[Mimedefang] Locking down sendmail from behind a filtering gateway

John Von Essen john at quonix.net
Thu Feb 19 10:26:17 EST 2015


Kees,

Would 

Connect:IPv4		REJECT

Also work? That would make a lot cleaner of a setup. Its a live production server, so I have to find a time to test the syntax.


Thanks
John


On Feb 17, 2015, at 4:33 PM, Kees Theunissen <C.J.Theunissen at differ.nl> wrote:

> On Tue, 17 Feb 2015, John Von Essen wrote:
> 
>> Initially I thought I could do this with the access table, i.e.
>> 
>> Connect:1		REJECT
>> Connect:2		REJECT
>> ?
>> ?
>> Connect:254		REJECT
>> Connect:127.0.0.1	OK
>> Connect: X.X.X.X	OK
>> 
>> Where X.X.X.X is the IP of my filtering gateway. I ?think? the above
>> works, I did it once before a long time ago. But the problem is my mail
>> server is also IPv6, so doing the above for IPv6 is not practical.
>> 
>> Any thoughts, the filtering gateways only have 1 NIC. Worst case, I can
>> put a firewall on the mail server, but I didn?t want to have to do that.
>> Is there a way to make sendmail deny everything by default?
> 
> 
> Not tested but the line below should work as catch-all rule for IPv6.
> 
> 
> Connect:IPv6	REJECT
> 
> 
> 
> Regards,
> 
> Kees Theunissen.
> 
> -- 
> Kees Theunissen,  System and network manager,   Tel: +31 (0)30 6096724
> Dutch Institute For Fundamental Energy Research (DIFFER)
> e-mail address:   C.J.Theunissen at differ.nl
> postal address:   PO Box 1207, 3430 BE Nieuwegein, NL
> visitors address: Edisonbaan 14, 3439 MN Nieuwegein, NL
> 
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