Great Circle Associates Firewalls
(July 1996)
 

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Subject: Re: Request for Advice
From: bobk @ manzanita . DEV . 3Com . COM (Bob Konigsberg)
Date: Wed, 24 Jul 96 09:38:16 PDT
To: firewalls @ GreatCircle . COM, swapple @ CAM . ORG

Here's some quickie suggestions.  I'm sure others will contribute as well.

Passwords in general
o Always use passwords that incorporate numbers and ! @
 #$%^&*()_+=
  Example: lunch @
 12 
o Limit who gets the passwords
o Use different passwords for different classes of systems.  Don't
  set your router password and personal login to use the same one.
 
 Routers
o Change the passwords regularly
o Don't allow any back doors (usually router-to-router)
o Allow only telnet access on the inside.
o If you're really paranoid, allow only console access, and run that
  through a comm/terminal server with a separate (logged) access control

 Firewalls
o Make sure the firewall host is secured completely aside from the firewall
  config itself.
o Use a packet filtering router to control what even gets to the firewall
  (see above)
o Change your password regularly
o For Firewall authenticated access, use an encrypted access method, 
  no clear passwords.
o Define the services you will allow both on a general and special-user basis
  before you set up shop.
o Log all rule violations to either a separate (secure) machine, or write-only
  media (WORM, CD-ROM, Paper)

 Authentication Servers
o Change passwords regularly
o Log all transactions.
o Limit who is allowed to enter changes to the system (new names, etc.)

Remote Access servers
o Don't identify your organization in the welcome string
  Use welcome phrases like "Welcome to Remote Access server #1"
o Log all login successes, failures, login times, durations, etc.  
  The amount of information you can glean from these is amazing.



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