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Old 07-31-2007, 12:49 AM   #1
raklo
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TCP/IP protocol stack query ??????


hi all,
i m confusd bout certain fields of IP header cud u solve them

1)wot wd be the fate of packet if TTL=0 ??

2)wot wd be the fate of packet if TTL=1 ??

3)If my packet is not fragmented,then is there any
use of Identification field in the IP header???

4) If i wanna add my own custom byte into the ip header
,wotz the least laborious way to do it???

regards
 
Old 07-31-2007, 01:04 AM   #2
acid_kewpie
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1) it'd be timed out as ttl expired

2) TTL is decremented to 0 as it moves to the next hop, then as 1).

3) no

4) edit the tcpip stack code on all affected systems i guess.
 
Old 07-31-2007, 01:13 AM   #3
raklo
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thanx a lot,for this upto the mark reply.
for the ans 2) that u gave.
does the TTL decrement at the sender level,or at the receipent level.i.e,is it
decremented and sent,or sent and then at the other side decremented????

for the ans 3) that u gave,
if my packet is not fragmented,if i fill identification field with random bits
then wud that make a difference???


for the ans 4) ,
do u think raw sockets will help me in anyway for my purpose???n also
at which layer r the sockets formed??

regards
 
Old 07-31-2007, 04:27 AM   #4
raklo
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also cd anyone tell me at which layer is TTL checked????
 
Old 07-31-2007, 07:09 AM   #5
acid_kewpie
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well for 2 i assume the ttl is decremented as it is sent on to the next hop, as if it were addressed for itself it wouldn't decrement.

for 3 and 4 i have no idea... read the tcp/ip standards and ttl is an IP attribute, so would be checked at the layer equivalent to IP. i'm sure you can find which one that is yourself.
 
  


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