Linux - Network Error
Linux - Network Error
[toc]
ping fail
/etc/resolv.conf gets regenerated on boot, prevent resolv.conf to be update at boot time,
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# resolv.conf
nameserver 10.0.2.3
nameserver 192.168.1.1
nameserver 8.8.8.8
nameserver 8.8.4.4
search localhost
# cat /etc/sysconfig/network-scripts/ifcfg-eth0
Change PEERDNS=yes to PEERDNS=no
ping LAN but no internet
do have a connection, but you cannot reach your DNS; you can diagnose this by
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ping -c1 8.8.4.4
can reach Google, then you have a connection, and you only need to update your DNS servers. Edit (as sudo) your /etc/resolv.conf file and add these two lines:
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nameserver 8.8.8.8 nameserver 8.8.4.4
and now you are good to go.
cannot ping Google, but you can ping your router, or any other pc in your LAN. In this case case, it is possible that you also have problem 1, so you will have to check for that, but first, you need to check your routing table. Print it with
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ip route show default // if reply, like this one: default via 192.168.11.1 dev wlan0 proto dhcp metric 600
(this is for my laptop). What is important is that the correct IP address of your router is shown exactly where mine (192.168.11.1) is shown. If an incorrect IP address is shown, or, worse, if the ip route show default command receives no reply, then your routing table has been corrupted. You may simply restore it by means of:
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sudo ip route del default (only if the wrong IP address appears) sudo ip route add default via IP.address.OfYour.Router
and now we may go step 1.
If you cannot ping any pc on your LAN, then there is another kind of problem, and more questions will need to be asked. But we’ll cross that bridge when we get there.
configure ip for Interface
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$ route -n
$ ip r
dhcp
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// Lease information on the host:
$ cat /var/lib/dhclient/dhclient.leases
// Lookup DHCP host:
$ sudo grep “DHCPOFFER” /var/log/message
// check DHCP client
$ ss -luntp | grep dhclinet
capture the DHCP package
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$ sudo dhclient -r
$ dhclient
static
- add ip
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// Add an entry for the 1.1.1.1 to use 10.0.1.10 as the gateway.
$ ip route ad 1.1.1.1 via 10.0.1.10 dev eth0
// static ip
$ nmcli connection modify interface01 ipv4.method manual ipv4.address 10.0.1.15/24 ipv4.gateway 192.168.51.2
// configure DNS
$ nmcli con mod interface01 ipv4.dns 192.168.51.1
$ nmcli con down interface01
$ nmcli con up interface01
// change it to DHCP
$ nmcli con mod interface01 ipv4.method auto ipv4.address "" ipv4.gateway "" ipv4.dns ""
- prohibit ip
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$ yum install bind-utils
$ host google.com
$ ip route add prohibit 1.1.1.1 // runtime
$ ip route flush 1.1.1.1
Multiple IPs on the Same Interface
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// show interface
$ nmcli c // connection
$ nmcli d // device
$ nmcli d show eth0
// add ip addresses:
$ nmcli con mod System\eth0 ipv4.method manual ipv4.addresses 10.0.1.10/24 ipv4.gateway 10.0.1.1 ipv4.dns 10.0.0.2 ipv4.dns-search ec2.internal
// add 2 additional addresses:
$ sudo nmcli c mod System\eth0 ipv4.addresses 10.0.1.15/24, 10.0.1.20/24
//check where things stand now, run:
$ nmcli c show System\eth0 | grep ipv4
$ nmcli con show System\eth0 | grep ipv4
// Restart Networking
$ sudo systemctl restart network
NIC Bond and Teamin
- for fault tolerant, redundant connection
- Bond
- Team
Bond
- create master bond
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$ nmcli con add type bond con-name bond0 ifname bond0 mode actice-backup ip4 192.168.51.170/24
- add bond-slave ```c $ nmcli con add type bond-slave ifname ens33 master bond0 $ nmcli con add type bond-slave ifname ens38 master bond0
$ nmcli con up bond $ nmcli con up bond-slave33 $ nmcli con up bond-slave38
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3. add gateway for master bond
```c
$ nmcli con mod bond0 ipv4.gateway 192.168.51.2
$ nmcli con down bond0
$ nmcli con up bond0
Team
- clear the interface
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$ nmcli con deletet Wired\connection\1
$ nmcli con deletet Wired\connection\2
- Configure the Team Interface
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$ yum install -y teamd
// example configure
$ cat /usr/share/doc/teamd-1.27/example_configs/activebackup_ethtool_3.conf
$ nmcli con add type team con-name Team0 ifname team0 team.config '{"runner":{"name":"activebackup"}, "link_watch":{"name"::ethtool}}'
// for roundrobin
$ nmcli con add type team con-name Team0 ifname team0
$ nmcli con mod Team0 ipve.address 10.0.1.15/24 ipve.gateway 10.0.1.1 ipv4.method namual
- Add Slave Interfaces
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$ nmcli con add type team-slave con-name slave1 ifname eth1 master team0
$ nmcli con add type team-slave con-name slave2 ifname eth2 master team0
$ nmcli con up slave1
$ nmcli con up slave2
$ nmcli con up Team0
$ teamdctl team0 State
network related
checked network with lshw
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sudo lshw -C network
*-network
description: Wireless interface
product: BCM4313 802.11bgn Wireless Network Adapter
vendor: Broadcom Corporation
physical id: 0
bus info: pci@0000:03:00.0
logical name: eth2
version: 01
serial: 08:3e:8e:a2:91:9f
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=wl0 driverversion=6.20.155.1 (r326264)
latency=0 multicast=yes wireless=IEEE 802.11abg
resources: irq:17 memory:f2d00000-f2d03fff
firewall
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~$ sudo ufw status
password:
status: inactive
~$ sudo ufw enable
//激活fw
~$ sudo ufw status
status: active
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