Connection problems with fedora

I'm having problems with network connections using fedora core 2
(kernel
2.6.6-1.435.2.3). The high-level symptom is that the first attempt to
connect (e.g. to a web server) fails. Mozilla reports "the document
contains no data" but in fact it never manages to connect at all.
Subsequent connections, within a short space of time, succeed.

The problem seems to be DNS related; a typical tcpdump looks like this
(give or take some line wrapping):

21:28:20.845090 IP 192.168.2.5.33003 > 158.152.1.58.domain: 54551+%
[1au] AAAA? www.slashdot.org. (45)
21:28:21.015888 IP 158.152.1.58.domain > 192.168.2.5.33003: 54551
0/1/1 (104)
21:28:21.020332 IP 192.168.2.5.33003 > 158.152.1.58.domain: 62726+%
[1au] A? www.slashdot.org. (45)
21:28:21.043524 IP 158.152.1.58.domain > 192.168.2.5.33003: 62726
1/0/1 A 66.35.250.151 (61)
21:28:21.047347 IP 192.168.2.5.33003 > 158.152.1.58.domain: 15707+%
[1au] PTR? 151.250.35.66.in-addr.arpa. (55)
21:28:21.073796 IP 158.152.1.58.domain > 192.168.2.5.33003: 15707
2/0/1 CNAME 151.0/24.250.35.66.in-addr.arpa., PTR star.slashdot.org.
(109)
21:28:21.076798 IP 192.168.2.5.33003 > 158.152.1.58.domain: 61215+%
[1au] PTR? 151.0/24.250.35.66.in-addr.arpa. (60)
21:28:21.104036 IP 158.152.1.58.domain > 192.168.2.5.33003: 61215
1/0/1 PTR star.slashdot.org. (91)
21:28:25.844215 arp who-has 192.168.2.2 tell 192.168.2.5
21:28:25.844728 arp reply 192.168.2.2 is-at 02:60:8c:a9:c5:2b
21:28:37.568876 IP 192.168.2.5.33499 > 66.35.250.151.http: S
3520411629:3520411629(0) win 5840 <mss 1460,sackOK,timestamp 78396936
0,nop,wscale 0>
21:28:37.743009 IP 66.35.250.151.http > 192.168.2.5.33499: S
66478419:66478419(0) ack 3520411630 win 5792 <mss
1460,sackOK,timestamp 31212595 78396936,nop,wscale 0>
21:28:37.743108 IP 192.168.2.5.33499 > 66.35.250.151.http: . ack 1 win
5840 <nop,nop,timestamp 78397110 31212595>


... and away it goes.

The fedora box is 192.168.2.5, the default router (a RH9 box) is
192.168.2.2, and my ISP's name server (or one of them) is
158.152.1.58.

This is using BIND running locally, but the effect is the same if I
bypass that by editing resolv.conf to point at 158.152.1.58. There's
an
ADSL router and a 512k broadband connection the other side of the RH9
box.
It worked fine until I upgraded what's now the fedora box from RH9.

Three questions:

1. Has anyone else seen this, or is it just me?

2. Does anyone know how to stop it looking for IPV6 addresses? - seems
an obvious thing to try but I don't know how

3. Has anyone any ideas on where to look next?




Peter Greenwood

Peter Greenwood wrote:
> I'm having problems with network connections using fedora core 2
> (kernel
> 2.6.6-1.435.2.3). The high-level symptom is that the first attempt to
> connect (e.g. to a web server) fails. Mozilla reports "the document
> contains no data" but in fact it never manages to connect at all.
> Subsequent connections, within a short space of time, succeed.
>
> [snip]
>
> Three questions:
>
> 1. Has anyone else seen this, or is it just me?
>
> 2. Does anyone know how to stop it looking for IPV6 addresses? - seems
> an obvious thing to try but I don't know how
>
> 3. Has anyone any ideas on where to look next?

I've seen other folks complain about it, but I haven't experienced it.

Putting
alias net-pf-10 off
in /etc/modprobe.conf will stop the ipv6 module from loading on boot.

Allen Kistler <(E-Mail Removed)> wrote in message ok next?
>
> I've seen other folks complain about it, but I haven't experienced it.

Any idea where? I can't find anything - probably using the wrong search
terms or something. I've looked in newsgroups and the fedora mailing
list archives; no luck.

> Putting
> alias net-pf-10 off
> in /etc/modprobe.conf will stop the ipv6 module from loading on boot.

Thanks - yes it stops it trying to resolve IPV6 addresses, unfortunately
that doesn't help


Peter

Peter Greenwood wrote:

> 2.6.6-1.435.2.3). The high-level symptom is that the first attempt to
> connect (e.g. to a web server) fails. Mozilla reports "the document
> contains no data" but in fact it never manages to connect at all.
> Subsequent connections, within a short space of time, succeed.

> 2. Does anyone know how to stop it looking for IPV6 addresses? - seems
> an obvious thing to try but I don't know how

Right there is your problem. FC2 comes with ipv6 enabled by
default. Mozilla prioritises ipv6 over ipv4. Thus, mozilla
realises it's on an ipv6-enabled host and begins by looking
up the AAAA record for the host (website) you are trying to
visit. With some bad luck that host has an ipv6 address
(slashdot does), so mozilla gets an answer and tries to
connect. That fails, because you have no ipv6 connectivity,
so mozilla ends up hanging for a while, then gives up and
goes for the ipv4 address.

Do rmmod ipv6, restart mozilla and see if the problem goes
away. If it does, comment out the line 'alias net-pf-10 ipv6'
in your modprobe.conf.

Z