Cannot ping to localhost into CentOS

Question

I'm connecting to my server (Centos 7) with ssh and I try to ping to localhost: ping 127.0.0.1 but doesn't work:

ping 127.0.0.1

PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
^C
--- 127.0.0.1 ping statistics ---
78 packets transmitted, 0 received, 100% packet loss, time 76999ms

Here my files. networks:

default 0.0.0.0
loopback 127.0.0.0
link-local 169.254.0.0

hosts:

# nameserver config
# IPv4
127.0.0.1 localhost.localdomain localhost
1xx.xxx.xxx.xxx  server
#
# IPv6
::1     ip6-localhost ip6-loopback
...

lo route:

DEVICE=lo
IPADDR=127.0.0.1
NETMASK=255.0.0.0
NETWORK=127.0.0.0
# If you're having problems with gated making 127.0.0.0/8 a martian,
# you can change this to something else (255.255.255.255, for example)
BROADCAST=127.255.255.255
ONBOOT=yes
NAME=loopback

I need make a ping! What I can do?

Solution

After checking that local interface is up (ifup lo0 or similar).

Check for routes, firewall or iptables problem.

Here it was a problem from the file located here /proc/sys/net/ipv4/icmp_echo_ignore_all
When set to 1 : There is no response to ICMP Requests, so ping will not work.
When set to 0 : Replies to ICMP Requests are enable.

Check if sets to 1. If so, set it to 0 by using this command : echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_all

Now, your machine replies to ping.

Comments

[Nico]

maybe bring up local interface : ifup lo ?

[Neil]

Is currently UP :/

[Nico]

Check routes, firewall, iptables ? Do you have a resolv.conf ? If no, please create one for testing purpose at least

[Nico]

Also check if /proc/sys/net/ipv4/icmp_echo_ignore_all is set to 0 if it exists.

[Neil]

iptables and firewall are disabled. I have a resolv.conf file. Lets to check routes.

[Neil]

Is set to 1? What I have to do?

[Neil]

I've added the lo route file into question.

[Nico]

try setting it to 0 with echo 0 > path_to_file. Guess its the cause

[Neil]

Like this: echo "0" > /proc/sys/net/ipv4/icmp_echo_ignore_all IT WORKS! Thanks!

[Neil]

And for set this permanently? @Nico you are the best!

[Nico]

No problem. This file is saying : Should I answer to ICMP Requests ? with 0 you answer : "Do not ignore all", if sets to 1 you say "Yes, ignore everything". Hope I'm clear enough. Next time, try a google research first with "centos cannot ping 127.0.0.1" with the 5 first links, you should be able to solve and understand the problem ;) You can answer your own question, or I can do it if you prefer

[Ryan Pendleton]

Did you accidently switch 0 and 1 in the first part of your answer?