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Showing posts with label Linux Networking. Show all posts
Showing posts with label Linux Networking. Show all posts

Sunday, December 9, 2018

How to setup and configure Network Teaming on RHEL 7 server

Sunday, December 09, 2018 0
Here we are using nmcli to configure the network teaming. 

 nmtui : Text user Interface
nmcli : Command line Interface
Teaming type : loadbalance
Interface         : team0, eth0, eth2

 teamd package should be installed on server.

 We can see the previous network configuration setup by using nmcli command.

 root@nsk# nmcli con show
NAME  UUID                                                            TYPE      DEVICE
eth0     5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03     ethernet    eth0
eth1     8761e75a-0ba3-4f73-80e4-66df47023ed1  ethernet    eth1

 Teaming configuration

 Execute the below command on server to create team0 teaming interface.

 root@nsk# nmcli con add type team con-name team0 ifname team0 config '{ "runner": {"name": "loadbalance"}}'
Connection 'team0' (e07596d2-59b6-406a-a742-07d5ff96901b) successfully added.

root@nsk# nmcli con show
NAME   UUID                                                              TYPE      DEVICE
eth0     5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03        ethernet    eth0
eth1     8761e75a-0ba3-4f73-80e4-66df47023ed1     ethernet    eth1
team0  e07596d2-59b6-406a-a742-07d5ff96901b     team         team0

 Now, /etc/sysconfig/network-scripts/team0 contains below lines

 root@nsk# cat ifcfg-team0
TEAM_CONFIG="{\"runner\": {\"name\": \"loadbalance\", \"tx_hash\": [\"eth\", \"ipv4\", \"ipv6\"]}}"
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=dhcp
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=team0
UUID=e07596d2-59b6-406a-a742-07d5ff96901b
DEVICE=team0
ONBOOT=yes
DEVICETYPE=Team

 Now add IPv4 address on team0 interface.

 root@nsk# nmcli con mod team0 ipv4.addresses 172.27.0.169/28
root@nsk# nmcli con mod team0 ipv4.gateway 172.27.0.161
root@nsk# nmcli con mod team0 ipv4.method manual

 Add eth0 interface to the teaming interface.

 root@nsk# nmcli con add type team-slave con-name team0-slave0 ifname eth0 master team0
Connection 'team0-slave0' (5fa33d1b-3f25-4fda-b10d-a184e4260cbe) successfully added.

 Add eth2 interface to the teaming interface.

 root@nsk# nmcli con add type team-slave con-name team0-slave1 ifname eth2 master team0
Connection 'team0-slave1' (bbdb784b-2a9c-4fe3-9a19-11d64a9748ff) successfully added.

 root@nsk# ls -al | grep -i team0

 ifcfg-team0  
ifcfg-team0-slave0  
ifcfg-team0-slave1

 Now bring up the team0 interface.

 root@nsk# nmcli connection up team0
Connection successfully activated (master waiting for slaves) (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/11)

 root@nsk# teamdctl team0 state
setup:
  runner: loadbalance

 root@nsk# /etc/init.d/network restart
Restarting network (via systemctl):                        [  OK  ]

 root@nsk# ifconfig | egrep -i "eth0|eth2|team0"

 eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        ether b0:83:fe:d8:44:02  txqueuelen 1000  (Ethernet)
        RX packets 2930895882  bytes 2216873481505 (2.0 TiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1694125755  bytes 312320131645 (290.8 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 56

 eth2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        ether b0:83:fe:d8:44:02  txqueuelen 1000  (Ethernet)
        RX packets 2705861  bytes 301266106 (287.3 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 25  bytes 4159 (4.0 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 59

 team0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.27.0.169  netmask 255.255.255.240  broadcast 172.27.0.175
        inet6 fe80::bbe8:90aa:4108:e728  prefixlen 64  scopeid 0x20<link>
        ether b0:83:fe:d8:44:02  txqueuelen 1000  (Ethernet)
        RX packets 35  bytes 2586 (2.5 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 28  bytes 4451 (4.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

 Check the configuration

 root@nsk# nmcli con reload
root@nsk# nmcli con show
NAME                 UUID                                                             TYPE      DEVICE
eth1                    8761e75a-0ba3-4f73-80e4-66df47023ed1   ethernet    eth1
team0                 e07596d2-59b6-406a-a742-07d5ff96901b   team         team0
team0-slave0     5fa33d1b-3f25-4fda-b10d-a184e4260cbe     ethernet    eth0
team0-slave1     bbdb784b-2a9c-4fe3-9a19-11d64a9748ff     ethernet    eth2

 Check the team0 ports status

 root@nsk# teamnl team0 ports
 4: eth2: up 1000Mbit FD
 2: eth0: up 1000Mbit FD

 We can use teamdctl command to check team0 configuration status.

 root@nsk# teamdctl team0 state
setup:
  runner: loadbalance
ports:
  eth0
    link watches:
      link summary: up
      instance[link_watch_0]:
        name: ethtool
        link: up
        down count: 0
  eth2
    link watches:
      link summary: up
      instance[link_watch_0]:
        name: ethtool
        link: up
        down count: 0
root@nsk#

 Note : If we need Activebackup setup, just replace the loadbalance with activebackup while creating team0 interface.
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Tuesday, November 7, 2017

How to check the Listening Ports on Linux Server - Linvirtshell

Tuesday, November 07, 2017

We can check the listening ports on Linux Server by below ways

fuser - identify processes using files or sockets (Refer- Man Pages for more information)

Linvirtshell.com

netstat -  Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships (Refer- Man Pages for more information)

Linvirtshell.com

ssh  - OpenSSH SSH client (remote login program)  (Refer- Man Pages for more information)

[root@nsk-linux ~]# ssh -vv 10.0.2.15 25

OpenSSH_5.3p1, OpenSSL 1.0.1e-fips 11 Feb 2013
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to 10.0.2.15 [10.0.2.15] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/identity-cert type -1
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_rsa-cert type -1
....
...

lsof - list open files (Refer- Man Pages for more information)

Linvirtshell.com

  nmap - Network exploration tool and security / port scanner (Refer- Man Pages for more information) 

Here for ex, i took output from localhost, you can change any ip or server name.
Linvirtshell.com

telnet -  user interface to the TELNET protocol  (Refer- Man Pages for more information)

Here for ex, i took output from localhost, you can change any ip or server name.

Linvirtshell.com
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Thursday, September 14, 2017

How tcpdump command is used to find out the network switch information which is connected to the physical server?

Thursday, September 14, 2017 0
Run the below tcpdump command on physical server.

 [root@testserver001 ~]# tcpdump -nn -v -i eth0 -s 1500 -c 1 'ether[20:2] == 0x2000'
tcpdump: WARNING: eth0: no IPv4 address assigned
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 1500 bytes
05:51:39.526913 CDPv2, ttl: 180s, checksum: 692 (unverified), length 434
        Device-ID (0x01), length: 21 bytes: 'TEST01.switch.com'
        Version String (0x05), length: 295 bytes:
          Cisco Internetwork Operating System Software
          IOS (tm) s72033_rp Software (s72033_rp-ADVIPSERVICESK9_WAN-M), Version 12.2(18)SXF17a, RELEASE SOFTWARE (fc1)
          Technical Support: http://www.cisco.com/techsupport
          Copyright (c) 1986-2010 by cisco Systems, Inc.
          Compiled Tue 02-Mar-10 01:50 by tinhuang
        Platform (0x06), length: 16 bytes: 'cisco WS-C6506-E'
        Address (0x02), length: 13 bytes: IPv4 (1) 159.166.128.131
        Port-ID (0x03), length: 16 bytes: 'FastEthernet3/12'
        Capability (0x04), length: 4 bytes: (0x00000029): Router, L2 Switch, IGMP snooping
        VTP Management Domain (0x09), length: 0 byte: ''
1 packets captured
3 packets received by filter
0 packets dropped by kernel
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Tuesday, June 14, 2016

How Traceroute Works?

Tuesday, June 14, 2016 0
Traceroute utility uses the TTL field in the IP header to achieve its operation. For users who are new to TTL field, this field describes how much hops a particular packet will take while traveling on network.

So, this effectively outlines the lifetime of the packet on network. This field is usually set to 32 or 64. Each time the packet is held on an intermediate router, it decreases the TTL value by 1. When a router finds the TTL value of 1 in a received packet then that packet is not forwarded but instead discarded.

After discarding the packet, router sends an ICMP error message of “Time exceeded” back to the source from where packet generated. The ICMP packet that is sent back contains the IP address of the router.

So now it can be easily understood that traceroute operates by sending packets with TTL value starting from 1 and then incrementing by one each time. Each time a router receives the packet, it checks the TTL field, if TTL field is 1 then it discards the packet and sends the ICMP error packet containing its IP address and this is what traceroute requires. So traceroute incrementally fetches the IP of all the routers  between the source and the destination.
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Thursday, December 3, 2015

What are the tools available to properly diagnose a network performance problem in Linux Server?

Thursday, December 03, 2015 0
Below listed Linux tools are used to diagnose the network performance in Linux server.

netstat

    A command-line utility that prints network connections, routing tables, interface statistics, masquerade connections and multicast memberships. It retrieves information about the networking subsystem from the /proc/net/ file system. These files include:

        /proc/net/dev (device information)
        /proc/net/tcp (TCP socket information)
        /proc/net/unix (Unix domain socket information)

    For more information about netstat and its referenced files from /proc/net/, refer to the netstat man page: man netstat.
dropwatch
    A monitoring utility that monitors packets dropped by the kernel. For more information, refer to the dropwatch man page: man dropwatch.

ip
    A utility for managing and monitoring routes, devices, policy routing, and tunnels.

ethtool
    A utility for displaying and changing NIC settings.

/proc/net/snmp
    A file that displays ASCII data needed for the IP, ICMP, TCP, and UDP management information bases for an snmp agent. It also displays real-time UDP-lite statistics.
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Monday, November 2, 2015

Difference Between RHEL 5, 6, AND 7 - NETWORKING

Monday, November 02, 2015 0
Difference Between RHEL 5, 6, AND 7 - NETWORKING

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Wednesday, October 14, 2015

Default route in Linux by command

Wednesday, October 14, 2015 0
By using below command we can add the default route -Temporarily.

#route add gw IP Address Netmask ethx up 

IP Address = Gateway IP Address of your network (ex 192.168.0.1)
Netmask = Your network mask (255.255.255.0)
ethx - Gateway Interface

# route add gw 192.168.0.1 255.255.255.0 eth1 up
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How to change the active ethernet interface on Bond configuration

Wednesday, October 14, 2015 0
By Using the below command we can change the active ethernet interface settings on Bond configuration

#ifenslave -c bondx ethx

ethx - which interface you want to make an active
bondx - which bond configuration
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Tuesday, September 15, 2015

RHEL: Linux Bonding / Teaming Multiple Network Interfaces (NIC) Into a Single Interface

Tuesday, September 15, 2015 0
Step #1: Create a Bond0 Configuration File

Red Hat Enterprise Linux (and CentOS) stores network configuration in /etc/sysconfig/network-scripts/ directory.
First, you need to create a bond0 config file as follows:

# vi /etc/sysconfig/network-scripts/ifcfg-bond0

Append the following linest:
DEVICE=bond0
IPADDR=192.168.1.20
NETWORK=192.168.1.0
NETMASK=255.255.255.0
USERCTL=no
BOOTPROTO=none
ONBOOT=yes

Replace IP address with your actual setup. Save and close the file.

Step #2: Modify eth0 and eth1 config files Open both configuration using a text editor such as vi/vim, and make sure file read as follows for eth0 interface

# vi /etc/sysconfig/network-scripts/ifcfg-eth0

Modify/append directive as follows:
DEVICE=eth0
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none

Open eth1 configuration file using vi text editor, enter:

# vi /etc/sysconfig/network-scripts/ifcfg-eth1

Make sure file read as follows for eth1 interface:
DEVICE=eth1
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none

Save and close the file.

Step # 3: Load bond driver/module

Make sure bonding module is loaded when the channel-bonding interface (bond0) is brought up. Modify kernel modules configuration file:

# vi /etc/modprobe.conf

Append following two lines:
alias bond0 bonding
options bond0 mode=balance-alb miimon=100

 **********************************************************

Below are list of modes used in Network Bonding :

    balance-rr or 0 – round-robin mode for fault tolerance and load balancing.
    active-backup or 1 – Sets active-backup mode for fault tolerance.
    balance-xor or 2 – Sets an XOR (exclusive-or) mode for fault tolerance and load balancing.
    broadcast or 3 – Sets a broadcast mode for fault tolerance. All transmissions are sent on all slave interfaces.
    802.3ad or 4 – Sets an IEEE 802.3ad dynamic link aggregation mode. Creates aggregation groups that share the same
    speed & duplex settings.
    balance-tlb or 5 – Sets a Transmit Load Balancing (TLB) mode for fault tolerance & load balancing.
    balance-alb or 6 – Sets an Active Load Balancing (ALB) mode for fault tolerance & load balancing

************************************************************

Save file and exit to shell prompt. You can learn more about all bounding options by clicking here).

Step # 4: Test configuration

First, load the bonding module, enter:
# modprobe bonding

Restart the networking service in order to bring up bond0 interface, enter:
# service network restart

Make sure everything is working. Type the following cat command to query the current status of Linux kernel bounding driver, enter:

# cat /proc/net/bonding/bond0

Sample outputs:

Bonding Mode: load balancing (round-robin)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 200
Down Delay (ms): 200
Slave Interface: eth0
MII Status: up
Link Failure Count: 0
Permanent HW addr: 00:0c:29:c6:be:59
Slave Interface: eth1
MII Status: up
Link Failure Count: 0
Permanent HW addr: 00:0c:29:c6:be:63

To list all network interfaces, enter:
# ifconfig

Sample outputs:

bond0     Link encap:Ethernet  HWaddr 00:0C:29:C6:BE:59
 inet addr:192.168.1.20  Bcast:192.168.1.255  Mask:255.255.255.0
 inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
 UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1
 RX packets:2804 errors:0 dropped:0 overruns:0 frame:0
 TX packets:1879 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:0
 RX bytes:250825 (244.9 KiB)  TX bytes:244683 (238.9 KiB)
eth0      Link encap:Ethernet  HWaddr 00:0C:29:C6:BE:59
 inet addr:192.168.1.20  Bcast:192.168.1.255  Mask:255.255.255.0
 inet6 addr: fe80::20c:29ff:fec6:be59/64 Scope:Link
 UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1
 RX packets:2809 errors:0 dropped:0 overruns:0 frame:0
 TX packets:1390 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1000
 RX bytes:251161 (245.2 KiB)  TX bytes:180289 (176.0 KiB)
 Interrupt:11 Base address:0x1400
eth1      Link encap:Ethernet  HWaddr 00:0C:29:C6:BE:59
 inet addr:192.168.1.20  Bcast:192.168.1.255  Mask:255.255.255.0
 inet6 addr: fe80::20c:29ff:fec6:be59/64 Scope:Link
 UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1
 RX packets:4 errors:0 dropped:0 overruns:0 frame:0
 TX packets:502 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1000
 RX bytes:258 (258.0 b)  TX bytes:66516 (64.9 KiB)
 Interrupt:10 Base address:0x1480
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