iptables

Aleksandar Milivojevic alex at milivojevic.org
Wed Dec 13 23:04:06 UTC 2006


Quoting tamer amr <tamer_linux at yahoo.com>:

>   i want to know what is the  --syn  option doing in the iptables rule ?

As manual page says, it will match packets with the SYN bit set, and  
the ACK and RST bits cleared.

>  because i want to know what is the SYN,ACK   packets ?

SYN,ACK is usually second packet exchanged when establishing TCP  
connection (the response to initial SYN packet).  For details on how  
TCP works, I'd suggest some good book, such as TCP/IP Illustrated by  
W. Richard Stevens (available from Amazon, among other places).  You'd  
probably want to read volume 1.  Volumes 2 and 3 are also interesting  
read.





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