Problem resolving host

sd|| · 05-09-2010, 04:37 PM

i have internet connection on my laptop through a proxy server,

i set system wide proxy settings and got my web browsers working fine but there is a problem with getting internet connection on my terminal. There is no problem updating some software like netbeans.

Code:

[idlecool@hackbox ~]$ ping google.com
ping: unknown host google.com

what should i do? How can i resolve this issue?

Tinkster · 05-09-2010, 06:01 PM

proxy is just that - an application layer tool to handle a given type of
requests. It handles http/https. ping is not tcp, it's low-level ip, and
the proxy knows nothing about it. To be able to ping you need a default
router/gateway set-up, and its firewall needs to permit your ICMP traffic.

Cheers,
Tink

alli_yas · 05-10-2010, 03:33 AM

Do the following:

Code:

#nslookup www.google.com

If you get something along the lines of "Destination Host Unreachable" then you need to check your gateway settings (/etc/sysconfig/network) and dns settings (in /etc/resolv.conf)

As per Tink, your proxy will only apply to specific protocols like HTTP, HTTPS, FTP etc.

Thanks,
Yas

sd|| · 05-10-2010, 07:38 AM

my main concern is yum is not working...

This is the output.

Code:

[idlecool@hackbox ~]$ sudo nslookup www.google.com
Server:         172.16.111.4
Address:        172.16.111.4#53

** server can't find www.google.com: NXDOMAIN

[idlecool@hackbox ~]$

I have complete control over my system but not on the router or proxy server as i am using my university wifi network. Is there any way to solve this issue.

alli_yas · 05-10-2010, 07:53 AM

Well you wouldn't need to control either the proxy/router - you'd only need access to your proxy server (that is a username/password - which I assume you've configured?)

Post the output of:

Code:

# cat /etc/resolv.conf
# cat /etc/sysconfig/network
# cat /etc/sysconfig/network-scripts/ifcfg-eth0

Are you using DHCP? If so, then the OS should automatically pick up your DNS and set up correctly when you boot/bring up networking.

Cheers
Yas

sd|| · 05-10-2010, 08:07 AM

this is the output

Code:

[idlecool@hackbox ~]$ cat /etc/resolv.conf
# Generated by NetworkManager
domain srmu.edu
search srmu.edu
nameserver 172.16.111.4
[idlecool@hackbox ~]$ cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=hackbox.cynosore.com
[idlecool@hackbox ~]$ cat /etc/sysconfig/network-scripts/ifcfg-eth0
# Marvell Technology Group Ltd. 88E8040 PCI-E Fast Ethernet Controller
DEVICE=eth0
HWADDR=FF:FF:FF:FF:FF:FF
BOOTPROTO=dhcp
TYPE=Ethernet
IPV6INIT=no
ONBOOT=no
USERCTL=no
DEFROUTE=yes
PEERDNS=yes
PEERROUTES=yes
NAME="System eth0"
UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03
[idlecool@hackbox ~]$ 
[idlecool@hackbox ~]$ cat /etc/sysconfig/network-scripts/ifcfg-wlan0
# Intel Corporation PRO/Wireless 4965 AG or AGN [Kedron] Network Connection
DEVICE=wlan0
HWADDR=FF:FF:FF:FF:FF:FF
BOOTPROTO=dhcp
TYPE=Wireless
IPV6INIT=no
ONBOOT=no
USERCTL=no
[idlecool@hackbox ~]$

Yes! the systems automatically does all the connectivity i.e. connecting to the wifi router.

bsat · 05-10-2010, 10:44 AM

type export on the terminal and check the output for the values of http_proxy and ftp_proxy

you might have to set the environmental variables http_proxy and ftp_proxy with respect to your connections

alli_yas · 05-11-2010, 04:18 AM

My advice at this stage is to contact your network administrator.

From what I can see there is no configuration issue - but your box for some reason cannot resolve host names. The proxy would not return this kind of error - but rather something like "Unable to connect" or "Connection Refused".

Maybe your DNS is down/not working - and you need to change to a different DNS - which your admin could help you with.