Skip to content

QueenieCplusplus/ND

Folders and files

NameName
Last commit message
Last commit date

Latest commit

 

History

37 Commits
 
 

Repository files navigation

ND

ARP in IPv6

Network Discover, Router Solicitation (探索) & Advertisement (通告), Link_layer addr, SAAC (Stateless Adress Auto Config)

IPv6 結合了 IPv4 的 ARP 與 ICMP 及 Redirect。除了改良了 IPv4 版本也追加了 ND 新功能,此一功能能夠探測鄰近路由是否可到達。

                            /                                         \
                           /                                           \
                          /                                             \
                         /                                               \
                        /                                                 \
     Host ----- RS (Solicitate) ------------   -------------(Advertisement) RA  Router
                        \                                                 /
                         \                                               /
                          \                                             /
                           \                                           /
                            \                                         /

ND defines how to detect unreacheachability using NUD schematics:

  1. to track NUD.

  2. to solicitate which Neighbor Router is able to redirect datagram.

  3. to check subnet mask (prefix).

  4. DHCPv6 使用 SAAC 無接縫或稱無狀態位址自動組態取代 DHCPv4.

  5. to detect the modified data-link layer addr.

  6. max hop counts is 255. Under this index, path will be considered to be TIMEOUT(往返計時逾時).

  7. (omit)

ND specifies the spec of Host & Router. Including: (RFC 4861)

  • ND, Neighbor Discovery

  • RD, Router Discovery

  • AR, Address Resolution

  • NUD, Neighbor Unreachability Detection

  • DAD, Duplicate Address Detection

  • ICMP Redirection

Weakness of ND see RFC 6583

ND is easier to be attacked by DOS, since its Router can be forged to be Default GW and advertise this forged info to other Routers in same Subnet (same prefix or same network mask).

SND

Secure Neighbor Discovery

to avoid DOS by implementing RA (Router Advertisement) Guard, to filter the orifinal router in Link-state layer via ND header.

ND exposes its weakness due to Fragmentation, so SND rules out that fragment is banned.

Neighbor Cache (table) & Destination Cache (local & remote)

the two table is distinguished by the facto that Neighbor is act role as subnet info to DES.

neighbor cached table shows out

  1. the datagram queue is reached to des or not.

  2. reachable Neghibour.

  3. process called if NUD (unreachable) Event happens.

      ASW1$show ipv6 neighbors
      
      IPv6 Addr      age   Link-Layer Addr     State          Interface
      8個16進制位元組        0800:27dd:edd3      REACH(可達)     v110
                                               STALE(失效)     Fa0/1
                                               INCOMPLETE (不完整)
                                               DELAY (延遲)
                                               PROBE (探測)
    

Releases

No releases published

Packages

No packages published