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Old 04-08-2011, 06:05 AM   #1
igadoter
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Registered: Sep 2006
Location: wroclaw, poland
Distribution: slack 12.2, debian-Trinity , openbsd
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Problem with network connection under 12.2


Hi,
I've got a problem which drives me crazy. There is a website I am unable to connect (and a server). This problem appears only when I am workin at home, using my wifi network with my wifi router. Why am I becoming mad? I have four other systems: W2000, WXP, OpenBSD, Debian, they all use the same wifi router for a connection and there is no problem at all. It is not related to that particular computer cause eg. OpenBSD is installed on the same computer, it uses the same wifi card (so no some kind of a MAC filtration on the side of the router) and working on OpenBSD I can connect.

For me it seems that accidentally I set some kind of a wall in the Slackware. But where and how? Where should I look for some filters or settings which may cause such strange behaveour?

Let me be clear: it is only about that particular site, I have an internet connection, I can google, I can do all thing, but I'm unable to connect to exactly this one site.

Yeah, you know I always said that all companies should employee me as a super alfa tester. I'm able to broke everything. No system is secure when I'm working on it.
 
Old 04-08-2011, 06:09 AM   #2
repo
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Perhaps you can post the website?
Try this
Code:
echo 0 > /proc/sys/net/ipv4/tcp_window_scaling

Kind regards
 
Old 04-08-2011, 02:54 PM   #3
Woodsman
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Quick checks:

Can you ping the web site URL? If you can then the problem is in the browser and not the system.

If the ping reveals an IP address of 127.0.0.1 (local host), then check /etc/hosts is not redirecting that particular web site to localhost (127.0.0.1). If you use dnsmasq, check that you do not have that web site redirected to localhost using a secondary hosts file.

If the ping is successful then deal with the browser.

Are you using any kind of ad blocking software where that particular web site might have inadvertently been added? Temporarily disable any such add-on.

You might be blocking by IP address. So find the IP address for that web site URL:

dig +short websiteurl

The dig command will bypass any local hosts file.

You could grep the entire /etc and $HOME directories looking for that web site URL. That might reveal something.

grep -r -i "websiteurl" /etc
grep -r -i "websiteurl" $HOME

Don't use the www prefix or .com suffix in the search.

Likewise for any IP address.
 
Old 04-08-2011, 03:33 PM   #4
igadoter
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Registered: Sep 2006
Location: wroclaw, poland
Distribution: slack 12.2, debian-Trinity , openbsd
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Original Poster
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Here are all details.
Code:
bash-3.1
#iwconfig eth1
eth1      IEEE 802.11b  ESSID:"piotr"  Nickname:"(none)"
          Mode:Managed  Frequency:2.417 GHz  Access Point: 00:06:4F:85:B5:46
          Bit Rate=11 Mb/s   Tx-Power:16 dBm
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Encryption key:C890-24FC-9856-4C56-5B1F-550E-F0E8-E553-2BFC-8F2A-02D3-B490-E9F5-371E-FF80-A622   Security mode:open
          Power Management:off
          Link Quality=100/100  Signal level=-50 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:46   Missed beacon:0
Code:
bash-3.1# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:0c:f1:30:2e:62
          inet addr:192.168.1.101  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:f1ff:fe30:2e62/64 Scope:Link
          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:960 errors:44 dropped:0 overruns:0 frame:0
          TX packets:893 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:806523 (787.6 KiB)  TX bytes:184673 (180.3 KiB)
          Interrupt:11 Base address:0xe000 Memory:d0201000-d0201fff
198.162.1.100 is a local IP of the router. Let try to ping that mysterious server
Code:
ping -I eth1 alfa.im.pwr.wroc.pl
--- alfa.im.pwr.wroc.pl ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4017ms
rtt min/avg/max/mdev = 22.068/23.856/26.880/1.700 ms
it works. Let do ssh connection
Code:
bash-3.1# ssh -l foo alfa.im.pwr.wroc.pl
ssh: connect to host alfa.im.pwr.wroc.pl port 22: No route to host
Doesn't work. Let do this more tricky. Nearby is my second computer with Debian running
Code:
piotr@debian:~$ ssh -l foo alfa.im.pwr.wroc.pl
foo@alfa.im.pwr.wroc.pl password:
Hmm works, so there is no firewalls on the router neither the remote server using some filters (im ignorant, I know)
So let connect my notebook with Slackware directly with the box running debian
Code:
bash-3.1# ifconfig eth0 192.168.0.1
On the debian side
Code:
ifconfig eth0 192.168.0.2
Now I can connect to the remote server from slackware
Code:
bash-3.1# ssh -l foo alfa.im.pwr.wroc.pl
The authenticity of host 'alfa.im.pwr.wroc.pl (156.17.7.2)' can't be established.
RSA key fingerprint is 78:05:b8:37:69:50:23:43:a6:b9:77:1d:c6:9a:93:d1.
Are you sure you want to continue connecting (yes/no)?
Seems the debian box works as a some kind of a gateway? Let check
Code:
bash-3.1# traceroute -i eth1 alfa.im.pwr.wroc.pl
traceroute to alfa.im.pwr.wroc.pl (156.17.7.2), 30 hops max, 38 byte packets
 1  ROUTER (192.168.1.100)  2.047 ms  2.503 ms  2.665 ms
 2  dynamic-78-8-134-1.ssp.dialog.net.pl (78.8.134.1)  25.663 ms  21.521 ms  20.655 ms
 3  r-1-crs-TE0104-wro.wroclaw.dialog.net.pl (62.87.132.149)  20.445 ms  22.342 ms  20.998 ms
 4  r-1-br-TE0300-wro.wroclaw.dialog.net.pl (217.30.128.154)  22.688 ms  27.985 ms  21.934 ms
 5  wask-dialog.wask.wroc.pl (212.127.66.14)  23.281 ms  21.839 ms  36.097 ms
 6  156.17.250.223 (156.17.250.223)  20.481 ms  22.656 ms  20.571 ms
 7  centrum-karkonosz.wask.wroc.pl (156.17.254.110)  24.643 ms  22.314 ms  22.353 ms
 8  z-wask2-do-pwr2.pwrnet.pwr.wroc.pl (156.17.18.244)  22.423 ms  23.021 ms  22.887 ms
 9  z-pwr2core-do-pwr3core.pwrnet.pwr.wroc.pl (156.17.18.233)  24.629 ms  23.481 ms  25.343 ms
10  alfa.im.pwr.wroc.pl (156.17.7.2)  26.865 ms  24.102 ms  21.480 ms
Hmm, seems the connection is made by wifi card, so let disconnect debian box. Still works - debian is a cure for
everything. Great let reboot slackware
Code:
bash-3.1$ ssh -l foo alfa.im.pwr.wroc.pl
ssh: connect to host alfa.im.pwr.wroc.pl port 22: No route to host
Oh, no, no, aarrrghhh. Am I dead? Silence of stupid lambs?
 
Old 04-08-2011, 08:38 PM   #5
allend
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Is it not good that ssh is working exactly as you would want so as to avoid a MITM compromise?

You are using ssh with key authentication. Your two machines have different host keys.
 
Old 04-08-2011, 10:52 PM   #6
Woodsman
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Distribution: Slackware 14.1
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Quote:
No route to host
Quote:
Seems the debian box works as a some kind of a gateway?
What do have assigned as the gateway for your Slackware machine? (/etc/rc.d/rc.inet1.conf, GATEWAY=???)

You wrote that your router IP address is 192.168.0.100. You wrote when you connected the Debian box (IP=192.168.0.2) that you could connect. Is /etc/rc.d/rc.inet1.conf, GATEWAY assigned to 192.168.0.2 rather than 192.168.0.100?

You might also want to check /etc/hosts.allow and /etc/hosts.deny?

Last edited by Woodsman; 04-08-2011 at 10:55 PM.
 
Old 04-10-2011, 06:12 AM   #7
igadoter
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Registered: Sep 2006
Location: wroclaw, poland
Distribution: slack 12.2, debian-Trinity , openbsd
Posts: 729

Original Poster
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Ok,
I solved this. My eth0 interface has permanently assigned 156.17.7.194 IP. I mean the system during the boot assignes this IP via rc.inet1 script. The server IP I want to connect to is 156.17.7.2 - the addresses are so close that the kernel routes only using eth0 (in the same pool of local addresses). To get a connection it's enough to change the IP for eth0.
 
  


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