Blocking ICMP with ipchains

From: wwebbat_private
Date: Tue Jan 11 2000 - 16:18:59 PST

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    I've heard that it is not wise to block all ICMP operations.  Such 
    being the case, which of these ICMP operations are safe to block 
    without causing serious problems: 
    
    echo-reply (pong)
    destination-unreachable
       network-unreachable
       host-unreachable
       protocol-unreachable
       port-unreachable
       fragmentation-needed
       source-route-failed
       network-unknown
       host-unknown
       network-prohibited
       host-prohibited
       TOS-network-unreachable
       TOS-host-unreachable
       communication-prohibited
       host-precedence-violation
       precedence-cutoff
    source-quench
    redirect
       network-redirect
       host-redirect
       TOS-network-redirect
       TOS-host-redirect
    echo-request (ping)
    router-advertisement
    router-solicitation
    time-exceeded (ttl-exceeded)
       ttl-zero-during-transit
       ttl-zero-during-reassembly
    parameter-problem
       ip-header-bad
       required-option-missing
    timestamp-request
    timestamp-reply
    address-mask-request
    address-mask-reply
    
    Thanks for any assistance.
    



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