Zijici IP adresa

[uhlar na fantomas.sk]

Martin Horak <horakm na mail.sce.cz> wrote:
->> pokial viem, na icmp pakety sa reply nesmie posielat:
->> 
->> rfc792:
->> 
->>    The ICMP messages typically report errors in the processing of
->>    datagrams.  To avoid the infinite regress of messages about
->>    messages etc., no ICMP messages are sent about ICMP messages.  Also
->>    ICMP messages are only sent about errors in handling fragment zero
->>    of fragemented datagrams.  (Fragment zero has the fragment offeset
->>    equal zero).

-> Lidi, ctete manualy. Je tam vsechno.

manual k com? Ten k traceroute som cital a zda sa mi ze odporuje RFC

-> traceroute -I <host> pouziva misto UDP ICMP ECHO (jako ping).

yo, lenze ked vyprsi TTL, a na ICMP sa nesmie poslat error message...

Co potom router vrati a preco to nedropne? Preco router nedropne ICMP ECHO
request ked nie je urceny jemu a vyprsal TTL?

-> Nekdy se to hodi, treba u firewallu - UDP vetsinou zahazuji, PING
-> propousteji (nebo alespon odpovidaji). 

heheh ja by som skor povedal ze naopak :) kopa lamerov adminov automaticky
zakazuje ICMP...

-> ICMP ECHO bude tedy asi vyjimka ze zmineneho RFC792.

ICMP echo a ICMP ECHO reply je priamo definovane v RFC792 a to takto:

   Description

      The data received in the echo message must be returned in the echo
      reply message.

-- 
 Matus "fantomas" Uhlar, sysadmin at NEXTRA, Slovakia; IRCNET admin of *.sk
 uhlar na fantomas.sk ; http://www.fantomas.sk/ ; http://www.nextra.sk/
 "To Boot or not to Boot, that's the question." [WD1270 Caviar]

---
Odchozí zpráva obsahuje viry.
Zkontrolováno antivirovým systémem AVG (http://www.grisoft.cz).
Verze: 6.0.230 / Virová báze: 111 - datum vydání: 25.1.2001