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sims
sims
Explorer II
March 27, 2019
Solved

NAT BASIC

  • March 27, 2019
  • 1 reply
  • 3329 views
Hi , I have the following Nat enabled policy Incoming interface is 10.1.1.1/24 Outgoing interface ip 4.4.4.4/24 And route  to  destination 8.8.8.8  via  gateway 10.1.1.1   If I ping 8.8.8.8 from source 10.2.2.2/24 . What will be the source ip? What if I ping 10.1.1.1 , the host 8.8.8.8 will reply? Thanks
    Best answer by Toshi_Esumi

    NAT works only for through traffic that would match the policy. Pining the interface coming from the same interface wouldn't hit the policy. It's called "local-in" traffic. The source wouldn't change in the reply packets.

    1 reply

    Toshi_Esumi
    SuperUser
    Toshi_Esumi
    SuperUser
    March 27, 2019

    If your default route (unless you have more specific route for 8.8.8.8) is pointing toward the outgoing interface, it would be SNATed with 4.4.4.4. That's what 8.8.8.8 side sees in the ping packet source IP, then where it would reply to.

    If you run sniffer like "diag sniffer packet any 'host 8.8.8.8' 4", you would see those address changes at the NAT.

    sims
    simsAuthor
    Explorer II
    April 1, 2019

    Hi,

    What if i ping the incoming interface , there will be any translation 

    Thanks  

    Toshi_Esumi
    SuperUser
    Toshi_EsumiAnswer
    SuperUser
    April 1, 2019

    NAT works only for through traffic that would match the policy. Pining the interface coming from the same interface wouldn't hit the policy. It's called "local-in" traffic. The source wouldn't change in the reply packets.

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