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Router in C# for demonstrational purposes.

C# 99.80% Dockerfile 0.20%

router arp routing rip lldp sniffing dhcp-server docker csharp

router's Introduction

Router in C#

Made for WANT 2019.

GUI

This is server-only. GUI can be found here.

Features:

ARP (proxy ARP)
C, S Routing
Dynamic Routing using RIP
LLDP
Snniffing packets
DHCP server

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router's Issues

ProxyARP Preload

Fetch ARP on Proxy ARP request and andswer only 100% valid IPs.

C & S

Moze byt rovnaka C siet aj S?
Co ak je C, moze vzniknut S?
Co ak je S, moze vzniknut C?

DHCP Free from Pool

Po vymazani statickej adresy sa vymaze z poolu, ak tam nahodou je.

RTEs to byte[]

            int newSize = 4 + (value.Count * 20);
            if(newSize != Data.Length)
            {
                Array.Resize(ref Data, 4 + (value.Count * 20));
            }

            var ms = new MemoryStream();
            foreach (RTE item in value)
            {
                var itemBytes = item.Bytes;
                ms.Write(itemBytes, 0, itemBytes.Length);
            }

            var Dst = ms.ToArray();
            Array.Copy(Data, 4, Dst, 0, Dst.Length);

Payload Packet

Append payload to any packets.

Extend existing GeneratorPacket class to payload. Existing payload cases can overrite default method. => Get rid of Generator Payload.

JSON Converter - Error Handling

Thrown Exceptions from converters are not being catched.

DHCP

https://www.ietf.org/rfc/rfc2132.txt
http://www.tcpipguide.com/free/t_DHCPMessageFormat.htm

Ked sa prijme siet s metrikou 16 a uz sa nachadza v RIP Tabulke nejaka siet, prepne sa do stavu Holddown. Avsak ked ten stav vyprsi, tak potom zostane ta povodna siet v tabulke aktivna? Alebo sa stane rovno inactive?

C Routes must have unique Network.

Dva interfaces nemozu mat rovnaku siet. Treba overovat pri ulozeni.

Split horizon

Neposielat pakety na rozhranie z ktoreho prislo.

RIP: Out of range when no Routes

On an RIP Packet arrival, Packet.cs went out of index.

        protected byte[] Slice(int o, int len)
        {
            var Value = new Byte[len];
            for (var i = 0; i < len && i < Length; i++)
            {
                Value[i] = RawData[o + i];
            }

            return Value;
        }

   at Router.Helpers.Packet.Slice(Int32 o, Int32 len) in C:\Users\m1k1o\source\repos\Router\Router\Helpers\Packet.cs:line 119
   at Router.Protocols.RIPPacket.get_RouteCollection() in C:\Users\m1k1o\source\repos\Router\Router\Protocols\RIPPacket.cs:line 32
   at Router.RIP.RIPService.OnPacketArrival(Handler Handler) in C:\Users\m1k1o\source\repos\Router\Router\RIP\RIPService.cs:line 98
   at Router.PacketArrival.Invoke(Handler Handler)
   at Router.Interface.<.ctor>b__28_0(RawCapture Packet) in C:\Users\m1k1o\source\repos\Router\Router\Interface.cs:line 30
   at Router.Helpers.Device.<Start>b__26_0(Object sender, CaptureEventArgs e) in C:\Users\m1k1o\source\repos\Router\Router\Helpers\Device.cs:line 94
   at SharpPcap.LibPcap.PcapDevice.SendPacketArrivalEvent(RawCapture p)
   at SharpPcap.WinPcap.WinPcapDevice.SendPacketArrivalEvent(RawCapture p)
   at SharpPcap.LibPcap.PcapDevice.PacketHandler(IntPtr param, IntPtr header, IntPtr data)
   at SharpPcap.LibPcap.LibPcapSafeNativeMethods.pcap_dispatch(IntPtr adaptHandle, Int32 count, pcap_handler callback, IntPtr ptr)
   at SharpPcap.LibPcap.PcapDevice.CaptureThread()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

RIP Respoonse: Packet

Max 25 sieti, ak viac, poslat viacero updates.

WS Sniffing for each Connection

Sniffinng packets should be independent for each vonnection. But I could not unsubscribe event.

RIP Triggered update: Imlementation

1 Používať Changed Flag podľa implementácie.
2 Počkať 1 - 5 sec pred odoslaním.

Sync / Async ?

Samotný routing by mal byť synchrónny - v akom poradí sa prijmú paktety v takom poradí sa odošlú.

ARP musí byť asynchrónny - ak čaká paket na spracovanie, pošle ARP request, nikdy by ho nedočkal lebo sám blokuje príjmanie.

RIP môže / nemusí byť asynchrónny.

RIP Flush timer

Po expirovani Flush Timeru treba ihned vymazat, nie pasivne.

DHCP auto END

Auto add END at the end of collection if not present.

Zmena IP a Masky počas behu

IP a Maska sa dá meniť počas behu. Tieto zmeny sa musia odraziť aj v Routing a RIP tabuľke.

Spraviť mutovať IP a Network je časť riešenia, pre RT je to v pohode, avšak pri RIP môžu nastať konflikty, ak by sa už nachádzala taká sieť v tabuľke od toho interface-u.

RIP Routa po prijati metriky 16

Keď smerovač prijme cestu s metrikou 16, odstráni ju zo smerovacej tabuľky, ale zostáva v databáze ako possibly down, pošle triggered update o tejto sieti s metrikou 16.

ICMP bad checksum

Data:

0000   08 00 4b bd 00 9b 03 bb 54 45 53 54 53 K½»TESTS

Tree:

Internet Control Message Protocol
    Type: 8 (Echo (ping) request)
    Code: 0
    Checksum: 0x4bbd incorrect, should be 0xf90f
        [Expert Info (Warning/Checksum): Bad checksum [should be 0xf90f]]
            [Bad checksum [should be 0xf90f]]
            [Severity level: Warning]
            [Group: Checksum]
    [Checksum Status: Bad]
    Identifier (BE): 155 (0x009b)
    Identifier (LE): 39680 (0x9b00)
    Sequence number (BE): 955 (0x03bb)
    Sequence number (LE): 47875 (0xbb03)
    Data (5 bytes)
        Data: 5445535453
        [Length: 5]