[linux] Ako routovat ethernet broadcast?

[Peter Surda]

On Thu, Sep 25, 2003 at 08:34:01AM +0200, Miro Bobovsky wrote:
> lebo on tam ma tiez okrem 10,x aj nejaku 20.1.1.200 adresu a preto sa snazi
> cez ff:ff:ff a arp najst cloveka na druhej strane priamo broadcastom.
Ludia, prosim citajte co pisem. Tie divne pakety na ff:ff:ff:ff:ff:ff NIE SU
ARP, ale normalne IP. Takto napriklad "odpoveda", ked 20.1.1.2 posle (cez LR)
DNS request:

(toto je ten request):
08:39:24.674364 0:80:c8:f6:ca:d2 0:2:44:59:5e:36 0800 88: 20.1.1.2.35194 > 62.173.128.77.53:  16487+ PTR?  nieco.in-addr.arpa. (46) (DF)

(a toto reply)
08:39:38.711032 0:2:44:59:5e:36 ff:ff:ff:ff:ff:ff 0800 299: 62.173.128.77.53 > 20.1.1.2.35194:  16487- 0/13/0 (257) (DF)

Keby to bol len zly routing, tak by poslal:
08:39:40.080231 0:2:44:59:5e:36 ff:ff:ff:ff:ff:ff 0806 60: arp who-has 20.1.1.2 tell 10.1.1.1

Ale on nic takeho neposiela.

(62.173.128.77 je nejaky DNS server niekde).

> Nuz aj take sa da vyriesit napr ze na eth0 nechas okrem 10.1.1. aj 20. tkovu
> IP. na eth1 si das uplne inu siet ..
Nepomoze, sprava sa to presne tak isto. Dal som na vonkajsi interfejs napr.
20.1.1.5, ale ta adresa zostava rovnako nepristupna, jednoducho do userspacu
sa tie pakety nedostanu.

> na duhy komp si das aj inu siet (aby bola lanka) a tiez aj dalsiu IP a to
> 20.1.1.2 a na LR povies cez proxy arp ze danu IP 20.1.1.2 cez proxy arp static
> prehodit na siet xy a patricnou routrovacou tabulkou tlacit dovnutra tej inej
> siete na eth1
len proxy_arp zapnut nema ziaden efekt, a cez arp -s mac adresu
ff:ff:ff:ff:ff:ff mi priradit nedovoli.

> Nuz .. to len tak tipujem ze si sa s providerom proste "nepochopil" a on ti
> nedal "siet" ale dal ti len dve IP na SVOJEJ sieti.
Nie, nedal, parkrat som sa pytal.

> bbo
S pozdravom,

Peter Surda (Shurdeek) <shurdeek na panorama.sth.ac.at>, ICQ 10236103, +436505122023

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