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[Crakem]

Maybe you can try to set off SYN cookies and see if it just solves the problem

I just removed syncookies from TCP configuration.
Hard disk in my server has a standard partitioning schema, first partition is 1Gb swap (too much for this server, I know!) but server has only 64mb RAM, I'm building a cluster and always doing partitions like this way. Running normally I got, with top,

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top - 00:58:43 up 26 days, 22:09,  1 user,  load average: 0.98, 0.68, 0.62
Tasks:  48 total,   1 running,  47 sleeping,   0 stopped,   0 zombie
Cpu(s):  8.2%us, 11.5%sy,  0.7%ni, 76.6%id,  0.7%wa,  0.7%hi,  1.6%si,  0.0%st
Mem:     61288k total,    59508k used,     1780k free,      684k buffers
Swap:  1030160k total,    48284k used,   981876k free,     7852k cached
This server running only with amuled has always 60% load. I'm detecting SYN flood warnings, before seeing log, because load; it increase to 300%
Please what I have to look for?

Another question I didn't understand...

Why on SYN flood warning I only got 20 connections with netstat?

Last SYN flood warning I got cpu was spend  80%wa (amuled didn't reach its usual 50%)

[Crakem]

Solutions:
1 ) Decrease your swap to max 2x real memory. More is useless, and often problematic.

Yes, easy

2) Free as much memory as possible: disable all useless daemons (perhaps some useful one too), tailor and recompile your kernel to your needs, make up something.

I couldn't free more resources here.

3) Buy more memory and install it.

I seriously thinking to update my server in few moths (It's a K6-II memory is SDRAM PC100 no available at normal prices)

I removed SYN cookies and system become more stable. System don't hang but I continue getting rare logs with amulecmd (statistics)
 

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>   Active Connections (estimate): 127
 >   Max Connection Limit Reached: 279543 : 2008-05-20 05:39:18
 >   Average Connections (estimate): 127.728
 >   Peak Connections (estimate): 5884

Thanks you iz0bbz