[Lula] Mail server ip changed issue.

[Peter Benjamin]

At 02:02 PM 6/29/2006, you wrote:
>Wow, re-do your calculation.  

Yes, you're right.

>Sure, an ethernet packet can be 1500 bytes,

MTU is 1506 right?  That would be the data packet size from the
sending email client, I think.

> but if the layer 7 payload is 1 byte, the packet will not be 1500 bytes.  

Oh, not the packet, but number of packets changes from 1 packet
of size 1506, to 1506 packets with a data payload size of 1,
if I correctly understood your description of spamd.

>What is the size of the IP header?  I don't remember exactly but it's no more than 80 bytes.  I think it's under 40 bytes.  

5 words or 8, is 40 bytes (my recall).

So, the total data packet size is now 41 bytes, times
1506 packets, for a total of 61746 bytes, compared to
1506 bytes, an increase of a factor of about 40, not 1500.

>I could look it up but laziness prevails.  And for another thing, I don't get a steady, unending stream of email to my home server.  

Oh, not yet.

>Read up on OpenBSD's spamd.  I'm sure you'll see it doesn't really consume very much bandwidth.  It also responds slowly so less traffic is encouraged to come in on a connection.  I think it tries to get it down to one packet per second.

Things have "changed" since I learned TCP, incompletely at that,
a decade ago or more.  So, please do correct my understanding below.
Read it all before replying to save yourself typing time.

Oh, yes, using the TCP layer for ACKing the reception of the 41 byte
packet, could be limited.  But that does not mean the sending
computer, or rather the router that needs to repacket from the
MTU of 1506 down to a packet size of 1, is going to wait for the
ACK...

And whose router is likely going to get hammered?  Your ISP's?

Or is the thought that spamd's request for a data size of 1 byte,
is going to go all the back to the mail client computer or it's
upstream router, where the data size will change?

>For anybody else who wants to set up these country based lists, see blackholes.us.  Oh and I have some shell scripts for converting their data into BIND zone files.  Let me know if anybody is interested.

Turns out 80% of spam, in one case, is coming from China (*.cn).
And having such a script work work out for me.


_______________________________________________
Lula mailing list
Lula at lula.org
http://www.lula.org/mailman/listinfo/lula