Linux Netfilter discussions
 help / color / mirror / Atom feed
From: Grant Taylor <gtaylor@riverviewtech.net>
To: Mail List - Netfilter <netfilter@vger.kernel.org>
Subject: Re: ssh session are hanging when firewall is restarted
Date: Thu, 25 Aug 2011 01:04:50 -0500	[thread overview]
Message-ID: <4E55E602.6040905@riverviewtech.net> (raw)
In-Reply-To: <CA+f1OFoJ06_94U9EpGr=85TZFyuAAScG7a-E7qzs2GuXFaRy9Q@mail.gmail.com>

On 8/24/2011 08:42, Adishesh M wrote:
> what is the problem with this above rule. we used this rule to drop
> bad tcp packets. when firewall is restarted using "service iptables
> restart", ssh sessions are hanging.

I don't think there is any thing wrong with the rule at all.  I think 
the problem is how you are thinking about the connection.

You are looking for connections that are new to the connection tracking 
sub-system that do not have a SYN flag set.

An already established SSH connection will not need to send a SYN 
packet, but will still appear "new" to the connection tracking 
sub-system after you re-start the firewall.

So, IMHO, this behavior should be expected.

I'd sit down and think about how frequently this ""problem (such as it 
is) happens and if it has enough impact to cause me to want to re-design 
firewall rules to take it in to account.



Grant. . . .

  parent reply	other threads:[~2011-08-25  6:04 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-24 13:42 ssh session are hanging when firewall is restarted Adishesh M
2011-08-25  5:41 ` Adishesh M
2011-08-25  6:04 ` Grant Taylor [this message]
2011-08-25  7:28   ` Tyler J. Wagner
2011-08-25  8:06   ` Jan Engelhardt
2011-08-25 10:15 ` Pandu Poluan
2011-08-25 10:34   ` Adishesh M
2011-08-25 10:51     ` Tyler J. Wagner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4E55E602.6040905@riverviewtech.net \
    --to=gtaylor@riverviewtech.net \
    --cc=netfilter@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox