I am using a proxy to connect to internet. I can use firefox and software center. but can not ping google. when I try it says

ping google.com

ping: unknown host google.com

I have tried with ip address also. it says Destination Host Unreachable.

please help. Thanks in advance.

  • That doesn't matter in this case... – s3lph Mar 2 '14 at 15:44
  • yes, You are right. I found that I am also suffering from same problem. – g_p Mar 2 '14 at 15:46
  • If you're accessing through proxy.. then have you tried applying proxy system wide under network... :) – AzkerM Mar 2 '14 at 15:50
  • Little strange problem. I can ping when I am connected using ppp interface but can't when using my samsung wave mobile wifi hotspot. – g_p Mar 2 '14 at 15:55
  • I guess the phone accesses the internet via 3G etc. so you don't need the proxy there – s3lph Mar 3 '14 at 17:04

For bash commands you have to set the proxy seperately. For this, you have to set a environment variable, e.g.:

ping google.com    # can't resolve, no proxy set
export http_proxy=proxy.example.com:1234
ping google.com    # works, proxy set for this bash session.

Replace the address and the port with your proxy configuration. If you're always behind this proxy, add the export http_proxy... command to ~/.bashrc so it gets executed every time you start a new bash session.

Or to execute a single command with proxy settings and without setting environment variables, use env, e.g.:

env http_proxy=proxy.example.com:1234 ping google.com
sudo env http_proxy=proxy.example.com:1234 apt-get install cowsay

To use other services, e.g. HTTPS or FTP you have to set different variables:

export https_proxy=proxy.example.com:1234
export ftp_proxy=proxy.example.com:1234
  • 1
    This seems to contradict superuser.com/a/175441/269366. Has ping gained new functionality? – Carsten S Sep 13 '15 at 16:20
  • Actually, the SU answer is only partially correct: While the ICMP protocol itself is on the IP layer, the ping utility itself operates on the application layer. My CS teacher once had some problems in explaining this properly, and simply declared ping as a hybrid of ISO/OSI layer 3 and 7. – s3lph Sep 13 '15 at 18:50
  • Thanks for the reply. I still do not see how an http proxy should help, but I do not currently have access to a system where I could test this. – Carsten S Sep 13 '15 at 19:09
  • 1
    This doesn't work! I am behind institute proxy and have set the environment variables correctly. But can't ping google.com "unknow host" – rootkea Feb 27 '17 at 16:48

Try this:

Open a terminal. Ctrl + Alt + T

Run it:

$ sudo -i
# nano /etc/bash.bashrc

Put the following lines in the file:

export http_proxy=http://my_proxy_server:3128/
export https_proxy=http://my_proxy_server:3128/
export ftp_proxy=http://my_proxy_server:3128/
export socks_proxy=socks://my_proxy_server:3128/

Ctrl + U, paste. Ctrl + O, save file. Ctrl + X, close nano.

$ sudo -i
# nano /etc/environment

Put the following lines in the file


Ctrl + U, paste. Ctrl + O, save file. Ctrl + X, close nano.

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