.

GetUnusedTcpPort(IPAddress)

Returns a free TCP port for a local network interface.

Declaration

public static int GetUnusedTcpPort(IPAddress address = null)

Parameters

Type	Name	Description
IPAddress	address	Optionally specifies the target interface's IP address. This defaults to Any where an unused port will be returned that is available on all network interfaces.

Returns

Type	Description
int	The free port number.

Remarks

note

The behavior when GetUnusedTcpPort(IPAddress) is called multiple times without actually listening on the ports is somewhat undefined.

We believe most operating systems won't return the same port again for a while (perhaps a few minutes) so you're probably safe retrieving a few unused ports before using them for testing and other non-production purposes.

Production code should begin listening on and unused ports immediately after retrieving one. This will ensure that the unused ports returned will be unique and also help avoid having another application grab the port before you have a chance to listen on it.

Exceptions

Type	Condition
NetworkException	Thrown when there are no available ports.

IsValidDnsHost(string)

Verifies that a string is a valid DNS hostname.

Declaration

public static bool IsValidDnsHost(string host)

Parameters

Type	Name	Description
string	host	The hostname being tested.

Returns

Type	Description
bool	true if the hostname is valid.

IsValidDnsLabel(string)

Verifies that a string is a valid DNS label.

Declaration

public static bool IsValidDnsLabel(string label)

Parameters

Type	Name	Description
string	label	The label being tested.

Returns

Type	Description
bool

IsValidPort(int)

Determines whether an integer is a valid network port number.

Declaration

public static bool IsValidPort(int port)

Parameters

Type	Name	Description
int	port	The port.

Returns

Type	Description
bool	true if the port is valid.

ListLocalHostsSections()

Lists the names of the local host sections.

Declaration

public static IEnumerable<LocalHostSection> ListLocalHostsSections()

Returns

Type	Description
IEnumerable<LocalHostSection>	The section names converted to uppercase.

ModifyLocalHosts(string, Dictionary<string, IPAddress>)

Used to modify the $/etc/hosts file used by the DNS resolver for testing, debugging and possibly other purposes.

note

WARNING: Modifying the hosts file will impact all processes on the system, not just the current process.

Declaration

public static void ModifyLocalHosts(string section, Dictionary<string, IPAddress> hostEntries = null)

Parameters

Type	Name	Description
string	section	Specifies the string to use to delimit the host names section. This is required and must be a non-empty string consisting of up to 63 non-control ASCII characters. Section names are case sensitive.
Dictionary<string, IPAddress>	hostEntries	A dictionary mapping the hostnames to an IP address or null.

Remarks

note

This method requires elevated administrative privileges.

This method adds or removes a temporary section of host entry definitions delimited by special comment lines. When hostEntries is non-null and non-empty, the section will be added or updated. Otherwise, the section will be removed.

You can remove all host sections by passing both hostEntries and section as null.

ParseIPv4Address(string)

Parses an IPv4 address.

Declaration

public static IPAddress ParseIPv4Address(string input)

Parameters

Type	Name	Description
string	input	The address text.

Returns

Type	Description
IPAddress	The IPAddress.

Exceptions

Type	Condition
FormatException	Thrown for an invalid address.

ParseIPv4Endpoint(string)

Parses an IPv4 endpoint from a string.

Declaration

public static IPEndPoint ParseIPv4Endpoint(string input)

Parameters

Type	Name	Description
string	input	The input.

Returns

Type	Description
IPEndPoint	The parsed IPEndPoint.

Exceptions

Type	Condition
FormatException	Thrown if the input is not valid.

ParseIPv6Address(string)

Parses an IPv6 address.

Declaration

public static IPAddress ParseIPv6Address(string input)

Parameters

Type	Name	Description
string	input	The address text.

Returns

Type	Description
IPAddress	The IPAddress.

Exceptions

Type	Condition
FormatException	Thrown for an invalid address.

TcpPortIsFree(int, IPAddress)

Checks to see whether a TCP port is free on a given IP address.

Declaration

public static bool TcpPortIsFree(int port, IPAddress address = null)

Parameters

Type	Name	Description
int	port	The port number.
IPAddress	address	The optional IP address. If not specified, defaults to Any.

Returns

Type	Description
bool

ToAwsS3Uri(string)

Converts an S3 or standard HTTPS URI into an S3 URI.

Declaration

public static string ToAwsS3Uri(string uri)

Parameters

Type	Name	Description
string	uri	The source URI.

Returns

Type	Description
string	The equivalent S3 URI.

TryParseIPv4Address(string, out IPAddress)

Attempts to parse an IPv4 address.

Declaration

public static bool TryParseIPv4Address(string input, out IPAddress address)

Parameters

Type	Name	Description
string	input	The address text.
IPAddress	address	Set to the parsed address on success.

Returns

Type	Description
bool	true on success.

TryParseIPv4Endpoint(string, out IPEndPoint)

Attempts to parse an IPv4 network endpoint.

Declaration

public static bool TryParseIPv4Endpoint(string input, out IPEndPoint endpoint)

Parameters

Type	Name	Description
string	input	The input string.
IPEndPoint	endpoint	Returns as the parsed endpoint.

Returns

Type	Description
bool	true on success.

TryParseIPv6Address(string, out IPAddress)

Attempts to parse an IPv4 address.

Declaration

public static bool TryParseIPv6Address(string input, out IPAddress address)

Parameters

Type	Name	Description
string	input	The address text.
IPAddress	address	Set to the parsed address on success.

Returns

Type	Description
bool	true on success.

UintToAddress(uint)

Converts an unsigned 32-bit integer into an IPv4 address.

Declaration

public static IPAddress UintToAddress(uint value)

Parameters

Type	Name	Description
uint	value	The input value.

Returns

Type	Description
IPAddress	The IPAddress.