# network fault - sigle site unreachable only in linux[solved]

## djinnZ

Hi, by some days i have a problem with the linux box (and only with them).

I cant connect only to rapidgator.net. Other hosts and sites are ok and there are no problems with other pc's (M$ OS, not linux).

Of course iptables -F not help.

JD, FF and Konq are unable to connect to the site. Any other site or service work fine.

```
traceroute to www.rapidgator.net (195.211.223.18), 30 hops max, 60 byte packets

 1  router (172.30.0.1)  15.679 ms  15.698 ms  15.845 ms

 2  * * *

 3  151.6.208.2 (151.6.208.2)  58.839 ms  59.321 ms  59.756 ms

 4  151.6.5.114 (151.6.5.114)  60.155 ms  60.544 ms  77.273 ms

 5  151.6.3.66 (151.6.3.66)  77.890 ms  95.854 ms  96.253 ms

 6  * * *

 7  * * *

 8  * * *

 9  * * *

10  * * *

11  * * *

12  * * *

13  * * *

14  * * *

15  * * *

16  * * *

17  * * *

18  * * *

19  * * *

20  * * *

21  * * *

22  * * *

23  * * *

24  * * *

25  * * *

26  * * *

27  * * *

28  * * *

29  * * *

30  * * *
```

```
HOST: dite                        Loss%   Snt   Last   Avg  Best  Wrst StDev

  1.|-- caronte                   0.0%    10    8.8  17.3   0.6  55.3  20.9

  2.|-- 151.6.208.10              90.0%    10  158.7 158.7 158.7 158.7   0.0

  3.|-- 151.6.208.10              80.0%    10   34.3  59.5  34.3  84.7  35.6

  4.|-- 151.6.3.162               30.0%    10   35.8  81.0  23.4 163.5  53.4

    |  `|-- 151.6.5.114

  5.|-- 151.6.3.162               60.0%    10   25.7  66.4  25.7 114.2  40.0

  6.|-- 151.6.169.72              40.0%    10  878.5 875.3 631.0 1049. 142.1

    |  `|-- 151.6.208.10

    |   |-- 151.6.5.114

  7.|-- 151.6.169.72              70.0%    10    4.2 538.0   4.2 839.7 463.6

    |  `|-- 151.6.208.10

    |   |-- 151.6.3.162

  8.|-- 151.6.3.162               80.0%    10  700.6 783.7 700.6 866.8 117.5

    |  `|-- 151.6.208.10

  9.|-- ???                       100.0    10    0.0   0.0   0.0   0.0   0.0

 10.|-- 151.6.5.114               90.0%    10  1659. 1659. 1659. 1659.   0.0

 11.|-- ???                       100.0     9    0.0   0.0   0.0   0.0   0.0
```

```
eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500

        inet 172.30.0.6  netmask 255.255.255.240  broadcast 172.30.0.15

        ether 20:cf:30:e2:59:46  txqueuelen 1000  (Ethernet)

        RX packets 112749  bytes 66383464 (63.3 MiB)

        RX errors 0  dropped 0  overruns 0  frame 0

        TX packets 102211  bytes 10616782 (10.1 MiB)

        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536

        inet 127.0.0.1  netmask 255.0.0.0

        loop  txqueuelen 0  (Local Loopback)

        RX packets 80  bytes 10032 (9.7 KiB)

        RX errors 0  dropped 0  overruns 0  frame 0

        TX packets 80  bytes 10032 (9.7 KiB)

        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
```

```
Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

default         caronte         0.0.0.0         UG    5      0        0 eth1

loopback        localhost       255.0.0.0       UG    0      0        0 lo

172.30.0.0      *               255.255.255.240 U     0      0        0 eth1
```

```
# /etc/conf.d.net

# general

modules="iproute2"

# eth0  - wan interface

config_eth0="172.30.0.14/28"

routes_eth0="default gw 172.30.0.1"

ifdown_eth0="yes"

# eth1  - lan interface

#config_eth1="null"

config_eth1="172.30.0.6/28"

routes_eth1="default gw 172.30.0.1"

ifdown_eth1="no"
```

Thanks in advice for any suggestion to investigate and solve this strange problem.

----------

## djinnZ

up.

I am unable to understand why only one domain and only for the linux box.

The other NICs are disconnected and not used.

----------

## Fitzcarraldo

I had a similar problem on one of my laptops running Gentoo: I could not access the IMDb site, but every other site was browsable. In my case it turned out to be PLPMTUD (Packetization Layer Path MTU Discovery) and I was able to get my browser to view that site: Why can’t I access a specific Web site?. In case it helps.

----------

## djinnZ

Sorry for late answer but changing the MTU or using sysctl to set tcp_mtu_probing not help.

----------

## PaulBredbury

Some other sysctl entries to try:

net.ipv4.tcp_window_scaling=0

net.ipv4.netfilter.ip_conntrack_tcp_be_liberal=1  (info)

----------

## djinnZ

I am really unable to find a reasonable cause to this or why but was */etc/sysctl.conf wrote:*   

> # Disable ECN
> 
> net.ipv4.tcp_ecn = 1

 instead of 0

I am not used to /etc/sysctl.conf, because IMHO /etc/sysctl.d is better but ... sorry for mismatch and thanks for the help.

----------

