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Date:      Tue, 29 May 2001 16:31:33 -0500
From:      Ryan <ryanpek@swbell.net>
To:        freebsd-security@freebsd.org
Subject:   Re: Syn+Fin (Setup) And TCP RST
Message-ID:  <002001c0e886$c440b2d0$45d8db40@mhx800>
References:  <010f01c0e888$5ab3c120$b88f39d5@a>
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[-- Attachment #1 --]
once again.. use ssh2
its alot safer!

  ----- Original Message ----- 
  From: Liran Dahan 
  To: freebsd-security@freebsd.org 
  Sent: Tuesday, May 29, 2001 4:43 PM
  Subject: Syn+Fin (Setup) And TCP RST


  I've added those 2 options in my kernel long time ago:
  options         TCP_DROP_SYNFIN         #drop TCP packets with SYN+FIN
  options         TCP_RESTRICT_RST        #restrict emission of TCP RST          


  Is this could be the reason why even when i add in my firewall to send RST packets, it takes me 30 seconds till i get timeout of Connection refused when i telneting my box on randomly closed ports.. ? 

  And about TCP_DROP_SYNFIN .. is this could be one of the reasons 'setup' command 'aint working on my ipfw?

  If my speculations are true... Why those kernel options are used for?

  Thanks,

            Liran Dahan (lirandb@netvision.net.il)

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<DIV><FONT size=2>once again.. use ssh2</FONT></DIV>
<DIV><FONT size=2>its alot safer!</FONT></DIV>
<DIV>&nbsp;</DIV>
<BLOCKQUOTE dir=ltr 
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
  <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV 
  style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B> 
  <A title=lirandb@netvision.net.il href="mailto:lirandb@netvision.net.il">Liran 
  Dahan</A> </DIV>
  <DIV style="FONT: 10pt arial"><B>To:</B> <A title=freebsd-security@freebsd.org 
  href="mailto:freebsd-security@freebsd.org">freebsd-security@freebsd.org</A> 
  </DIV>
  <DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, May 29, 2001 4:43 PM</DIV>
  <DIV style="FONT: 10pt arial"><B>Subject:</B> Syn+Fin (Setup) And TCP 
RST</DIV>
  <DIV><BR></DIV>
  <DIV><FONT face=Arial size=2>
  <DIV><FONT face=Arial size=2>I've added those 2 options in my kernel long time 
  ago:</FONT></DIV>
  <DIV><FONT face=Arial 
  size=2>options&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  TCP_DROP_SYNFIN&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; #drop TCP 
  packets with 
  SYN+FIN<BR>options&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
  TCP_RESTRICT_RST&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; #restrict emission 
  of TCP RST&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>Is this could be the reason why even when i add 
  in my firewall to send RST packets, it takes me 30 seconds till i get timeout 
  of Connection refused when i telneting my box on randomly closed ports.. ? 
  </FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>And about TCP_DROP_SYNFIN .. is this could be one 
  of the reasons 'setup' command 'aint working on my ipfw?</FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>If my speculations are true... Why those kernel 
  options are used for?</FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>Thanks,</FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=Arial 
  size=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Liran Dahan (<A 
  href="mailto:lirandb@netvision.net.il">lirandb@netvision.net.il</A>)</FONT></DIV></FONT></DIV></BLOCKQUOTE></BODY></HTML>

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