James Nichols a écrit :
On 12/19/07, Eric Dumazet <[email protected]> wrote:
James Nichols a écrit :
So you see outgoing SYN packets, but no SYN replies coming from the remote
peer ? (you mention ACKS, but the first packet received from the remote
peer should be a SYN+ACK),
Right, I meant to say SYN+ACK. I don't see them coming back.
So... Really unlikely a linux problem, but ...
I don't know how you can be so sure. Turning tcp_sack off instantly
resovles the problem and all connections are succesful. I can't
imagine even the most far-fetched scenario where a router or every
single remote endpoints would suddenly stop causing the problem just
by removing a single TCP option.
I can take these captures and take a look at the results.
Unfortunately, I don't think I'll be able to make the captures
available to the general public.
I dont understand, why dont you change IPs to mask them with 192.168.X.Y, or
just ME, and peer1, peer2, peer...
I will see if I can do that, but it's major pain with 2000 hosts.
Plus, there is application data in the packets that I can't allow into
the public domain. I really don't think I can pull it off... I
literally would have to go through our legal department.
I still dont understand.
"tcpdump -p -n -s 1600 -c 10000" doesnt reveal User data at all.
Without any exact data from you, I am afraid nobody can help.
Random ideas :
1) Is your server behind a NET router or something ?
What's a NET router? I am behind a Cisco router and a firewall, but
these network components have completely been replaced/rebuilt several
times in the 4+ years that we've had this problem. I've looked at the
logs there and neither are doing anything other than passing the
traffic along.
Typo error, I meant NAT. Most routers doing NAT have some limits, timers, hacks...
2) Are you sure you are not using connection tracking, and hit a limit on it ?
I'm using ip_conntrack, but the limit I have for max entries is 65K.
The most I've seen in there are a couple thousand- that was one of the
first things I monitored very closely.
Now please try without conn tracking module. I saw many failures in the past
that were trigered by conntrack.
Do you have some firewall rules, using some netfilter modules like hashlimit ?
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