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I have a PC connected to the Internet using an Ethernet connection. Using Ubuntu I am able to resolve domains using nslookup, but if I try to open an internet page, or use wget it doesn't work.

I have used Arch Linux, Mint and Ubuntu Live on two netbooks, all of them unsuccessfully. Windows, however, works just fine.


sudo ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:26:18:80:79:18  
          inet addr:  Bcast:  Mask:
          inet6 addr: fe80::226:18ff:fe80:7918/64 Scope:Link
          RX packets:5751 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2397 errors:0 dropped:0 overruns:0 carrier:17
          collisions:0 txqueuelen:1000 
          RX bytes:659976 (659.9 KB)  TX bytes:253881 (253.8 KB)


route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface   U     1      0        0 eth0     U     1000   0        0 eth0         UG    0      0        0 eth0         UG    202    0        0 eth0


netstat -nr
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface   U         0 0          0 eth0     U         0 0          0 eth0         UG        0 0          0 eth0         UG        0 0          0 eth0


sudo iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination


cat /etc/resolv.conf
# Generated by resolvconf 
search uni-mannheim.de 

tracepath is not working:

sudo tracepath www.google.com
 1:  laptop.local                                          0.342ms pmtu 1500
 1:  no reply
 2:  no reply
 3:  no reply
 4:  no reply


sudo cat /etc/host.conf
# The "order" line is only used by old versions of the C library.
order hosts,bind
multi on


sudo cat /etc/nsswitch.conf
# /etc/nsswitch.conf
# Example configuration of GNU Name Service Switch functionality.
# If you have the `glibc-doc-reference' and `info' packages installed, try:
# `info libc "Name Service Switch"' for information about this file.

passwd:         compat
group:          compat
shadow:         compat

hosts:          files mdns4_minimal [NOTFOUND=return] dns mdns4
networks:       files

protocols:      db files
services:       db files
ethers:         db files
rpc:            db files

netgroup:       nis

nslookup google.com

nslookup google.com

Non-authoritative answer:
Name:   google.com
Name:   google.com
Name:   google.com
Name:   google.com
Name:   google.com
Name:   google.com

wget google.com

wget google.com
--2011-08-17 11:05:01--  http://google.com/
Resolving google.com...,,, ...
Connecting to google.com||:80...

dig google.com

tracepath doesn't work but dig does

dig google.com

; <<>> DiG 9.7.3 <<>> google.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2643
;; flags: qr rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 4, ADDITIONAL: 4

;google.com.            IN  A

google.com.     175 IN  A
google.com.     175 IN  A
google.com.     175 IN  A
google.com.     175 IN  A
google.com.     175 IN  A
google.com.     175 IN  A

google.com.     104161  IN  NS  ns4.google.com.
google.com.     104161  IN  NS  ns3.google.com.
google.com.     104161  IN  NS  ns1.google.com.
google.com.     104161  IN  NS  ns2.google.com.

ns1.google.com.     277325  IN  A
ns2.google.com.     277325  IN  A
ns3.google.com.     277325  IN  A
ns4.google.com.     277325  IN  A

;; Query time: 2 msec
;; WHEN: Wed Aug 17 11:06:14 2011
;; MSG SIZE  rcvd: 260
share|improve this question
Can we see your windows routing table?. You can use route print on the command shell to retrieve it. –  Javier Rivera Aug 17 '11 at 10:40
Can this be a firewall related issue? try stopping the Ubuntu's firewall and let's see what happen. –  Geppettvs D'Constanzo Aug 25 '11 at 19:20

1 Answer 1

up vote 1 down vote accepted

My German is really rusty (been 20 years ...), but based on this information and if you're indeed using uni-mannheim.de network, you need to instruct your software to use their proxy (or just use their vpn). To verify, try

echo "http_proxy = http://www-cache.uni-mannheim.de:3128/" | sudo tee -a /etc/wgetrc
echo "use_proxy = on" | sudo tee -a /etc/wgetrc
wget http://www.google.com/

If this works, you should perhaps use the provided vpn connection instead (it probably supports more protocols). Alternatively, you have to instruct all relevant software to use this proxy.

Don't forget to remove those two lines from /etc/wgetrc once you're done with the testing.

share|improve this answer
That was indeed the problem, thank you! I still don't understand why windows manages to autoconfigure the proxy while linux gets stuck... Thank you for your time! –  Francesco Aug 26 '11 at 9:53

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