Hi,
I'm pretty new to business-level routers (I have programming and certain Ubuntu system admin experience though) but I'm facing a problem with Cisco 4431 router.
We have a client with quite strict security policy. The router resides in client's network, with external IP (12.34.56.78) assigned by client's network. The router manages a few Ubuntu servers with v16.04 (X, Y, Z, etc).
From my computer at my home, I can log into client's VPN and then access the router with ssh command, like
>ssh admin@12.34.56.78
or access server X with command like
>ssh -p 2210 guest@12.34.56.78
When I ssh into X, I issue command
>wget https://www.gnu.org/software/wget # I have wget installed actually, just to test internet connection
I got error like
>wget: unable to resolve host address: 'ftp.gnu.org'
Previously I thought the issue was due to the firewall. Please refer to my previous post:
https://community.cisco.com/t5/routing/commands-to-check-internet-connection-for-cisco-4431-integrated/m-p/3860660/highlight/false#M315434
I think I've set the networking files like "interfaces" correctly on server X, like below
user@reporter:/etc/network$ more interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
source /etc/network/interfaces.d/*
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eno1
iface eno1 inet static
address 192.168.2.10 -------------Note: this is the internal IP of the server I'm on now
gateway 192.168.2.1 -------------Note: this is the internal IP of the router
netmask 255.255.255.0
dns-nameservers 127.0.0.1 --------------Note: I also tried 72.30.35.9, 8.8.4.4, 8.8.8.8, and the IP my client gave. Every time I change the IP here. I issue command "sudo service networking restart" But all IPs have the same results: cannot ping www.yahoo.com but positive for 72.30.35.9
With this, I can ping IP, like
user@reporter:/etc/network$ ping 72.30.35.9 -------------Note: I try to ping Yahoo IP, works
PING 72.30.35.9 (72.30.35.9) 56(84) bytes of data.
64 bytes from 72.30.35.9: icmp_seq=1 ttl=49 time=25.7 ms
64 bytes from 72.30.35.9: icmp_seq=2 ttl=49 time=25.7 ms
^C
--- 72.30.35.9 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 25.704/25.724/25.745/0.161 ms
This indicates from server X, I can somehow connecting to outside/internet
user@reporter:/etc/network$ ping 8.8.8.8 -------------Note: I try to ping Google IP, does not work
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
^C
--- 8.8.8.8 ping statistics ---
7 packets transmitted, 0 received, 100% packet loss, time 6040ms
user@reporter:/etc/network$ ping 8.8.4.4 -------------Note: I try to ping another Google IP, works. Don't know why
PING 8.8.4.4 (8.8.4.4) 56(84) bytes of data.
64 bytes from 8.8.4.4: icmp_seq=1 ttl=50 time=12.8 ms
64 bytes from 8.8.4.4: icmp_seq=2 ttl=50 time=12.7 ms
^C
--- 8.8.4.4 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 12.719/12.768/12.817/0.049 ms
HOWEVER I CANNOT PING BY DOMAIN NAME
user@reporter:/etc/network$ ping www.yahoo.com -------------Note: I try to ping Yahoo name, does not work. This is the problem
ping: unknown host www.yahoo.com
user@reporter:/etc/network$ ping www.google.com -------------Note: I try to ping Google name, does not work
ping: unknown host www.google.com
user@reporter:~/Documents/tony/temp$ wget www.yahoo.com -------------Note: this command supposed to be get a index.html file
--2019-05-23 20:29:51-- http://www.yahoo.com/
Resolving www.yahoo.com (www.yahoo.com)... failed: Temporary failure in name resolution.
wget: unable to resolve host address ‘www.yahoo.com’
user@reporter:~/Documents/tony/temp$ wget 8.8.4.4 -------------Note: did not get anything, but output indicating "Connecting"
--2019-05-23 20:30:21-- http://8.8.4.4/
Connecting to 8.8.4.4:80... ^C
I know/guess this is more server level question, rather than router level. Just hope if there's a slight possibility it's router setting problem, and also hope someone here may know both router and Ubuntu sys. admin (we're actually willing to pay desired expert to fix the issue and for future/potential problems).
Thanks a lot!
-txu
