Re: Why does Debian allow all incoming traffic by default
Pascal Hambourg wrote:
> Le 21/09/2018 à 19:09, Dan Ritter a écrit :
>>
>> Let's suppose Debian installs a basic firewall by default. How
>> basic? Let's say:
>>
>> - outbound: permit
>> - forward: deny
>> - inbound: accept NTP, DHCP, DNS, and any TCP packet which is a
>> response to an outbound packet
>
> Why should unsolicited NTP, DHCP and DNS inbound packets be allowed ?
In my case, the box is running as a server for those protocols. Though,
Gene (or others) may do things differently. NOTE -I only listen for
unsolicited requests on the LAN for those.
Only stuff on the internet is SSH and SMTP.
>
> Why should only TCP inbound responses be allowed ? What about UDP-based
> protocols, ping replies (ICMP echo reply), ICMP error messages, and so on ?
DNS is UDP (er, by default; though it can use TCP). ICMP echo would
most likely fall under the "response to something outbound".
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