Problems with FreeBSD

[Giorgos Keramidas]

On Tue, 4 Nov 2008 11:10:25 -0200, "J MPZ" <joompz at gmail.com> wrote:
> Hi Paul,
>
> When my connections freeze, I open the tcpdump in other terminal. If I type
> something, type "Enter", on the terminal frozen, the tcpdump show packets,
> like that:
>
> 11:18:45.526256 IP (tos 0x0, ttl  51, id 651, offset 0, flags [DF], proto:
> TCP (6), length: 112) 189.21.230.195.20787 > 201.57.5.2.2264: P 193:241(48)
> ack 0 win 15136 <nop,nop,timestamp 1556398494 745829191,nop,nop,sack 1
> {1428:1664}>
[...]

> I'm using: tcpdump -nvvv -i ste0 host REMOTE_IP

Can you try capturing the connection setup packets, so we can look at
the TCP MSS negotiation values?  Starting TCPDUMP *before* one of the
connections that stall is made should capture that.

There may be an intermediate router or firewall that blocks ICMP and
ends up breaking path MTU discovery.  I've seen TCP connections
'stall' when path-mtu was broken by a setup like this and one of the
intermediate routers started dropping TCP packets that were too large
for one of its interfaces.