Ubuntu – Unable to access some websites

14.04internetnetworking

I came home for the vacation and realized that I am not able to access certain websites from my laptop. I can't access coursera.org, amazon.in and more sites.

I was able to access them when I was in college from the same laptop but the ISP was different. I had no problem accessing the websites when I came home a few months ago.

I use this laptop to share internet to other devices (my mobile) by following this answer. And strangely enough, my mobile which used the laptop in question as gateway is able to access the websites without any trouble!

Here is the output of traceroute and below given is the output of ifconfig:

eth0      Link encap:Ethernet  HWaddr 74:e6:e2:49:eb:0a
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
RX packets:146357 errors:0 dropped:0 overruns:0 frame:0
TX packets:145046 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:157081182 (157.0 MB)  TX bytes:17192614 (17.1 MB)

UP LOOPBACK RUNNING  MTU:65536  Metric:1
RX packets:132560 errors:0 dropped:0 overruns:0 frame:0
TX packets:132560 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:34805764 (34.8 MB)  TX bytes:34805764 (34.8 MB)


I am running Ubuntu 14.04 and my ISP is BSNL.

• I found out a way to fix the problem. So what can be done is to try reducing the MTU size. From my ifconfig output, it can be seen that MTU is set to 1500. Gradually decrease it to 1492, 1450.. and see if it works.

The command is ifconfig eth0 mtu <MTU> up.

Where <MTU> is the value you want to set. For me everything started working at a MTU value of 1492.

Once you found value that works for you, make the settings permanent. Open /etc/network/interfaces, enter under the correct interface:

mtu <MTU>


where <MTU> is the determined MTU value.