DNS and mail servers behind a PF firewall?
Jacques.Beigbeder at ens.fr
Mon Feb 26 18:46:50 UTC 2007
My question is related to PF performances with large state tables.
FreeBSD : 5.5
hw.model: Intel(R) Xeon(TM) CPU 3.20GHz
hw.physmem: 2138378240 = 2 Gb
If I put a mail server
20 SMTP hits per second (thanks to spam...)
15 seconds per SMTP dialog
90 seconds for PF timeout tcp.close
the state table will have:
20 * (90 + 15) * 2 ways = 5.000 entries
Since any mail generates a few DNS queries (reverse DNS,
+ DSNRBL queries), the state table will also gets
2 ways * 60 seconds (timeout udp.multiple) * 5 (DNS queries) * 20 (connections)
= 12.000 entries
So I'll get around 20.000 entries, each of them have a short lifetime.
. is such a number a performance problem?
It seems strange to constantly add and delete entries for DNS
requests in the state table?
. or do I have to write rules to avoid all the (unnecessary??)
entries? As far as I understand, beginning with
pass in quick proto udp from a.b.c.d port 53 to any
... same for TCP/25 ...
is the trick.
Jacques Beigbeder | Jacques.Beigbeder at ens.fr
Service de Prestations Informatiques | http://www.spi.ens.fr
Ecole normale supérieure |
45 rue d'Ulm |Tel : (+33 1)1 44 32 37 96
F75230 Paris cedex 05 |Fax : (+33 1)1 44 32 20 75
More information about the freebsd-questions