пакеты не могут аутентифицироваться! - traceroute

Я пытаюсь установить traceroute в человечности, и я получаю следующее сообщение.

sudo apt-get install traceroute
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  traceroute
0 upgraded, 1 newly installed, 0 to remove and 6 not upgraded.
Need to get 53.1 kB of archives.
After this operation, 162 kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  traceroute
Install these packages without verification [y/N]? n
E: Some packages could not be authenticated

но когда я устанавливаю в системе своего друга, она хорошо работает.

sudo apt-get install traceroute
[sudo] password for ankit: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  traceroute
0 upgraded, 1 newly installed, 0 to remove and 12 not upgraded.
Need to get 53.1 kB of archives.
After this operation, 162 kB of additional disk space will be used.
Get:1 http://in.archive.ubuntu.com/ubuntu/ precise/universe traceroute amd64 1:2.0.18-1 [53.1 kB]
Fetched 53.1 kB in 1s (28.8 kB/s)     
Selecting previously unselected package traceroute.
(Reading database ... 207690 files and directories currently installed.)
Unpacking traceroute (from .../traceroute_1%3a2.0.18-1_amd64.deb) ...

[1]+  Stopped                 sudo apt-get install traceroute

Что не так в моей системе?

Заранее спасибо.