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Re: [vox-tech] ssh login slow with iptables
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Re: [vox-tech] ssh login slow with iptables

Brilliant solution!  Thanks!

Samuel Merritt wrote:
Jack LaPlante said:

I'm setting up my nifty new dedicated web server with a firewall
like this: (I'm on RH9, the rpms look like the latest avail )

iptables -F
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -m multiport -p tcp --dport www,ssh,sftp,smtp,10000 \
iptables -A INPUT -j LOG -m limit
iptables -A INPUT -j REJECT

(an o'reilly setup from the linux security cookbook)

Now, when I log in via SSH or SFTP, there is a 30 second pause while my
password authorizes.  It used to take a second or two.  Flush the rules
and the login is up to speed again.

You don't allow inbound 53/udp, so your machine can't use DNS. By default,
sshd looks up the name of the connecting machine, and it looks like the
DNS lookup takes 30 seconds to time out.

I want to force my clients to use SFTP for all their file transfers but
the delay is going to be annoying.

Any suggestions to speed up my logins?

iptables -A INPUT --source $DNS_SERVER_IP_HERE -p udp --sport 53 -j ACCEPT

Assuming I got the syntax right, do that once for each DNS server you have.



 Jack LaPlante

 Pyroglyph Inc.

        Clarity and Style
        For the Digital Age
  pyroglyph.com  pwx.com  uneasychair.com
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