Strange network problem

mururoa · #1 **(View Single Post)** 23rd October 2008

Hello,
Since a few weeks I have a strange network problem.
Using firefox or any other browser I have like 10 seconds between the time I enter an address in the address tab and the display of the page.
It always ends working. Just 10 seconds between click and the display.

This seems not be a dns problem since I get instant responses from any dns query.

Code:

[root@mururoa2 ~]# dig +search www.sun.com

; <<>> DiG 9.4.2 <<>> +search www.sun.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 38457
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.sun.com.                   IN      A

;; ANSWER SECTION:
www.sun.com.            167     IN      A       72.5.124.61

;; Query time: 77 msec
;; SERVER: 192.168.0.1#53(192.168.0.1)
;; WHEN: Thu Oct 23 11:02:59 2008
;; MSG SIZE  rcvd: 45

Then I looked with traceroute and oups ! Here what I get :

Code:

[mururoa@mururoa2 /usr/home/mururoa]$ ping www.sun.com
PING www.sun.com (72.5.124.61): 56 data bytes
^C
--- www.sun.com ping statistics ---
2 packets transmitted, 0 packets received, 100.0% packet loss
[mururoa@mururoa2 /usr/home/mururoa]$ traceroute www.sun.com
traceroute to www.sun.com (72.5.124.61), 64 hops max, 40 byte packets
 1  routeur.lan (192.168.0.1)  1.100 ms  0.675 ms  0.657 ms
 2  192.168.1.1 (192.168.1.1)  1.989 ms  1.701 ms  2.014 ms
 3  80.9.20.1 (80.9.20.1)  40.715 ms  41.163 ms  40.313 ms
 4  * 10.125.115.74 (10.125.115.74)  41.359 ms  41.693 ms
 5  193.253.87.206 (193.253.87.206)  41.160 ms  39.432 ms  40.632 ms
 6  193.252.160.162 (193.252.160.162)  42.547 ms  40.325 ms  40.603 ms
 7  193.252.101.225 (193.252.101.225)  40.771 ms  41.020 ms  40.016 ms
 8  193.251.252.137 (193.251.252.137)  47.739 ms  48.227 ms  47.849 ms
 9  193.251.252.138 (193.251.252.138)  46.814 ms  97.189 ms  47.536 ms
10  4.68.109.62 (4.68.109.62)  49.554 ms
    4.68.109.126 (4.68.109.126)  58.552 ms  58.778 ms
11  4.69.137.50 (4.69.137.50)  137.062 ms  130.399 ms  128.844 ms
12  4.69.134.158 (4.69.134.158)  129.069 ms  127.397 ms  128.859 ms
13  4.69.134.189 (4.69.134.189)  130.020 ms  129.126 ms  140.410 ms
14  4.69.132.94 (4.69.132.94)  138.469 ms  132.081 ms  140.214 ms
15  4.69.135.185 (4.69.135.185)  212.779 ms  204.822 ms  211.436 ms
16  4.69.134.242 (4.69.134.242)  208.561 ms  207.176 ms  210.714 ms
17  4.69.134.209 (4.69.134.209)  208.541 ms  204.898 ms  214.558 ms
18  4.69.140.153 (4.69.140.153)  232.661 ms  212.727 ms  214.712 ms
19  4.69.133.157 (4.69.133.157)  204.518 ms  292.273 ms  399.695 ms
20  4.78.242.18 (4.78.242.18)  213.543 ms  212.116 ms  213.510 ms
21  63.251.63.82 (63.251.63.82)  214.407 ms  212.880 ms  213.164 ms
22  * * *
23  * * *
24  * * *
25  * * *
26  * * *
27  * * *
28  * * *
29  * * *
30  * * *
31  * * *
32  * * *
33  * * *
34  * * *
35  * * *
36  * * *
37  * * *
38  * * *
39  * * *
40  * * *
41  * * *
42  * * *
43  * * *
44  * * *
45  * * *
46  * * *
47  * * *
48  * * *
49  * * *
50  * * *
51  * * *
52  * * *
53  * * *
54  * * *
55  * * *
56  * * *
57  * * *
58  * * *
59  * * *
60  * * *
61  * * *
62  * * *
63  * * *
64  * * *

What's this ? 64 hops and host not reached ... But I did reach it and using firefox the page displays.

Here is the routing table :

Code:

[root@mururoa2 ~]# netstat -rn
Routing tables

Internet:
Destination        Gateway            Flags    Refs      Use  Netif Expire
default            192.168.0.1        UGS         0     3045    xl0
127.0.0.1          127.0.0.1          UH          0        0    lo0
192.168.0.0/24     link#3             UC          0        0    xl0
192.168.0.1        00:15:f2:7e:a0:95  UHLW        2     1125    xl0   1195

Internet6:
Destination                       Gateway                       Flags      Netif Expire
::1                               ::1                           UHL         lo0
fe80::%lo0/64                     fe80::1%lo0                   U           lo0
fe80::1%lo0                       link#5                        UHL         lo0
ff01:5::/32                       fe80::1%lo0                   UC          lo0
ff02::%lo0/32                     fe80::1%lo0                   UC          lo0

And I have this problem only using freebsd 7. I have multi-boot and when I use windows XP or linux I dont have this.

What may cause the problem ?

I'll post later traceroute with linux / XP.

DutchDaemon · #2 **(View Single Post)** 23rd October 2008

Not every network on the internet allows traceroute through, so 'not reaching a host' using traceroute doesn't mean a lot. It's just filtered at some border router (my traceroutes end at 63.251.63.17, another pnap router), just like a lot of hosts do not allow ICMP pings through. There are still a lot of people who say that a host is dead just because it doesn't respond to pings.

DutchDaemon · #3 **(View Single Post)** 23rd October 2008

Other than that, seems your ISP (Wanadoo/IP2000) uses a rather weird network setup, involving two/three RFC1918 networks.

What you could try (if you have your own nameserver) is to forward all DNS requests to your ISP's nameservers. The fact that you get a quick reply to www.sun.com is probably because that result is already cached as a result of your earlier visit to that site. Try a dig on some host you've never visited, and see what the response time is to that query. Then try with your DNS requests forwarded to your ISP's nameservers. If you have a lot of latency on your network, a typical external DNS lookup (non-forwarded), which can involve a lot of questions and answers (sometimes more than ten separate queries), suffers a lot.

mururoa · #4 **(View Single Post)** 23rd October 2008

Quote:

Originally Posted by DutchDaemon

Other than that, seems your ISP (Wanadoo/IP2000) uses a rather weird network setup, involving two/three RFC1918 networks.

What you could try (if you have your own nameserver) is to forward all DNS requests to your ISP's nameservers. The fact that you get a quick reply to www.sun.com is probably because that result is already cached as a result of your earlier visit to that site. Try a dig on some host you've never visited, and see what the response time is to that query. Then try with your DNS requests forwarded to your ISP's nameservers. If you have a lot of latency on your network, a typical external DNS lookup (non-forwarded), which can involve a lot of questions and answers (sometimes more than ten separate queries), suffers a lot.

DNS queries works with any domain name.

Like :

Code:

[mururoa@mururoa2 /usr/home/mururoa]$ dig +search www.ibm.com

; <<>> DiG 9.4.2 <<>> +search www.ibm.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28408
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.ibm.com.                   IN      A

;; ANSWER SECTION:
www.ibm.com.            3575    IN      CNAME   www.ibm.com.cs186.net.
www.ibm.com.cs186.net.  35      IN      A       129.42.56.216

;; Query time: 76 msec
;; SERVER: 192.168.0.1#53(192.168.0.1)
;; WHEN: Thu Oct 23 13:05:30 2008
;; MSG SIZE  rcvd: 80

That works with any query.
I dont have a real DNS just a dns cache on my router.

DutchDaemon · #5 **(View Single Post)** 23rd October 2008

When you're waiting for those 10 seconds, what does Firefox show in its status bar? "Connecting to" or "Looking up"? Or are you stuck in "Transferring data"?

phoenix · #6 **(View Single Post)** 24th October 2008

Quote:

Originally Posted by DutchDaemon

Not every network on the internet allows traceroute through, so 'not reaching a host' using traceroute doesn't mean a lot.

Installing tcptraceroute makes things a lot nicer. It uses TCP packets, and you can select which port to use (defaults to 80). It's a lot nicer to be able to use tcptraceroute remote.server 22 to debug connection issues.

mururoa · #7 **(View Single Post)** 27th October 2008

Quote:

Originally Posted by DutchDaemon

When you're waiting for those 10 seconds, what does Firefox show in its status bar? "Connecting to" or "Looking up"? Or are you stuck in "Transferring data"?

It displays "looking up" and there is no dns cache effect. If I go to one site, another and back the first I have each time the 10 seconds.

mururoa · #8 **(View Single Post)** 27th October 2008

Quote:

Originally Posted by phoenix

Installing tcptraceroute makes things a lot nicer. It uses TCP packets, and you can select which port to use (defaults to 80). It's a lot nicer to be able to use tcptraceroute remote.server 22 to debug connection issues.

I will install this one and then look again.

mururoa · #9 **(View Single Post)** 27th October 2008

Well every address I test do more or less the same things :

Code:

[root@mururoa2 ~]# tcptraceroute www.orange.fr 80
Selected device xl0, address 192.168.0.51, port 57027 for outgoing packets
Tracing the path to www.orange.fr (193.252.122.103) on TCP port 80, 30 hops max
 1  192.168.0.1 (192.168.0.1)  9.404 ms  9.915 ms  9.975 ms
 2  192.168.1.1 (192.168.1.1)  9.985 ms  9.990 ms  9.970 ms
 3  80.9.20.1 (80.9.20.1)  39.999 ms * *
 4  10.125.115.74 (10.125.115.74)  41.001 ms * 40.323 ms
 5  193.253.87.206 (193.253.87.206)  39.913 ms * *
 6  81.253.130.166 (81.253.130.166)  40.026 ms * 41.251 ms
 7  193.252.161.154 (193.252.161.154)  49.557 ms  48.362 ms  46.844 ms
 8  * 193.252.161.153 (193.252.161.153) 119.822 ms *
 9  193.252.227.158 (193.252.227.158)  46.702 ms  65.150 ms  47.357 ms
10  193.252.121.173 (193.252.121.173)  47.452 ms  48.230 ms  47.796 ms
11  * * *
12  * * *
13  * * *
14  * * *
15  * * *
16  * * *
17  * * *
18  * * *
19  * * *
20  * * *
21  * * *
22  * * *
23  * * *
24  * * *
25  * * *
26  * * *
27  * * *
28  * * *
29  * * *
30  * * *
Destination not reached

This address (www.orange.fr) is supposed to be my isp main site.
Ofc If I enter this using firefox or konqueror I have the 10 sec delay and then I reach the site.
It seems to be I have some network to learn ...

anemos · #10 **(View Single Post)** 28th October 2008

I can't ping www.sun.com either, nor do i reach it with a traceroute. As DutchDaemon said this is normal.
However, two things seem a bit strange to me.

1. traceroute by default (without -n) displays names - yours doesn't.

2. Why is the first hop 192.168.0.1 and the second 192.168.1.1?

mururoa · #11 **(View Single Post)** 28th October 2008

Quote:

Originally Posted by anemos

I can't ping www.sun.com either, nor do i reach it with a traceroute. As DutchDaemon said this is normal.
However, two things seem a bit strange to me.

1. traceroute by default (without -n) displays names - yours doesn't.

2. Why is the first hop 192.168.0.1 and the second 192.168.1.1?

1 : dunno why it dont display the names. I entered the command displayed.

2 : 192.168.0.1 is the router. 192.168.1.1 is the adsl box

mururoa · #12 **(View Single Post)** 28th October 2008

And this is the tracert on windows XP :

Code:

C:\Documents and Settings\root>tracert www.orange.fr

Détermination de l'itinéraire vers www.orange.fr.multis.x-echo.com [193.252.122.103] avec un maximum de 30 sauts�*:

  1    <1 ms    <1 ms    <1 ms  routeur.lan [192.168.0.1]
  2     2 ms     1 ms     2 ms  192.168.1.1
  3    40 ms    41 ms    41 ms  80.9.20.1
  4    46 ms     *       41 ms  10.125.115.74
  5    41 ms    40 ms    41 ms  193.253.87.206
  6    41 ms    42 ms    41 ms  81.253.130.166
  7    49 ms    48 ms    49 ms  193.252.161.154
  8    47 ms   112 ms    47 ms  193.252.161.153
  9    48 ms    65 ms    47 ms  193.252.227.158
 10    49 ms    49 ms    47 ms  193.252.121.173
 11    56 ms    48 ms    49 ms  193.252.122.103

Itinéraire déterminé.

Same computer, same network card, same router and same adsl box ofc.
No 10 seconds delay on windows XP.

What, the hell, did I broke in FreeBSD ?

anomie · #13 **(View Single Post)** 28th October 2008

This thread is a little chaotic.

First, the DNS problem: Try using your ISP's nameservers in /etc/resolv.conf. Failing that, use the opendns servers.

Second, are you making any sysctl tweaks to IP (or anything network related) on your FreeBSD installation?

Third, don't try pinging www.sun.com - they're dropping icmp echo requests.

Finally, I don't see that you tried a normal traceroute from your FreeBSD box to www.orange.fr.

I'm not convinced there is an actual problem here yet (apart from possible slow name resolution).

mururoa · #14 **(View Single Post)** 3rd November 2008

Oh, there is a problem. No doubt to me. 99% it's related to some FreeBSD configuration I"ve done of my own or due to upgrading process of system or ports. For example it happens I lost the lo0 in the rc.conf. No idea why but I had network_interfaces="xl0" in my rc.conf instead of "xlo lo0".
I'm also 100% sure that if I can reinstall FreeBSD from scratch this problem should disapear but this is an hard work to do. I even could compare my config files before and after and find the problem too.

Anyway here is my rc.conf :

hostname=mururoa2.
ifconfig_xl0=dhcp
keymap="us.iso"
linux_enable="YES"
moused_enable="YES"
sshd_enable="YES"
cupsd_enable="YES"
network_interfaces="xl0 lo0"

About sysctl, no I've done any configuration there and my sysctl.conf is only # xxx.

Oups, declaring DNS servers from my provider solve the problem for good

That dont make me understand why I dont see any problem with windows and linux using same configuration (dhcp) on the same box ...

anomie · #15 **(View Single Post)** 3rd November 2008

Quote:

Originally Posted by mururoa

For example it happens I lost the lo0 in the rc.conf. No idea why but I had network_interfaces="xl0" in my rc.conf instead of "xlo lo0".

It's probably not necessary to override this parameter in /etc/rc.conf. The /etc/defaults/rc.conf file (which you should never change) already contains: network_interfaces="auto"

I get the feeling that you do a fair number of config file changes while troubleshooting. You might look into some form of local version control, e.g. RCS, which is part of the base system.

Quote:

Originally Posted by mururoa

Oups, declaring DNS servers from my provider solve the problem for good

Good news. Now that you've got a working box, you can troubleshoot the how/why of the original problem at your leisure.

mururoa · #16 **(View Single Post)** 5th November 2008

Okay, I'm gonna drop this unneeded network_interfaces in the config files to start but since I'm gonna change MB + CPU I'm gonna suspend this for now.

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