--- Mark Martinec <[EMAIL PROTECTED]> wrote:
> Peter,
>
> > > ICMP type 3 must not be blocked by a firewall!
>
> > Are talking about outbound or inbound ICMP? I allow all outbound
> > traffic to exit unmolested. My f/w is blocking *occasional*
> inbound
> > ICMP type 3 code 1. Meanwhile, disconnections are occurring like
> this:
>
> This is probably unrelated to your immedate problem,
> although it deserves to be put right nevertheless.
>
> I'm talking about both incoming and outgoing ICMP type 3 packets.
>
> Blocked incoming type 3 code 0..3,9..13 packet would cause your
> client
> (Postfix smtp service or any other tcp client such as www, ssh)
> to linger waiting for a connection establishment and eventually
> timing out, while it could otherwise terminate immediately and
> notify user (or log) the actual reason for a reject.
>
> Blocked incoming or outgoing type 3 code 4 packet (Fragmentation
> Needed
> and Don't Fragment was Set) makes max fragment size negotiation
> impossible,
> which manifests in some mail or some web pages being partly
> or fully inaccessible, while others would work normally.
>
> Blocking ICMP type 3 is evil!
Mark,
Thank you for your thorough answer.
It seems that the main problem was the low number of processes I had
allocated to postfix inside master.cf. I changed it from 5 to 150 and
disconnects were reduced dramatically. Those I still register are
either from "unknown" (unresolvable) or from dubiously-named hosts.
But I still get one distressing disconnect:
disconnect from localhost.domain.com[127.0.0.1]
When I look at the context I see:
Jun 4 10:19:32 host postfix/smtpd[23634]: connect from
localhost.domain.com[127.0.0.1]
Jun 4 10:19:32 host postfix/smtpd[23634]: 764E1DD883:
client=localhost.domain.com[127.0.0.1]
Jun 4 10:19:32 host postfix/smtpd[23634]: disconnect from
localhost.domain.com[127.0.0.1]
Where host.domain.com is the name of my machine.
Is this someone trying to spoof my machine?
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