I had a perfectly functioning Ubuntu 12.04 system. I saw a YouTube video from DEFCON where a guy was discussing attacking home routers. In an Internet search of home router security I found a 2011 CERT paper on strengthening SOHO routers. One tip was to reduce the number of IPs on the LAN and to use static IPs.
I went into my 12.04 machine. I set up the static IP address, 192.168.1.7, that I had prepared at the router and lost Internet access. The LAN still works. When I boot to Windows 7, Windows 7 has Internet access. When I go back to DCHP in Ubuntu, reboot, and check I again have LAN access but no Internet access – different IP [192.168.1.11] from DHCP.
I completely reinstalled Ubuntu from a CD – same problem.
I did a search on askubuntu and found 2 previous posts
Wired Internet doesn't work on ubuntu 12.04 from April 29
internet access problem in 12.04 from April 28
I tried those things and they didn't work.
Any ideas, strategies, and tactics for troubleshooting this issue would be much appreciated.
Here are some diagnostics which may be helpful:
ifconfig eth0
eth0 Link encap:Ethernet HWaddr e0:cb:4e:b1:26:dc
inet addr:192.168.1.11 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::e2cb:4eff:feb1:26dc/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1816 errors:0 dropped:0 overruns:0 frame:0
TX packets:2168 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:162945 (162.9 KB) TX bytes:162147 (162.1 KB)
Interrupt:49
route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0
link-local * 255.255.0.0 U 1000 0 0 eth0
192.168.1.0 * 255.255.255.0 U 1 0 0 eth0
cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.0.1
search charter.net
ping -c 4 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
--- 8.8.8.8 ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 3024ms
The output of nm-tool:
NetworkManager Tool
State: connected (global)
- Device: eth0 [Wired connection 1] -------------------------------------------
Type: Wired
Driver: jme
State: connected
Default: yes
HW Address: E0:CB:4E:B1:26:DC
Capabilities:
Carrier Detect: yes
Speed: 1000 Mb/s
Wired Properties
Carrier: on
IPv4 Settings:
Address: 192.168.1.11
Prefix: 24 (255.255.255.0)
Gateway: 192.168.1.1
DNS: 208.67.222.222
DNS: 208.67.220.220
DNS: 192.168.1.1
Results of ping -c 4 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
— 192.168.1.1 ping statistics —
4 packets transmitted, 0 received, 100% packet loss, time 3024ms
Note: This non-response by the router may be because I have set under Security | Firewall | Attack Check | Respond to Ping on Internet Ports [unchecked]. 192.168.1.1 brings up the router login screen on the laptop running Ubuntu 12.04.
I fixed it. Thank you for your assistance. I really appreciate your input on where to look as I tried to resolve this issue.
I went into the UP|Down arrow Icon on the menu bar. This brings up Network Connections. Under the Wired tab I picked Wired Connection 1 and choose [Edit]. That bring up a new options list with 4 tabs. I choose the 3rd Tab [IPv4 Settings].
Choices
Method:Manual
Addresses [Add] Address:192.168.1.7, Netmask:255.255.255.0 Gateway:192.168.1.1
DSN Servers: 208.67.222.222, 208.67.220.220, 192.168.1.1
Search Domains: charter.net
DHCP Client ID: blank – no entry, no change
Require IPv4 addressing for this connection to complete: unchecked – no entry, no change
Routes – brings up a new options listing [Add] Address:192.168.1.7 Netmask:255.255.255.0 Gateway:192.168.1.1 – I left the 2 check box options blank and clicked OK.
Back one screen "Available to all users" [checked] – no change, no entry
Save
Back one screen to Network Connections | Wired
Close
Please excuse me if this fix explanation is too long or detailed. Having searched this resource for answers to questions in the past I know I appreciated when there was more detail. I am new to this forum and don't want to raise the ire of the Sys Admins, Power Users, and the like.
Best Answer
There are two different settings you need to think about - one is for the IP address, and the other is for the DNS address. Automatic DHCP (default) will set both. Your other choices under the IPv4 Settings tab, are:
Automatic (DHCP) addresses only, which sets the IP addresses via DHCP, but allows you to set the DNS addresses yourself, in case you want to use an alternate such as Google or EasyDNS, etc.
Manual, means you set both the IP address and the DNS address. This may be what you selected, and so you have an IP address, but you cannot use domain names, only IP addresses, to connect out, since DNS translates the names to IP addresses.
Under "DNS servers:" in the IPv4 Settings tab, you can enter any number of DNS addresses, separated by commas. For example, if you wanted to use Google's public DNS servers, you would enter
8.8.8.8,8.8.4.4
. If you want to use the same ones as your Windows system, you can check them under Windows using "IPCONFIG", or if you have the original Default network profile (you should), you can switch to that, then enternmcli dev list iface eth0 | grep IP4
at a commandline prompt, and get the DNS addresses (usually 2).Another way is to look into whether your router can assign static IP addresses. I find this to be easier to maintain.
Also, if you're worried about router security, you can probably simply disable external access completely. Most people never use it anyway.