Not able to connect to the internet after configuring a static ip in centos 7

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iAnathema
Posts: 5
Joined: 2017/12/28 17:16:05

Not able to connect to the internet after configuring a static ip in centos 7

Post by iAnathema » 2017/12/28 17:24:51

I have the same problem!!!

If I switch to dhcp, all works correctly again.

My network-script:

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DEVICE=enp1s0
BOOTPROTO=static
NM_CONTROLLED="no"
#PERSISTENT_DHCLIENT=1
ONBOOT="yes"
TYPE=Ethernet
DEFROUTE=yes
PEERDNS=yes
PEERROUTES=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPV6_FAILURE_FATAL=no
NAME="eth0"

IPADDR=172.20.0.25
NETMASK=255.255.255.0
GATEWAY=172.20.0.1
DNS1 = 8.8.8.8
DNS2 = 8.8.4.4

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[root@server ~]# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         172.20.0.1      0.0.0.0         UG        0 0          0 enp1s0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 enp1s0
172.20.0.0      0.0.0.0         255.255.255.0   U         0 0          0 enp1s0
[root@server ~]#

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[root@server ~]# cat /etc/resolv.conf
nameserver 8.8.8.8
nameserver 8.8.8.4
[root@server ~]#
Gateway Ping Stuck

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[root@server ~]# ping 172.20.0.1
PING 172.20.0.1 (172.20.0.1) 56(84) bytes of data.
^C
--- 172.20.0.1 ping statistics ---
13 packets transmitted, 0 received, 100% packet loss, time 11999ms

[root@server ~]#

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TrevorH
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Re: Not able to connect to the internet after configuring a static ip in centos 7

Post by TrevorH » 2017/12/28 22:45:09

When you use DHCP, do you get assigned an ip address that's within 172.20.0.0/24?
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iAnathema
Posts: 5
Joined: 2017/12/28 17:16:05

Re: Not able to connect to the internet after configuring a static ip in centos 7

Post by iAnathema » 2017/12/29 08:29:25

Yep...

For Example :

Dhcp give me the address 172.20.0.30 it's works.
After this if I set the static address 172.20.0.25....it doesn't work...
Then if I set the same static address that the Dhcp server gave to me(172.20.0.30), it's works!

Another stranger thing... If i ping from another host the static address, the ping work, but backwards I can't ping no host from my CentOS server in my network except localhost and itself

I'm going mad!

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TrevorH
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Re: Not able to connect to the internet after configuring a static ip in centos 7

Post by TrevorH » 2017/12/29 10:35:25

Post the output from ip route show from both DHCP (working) and non-working static setups.
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iAnathema
Posts: 5
Joined: 2017/12/28 17:16:05

Re: Not able to connect to the internet after configuring a static ip in centos 7

Post by iAnathema » 2017/12/29 10:45:26

DHCP

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[root@localhost ~]# ifconfig
enp1s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.20.0.30  netmask 255.255.255.0  broadcast 172.20.0.255
        inet6 fe80::7ed3:aff:fe2e:4d8e  prefixlen 64  scopeid 0x20<link>
        ether 7c:d3:0a:2e:4d:8e  txqueuelen 1000  (Ethernet)
        RX packets 2493  bytes 299246 (292.2 KiB)
        RX errors 0  dropped 64  overruns 0  frame 0
        TX packets 5178  bytes 5238082 (4.9 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 808  bytes 419820 (409.9 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 808  bytes 419820 (409.9 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        
[root@localhost ~]# ip route show
default via 172.20.0.1 dev enp1s0
169.254.0.0/16 dev enp1s0 scope link metric 1002
172.20.0.0/24 dev enp1s0 proto kernel scope link src 172.20.0.30
[root@localhost ~]# ping 172.20.0.1
PING 172.20.0.1 (172.20.0.1) 56(84) bytes of data.
64 bytes from 172.20.0.1: icmp_seq=1 ttl=64 time=0.280 ms
64 bytes from 172.20.0.1: icmp_seq=2 ttl=64 time=0.250 ms
64 bytes from 172.20.0.1: icmp_seq=3 ttl=64 time=0.249 ms
64 bytes from 172.20.0.1: icmp_seq=4 ttl=64 time=0.242 ms
64 bytes from 172.20.0.1: icmp_seq=5 ttl=64 time=0.422 ms
64 bytes from 172.20.0.1: icmp_seq=6 ttl=64 time=0.285 ms
64 bytes from 172.20.0.1: icmp_seq=7 ttl=64 time=0.284 ms
^C
--- 172.20.0.1 ping statistics ---
7 packets transmitted, 7 received, 0% packet loss, time 6000ms
rtt min/avg/max/mdev = 0.242/0.287/0.422/0.059 ms
[root@localhost ~]#
Static IP

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[root@localhost ~]# ifconfig
enp1s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.20.0.25  netmask 255.255.255.0  broadcast 172.20.0.255
        inet6 fe80::7ed3:aff:fe2e:4d8e  prefixlen 64  scopeid 0x20<link>
        ether 7c:d3:0a:2e:4d:8e  txqueuelen 1000  (Ethernet)
        RX packets 1168  bytes 136294 (133.0 KiB)
        RX errors 0  dropped 32  overruns 0  frame 0
        TX packets 2344  bytes 2292480 (2.1 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 293  bytes 173948 (169.8 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 293  bytes 173948 (169.8 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root@localhost ~]# ip route show
default via 172.20.0.1 dev enp1s0
169.254.0.0/16 dev enp1s0 scope link metric 1002
172.20.0.0/24 dev enp1s0 proto kernel scope link src 172.20.0.25
[root@localhost ~]# ping 172.20.0.1
PING 172.20.0.1 (172.20.0.1) 56(84) bytes of data.
Ping stuck!

iAnathema
Posts: 5
Joined: 2017/12/28 17:16:05

Re: Not able to connect to the internet after configuring a static ip in centos 7

Post by iAnathema » 2017/12/29 11:03:37

Another clue.

If i ping from server an inexistent address it resposes: "Destination Host Unreachable",
while if it exists the ping stuck

pjsr2
Posts: 343
Joined: 2014/03/27 20:11:07

Re: Not able to connect to the internet after configuring a static ip in centos 7

Post by pjsr2 » 2017/12/29 12:20:36

Dhcp give me the address 172.20.0.30 it's works.
After this if I set the static address 172.20.0.25....it doesn't work...
Then if I set the same static address that the Dhcp server gave to me(172.20.0.30), it's works!
Do you have a router/switch between your computer and the gateway (172.20.0.1) that restricts network traffic to only traffic originating from the IP address range that is provided by the DHCP server?

iAnathema
Posts: 5
Joined: 2017/12/28 17:16:05

Re: Not able to connect to the internet after configuring a static ip in centos 7

Post by iAnathema » 2017/12/29 13:06:05

Yep, but i tried to make a connect Host2Host with my notebook ad result was the same

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TrevorH
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Re: Not able to connect to the internet after configuring a static ip in centos 7

Post by TrevorH » 2017/12/29 16:13:07

What pool is your DHCP server set up to hand out? Perhaps you need to pick a static ip from outside of the range it believes belongs to it to assign.
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