Linux.com | Advanced SSH security tips and tricks - The Diigo Meta page

• 21 Mar 08
  

  Bryan Short

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• 22 Apr 07
  

  Nacho Montoya

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• 10 Apr 07
  

  John LeMasney

  "Some simple tricks to help you tighten security for your secure shell (SSH) service. "

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• 09 Apr 07
  

  Horacio Degiorgi

  access to the SSH service is blocked for one minute, and the user gets only one login try per minute from that moment on:

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• 03 Apr 07
  

  Charles Nadeau

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• 02 Apr 07
  

  Chris Fontenot

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  Maggie Leber

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  Asteris Masouras

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  liu yong

  
  
  
  ~# iptables -A INPUT -p tcp -m state --syn --state NEW --dport 22 -m limit --limit 1/minute --limit-burst 1 -j ACCEPT~# iptables -A INPUT -p tcp -m state --syn --state NEW --dport 22 -j DROPIn a second example, iptables are set to allow only host 19

• 01 Apr 07
  

  FirstN@me L@stN@me

  Advanced SSH security tips and tricks -- article related to Security, System Administration, and Networking.
  

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• 31 Mar 07
  

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• 30 Mar 07
  

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  • SSH time-lock tricks

     

    You can also use different iptables parameters to limit connections to the  SSH service for specific time periods. You can use the /second, /minute, /hour,  or /day switch in any of the following examples.

     

    In the first example, if a user enters the wrong password, access to the SSH  service is blocked for one minute, and the user gets only one login try per  minute from that moment on:

     

    ~# iptables -A INPUT -p tcp -m state --syn --state NEW --dport 22 -m  limit --limit 1/minute --limit-burst 1 -j ACCEPT
~# iptables -A INPUT -p tcp  -m state --syn --state NEW --dport 22 -j DROP

     

    In a second example, iptables are set to allow only host 193.180.177.13 to  connect to the SSH service. After three failed login tries, iptables allows the  host only one login try per minute:

     

    ~# iptables -A INPUT -p tcp -s 193.180.177.13 -m state --syn --state  NEW --dport 22 -m limit --limit 1/minute --limit-burst 1 -j ACCEPT
~#  iptables -A INPUT -p tcp -s 193.180.177.13 -m state --syn --state NEW --dport 22  -j DROP

  • ~# iptables -A INPUT -p tcp -m state --syn --state NEW --dport 22 -m  limit --limit 1/minute --limit-burst 1 -j ACCEPT
~# iptables -A INPUT -p tcp  -m state --syn --state NEW --dport 22 -j DROP

     

    In a second example, iptables are set to allow only host 193.180.177.13 to  connect to the SSH service. After three failed login tries, iptables allows the  host only one login try per minute:

     

    ~# iptables -A INPUT -p tcp -s 193.180.177.13 -m state --syn --state  NEW --dport 22 -m limit --limit 1/minute --limit-burst 1 -j ACCEPT
~#  iptables -A INPUT -p tcp -s 193.180.177.13 -m state --syn --state NEW --dport 22  -j DROP
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