POSTFIX Error “fatal: parameter inet_interfaces: no local interface found for ::1”

Issue

You are note able to restart / start postfix and getting the below error.
fatal: parameter inet_interfaces: no local interface found for ::1

Solution

Edit the file /etc/postfix/main.cf

vim /etc/postfix/main.cf

search for the line inet_interfaces = all

And change it to:

inet_interfaces = 127.0.0.1, 10.10.11.12 10.10.11.12 is your local IP address

:wq! Save and exit

restart postfix.

service postfix restart

Please Comment and share if this post was able to fix your issue

Original Article: fatal: parameter inet_interfaces: no local interface found for ::1

Configure IPTABLES to Allow Access to Common Services This article gives the steps to open firewall ports on CentOS in Iptables IPv4

Basics

  • Iptables rules can be changed on the fly by using the iptables binary.
  • The rules that are set using iptables command are in memory only and will vanish when the daemon is restarted.
  • The firewall rules added on the fly can be saved to the configuration file easily in CentOS/RHEL with the command service iptables save
    • This is no need to edit the configuration file unless you really want to.
  • The following examples are aimed at hardening the inbound traffic, but allowing all outbound traffic.
    • You can completely lock down all inbound, outbound and forwarded traffic if needed. It generally just causes a lot more administration and usually isn’t necessary.

Basic Commands

iptables –flush delete all firewall rules from memory.
iptables –list List current firewall policies
service iptables save (CentOS/RHEL) save current rules in memory to configuration file (/etc/sysconfig/iptables)
service iptables restart restart iptables daemon and load firewall rules from configuration file.
iptables-save > /root/firwallrules.fw save firewall rules in memory to a specific configuration file.
iptables-restore > /root/firwallrules.fw restore firewall rules from a specific configuration file to memory.

Basic iptables Command Parameters

  • -A append to policy chain
  • INPUT | OUTPUT | FORWARD policy chain identifiers
  • -p protocol
  • -m match
  • -s source
  • –dport destination port
  • –state connection state
  • -j jump target ACCEPT | DROP

Backup Current Iptables Configuration to File

Before you begin, it is recommended to backup your current firewall rules.

iptables-save > /path/to/somewhere/filename

Example:

iptables-save > /home/user1/iptable-rules-20130308.fw

Remove All Current Rules

iptables --flush

Set Policy Chains Default Rule

iptables -P INPUT DROP
 iptables -P OUTPUT ACCEPT
 iptables -P FORWARD ACCEPT

Allow Loopback

iptables -A INPUT -i lo -j ACCEPT

Allow All Established and Related Connections

iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

Allow ICMP “ping” from LAN (TCP Port 22)

iptables -A INPUT -p icmp -m icmp -s 192.168.0.0/24 --icmp-type echo-request -j ACCEPT

Allow SSH from LAN (TCP Port 22)

iptables -A INPUT -p tcp -m tcp -s 192.168.0.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT

Allow RSYNC from LAN (TCP Port 873)

iptables -A INPUT -p tcp -m tcp -s 192.168.0.0/24 --dport 873 -m state --state NEW,ESTABLISHED -j ACCEPT

Allow HTTP (TCP Port 80)

iptables -A INPUT -p tcp -m tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT

Allow HTTPS (TCP Port 443)

iptables -A INPUT -p tcp -m tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT

Allow MySQL Server Access from LAN (TCP Port 3306)

iptables -A INPUT -p tcp -m tcp -s 192.168.0.0/24 --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT

Allow Nagios NRPE Client Access from Nagios Server (TCP Port 5666)

iptables -A INPUT -s 192.168.0.100 -p tcp -m tcp --dport 5666 -m state --state NEW,ESTABLISHED -j ACCEPT

Save Current Rules in Memory to Configuration File

service iptables save

Restart Service

service iptables restart

iptables: insert a rule at a specific line number

# list the rules with line numbers

iptables -nL --line-numbers

# insert a rule at line 5

iptables -I INPUT 5 -p tcp -m state --state NEW -m tcp --dport 4000 -j ACCEPT

Related Articles: Configure iptablesiptables: insert a rule at a specific line number

How to disable IPv6 on Linux CentOS or RHEL 7 This Article describes procedure to disable IPv6 on CentOS or Red Hat 7.x

There are 2 ways to do this:

  1. Disable IPv6 in kernel module (requires reboot)
  2. Disable IPv6 using sysctl settings (no reboot required)

To verify if IPv6 is enabled or not, execute :

# ifconfig -a | grep inet6

inet6 fe80::211:aff:fe6a:9de4 prefixlen 64 scopeid 0x20
inet6 ::1 prefixlen 128 scopeid 0x10[host]

Disable IPv6 in kernel module (requires reboot)

1) Edit /etc/default/grub and add ipv6.disable=1 in line

GRUB_CMDLINE_LINUX, e.g.:

# vi /etc/default/grub

GRUB_TIMEOUT=5
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT=”console”
GRUB_CMDLINE_LINUX=”ipv6.disable=1 crashkernel=auto rhgb quiet”
GRUB_DISABLE_RECOVERY=”true”

2) Regenerate a GRUB configuration file and overwrite existing one:

# grub2-mkconfig -o /boot/grub2/grub.cfg

3) Restart system and verify no line “inet6” in “ip addr show” command output.

# shutdown -r now
 

# ip addr show | grep net6

Disable IPv6 using sysctl settings (no reboot required)

1) Append below lines in /etc/sysctl.conf:

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

NOTE : To disable IPv6 on a single interface add below lines to /etc/sysctl.conf :
net.ipv6.conf.[interface].disable_ipv6 = 1 ### put interface name here [interface]
net.ipv6.conf.default.disable_ipv6 = 1

2) To make the settings affective, execute :

# sysctl -p

NOTE : make sure the file /etc/ssh/sshd_config contains the line AddressFamily inet to avoid breaking SSH Xforwarding if you are using the sysctl method

3) Add the AddressFamily line to sshd_config :

# vi /etc/ssh/sshd_config
 ....
 AddressFamily inet
 ....
 Restart sshd for changes to get get effect :

# systemctl restart sshd

Related Articles: CentOS / RHEL 7 : How to disable IPv6

Initial Network Setup with UBUNTU Server Main steps to configure newtwork services on Linux Ubuntu Server

How do I change the hostname without a restart?

sudo hostname your-new-name

Assigning a static IP to Ubuntu Server

vi /etc/network/interfaces

Example:

auto eth0
 iface eth0 inet static

address 192.168.1.128
 netmask 255.255.255.0
 network 192.168.1.0
 broadcast 192.168.1.255
 gateway 192.168.1.1

How to disable IPv6 in Ubuntu?

vi /etc/sysctl.conf

insert the following lines at the end:

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

Linux Proxy Server Settings – Set Proxy For Command Line

env | grep -i proxy

check the file :

cat /etc/apt/apt.conf
cat /etc/environment

To Modify contents of file (remove everything from apt.conf for no proxy and only proxy sentences from environment)!

sudo nano /etc/apt/apt.conf
sudo nano /etc/environment
Acquire::http::Proxy "http://proxy.site.com:8080";

Manually edit DNS in Ubuntu

sudo nano /etc/resolvconf/resolv.conf.d/base

Add your DNS to the file :

nameserver 8.8.8.8
nameserver 8.8.4.4

Update resolv configuration:

sudo resolvconf -u

Setting up NTP on Ubuntu

sudo apt-get install ntp ntpdate

sudo nano /etc/ntp.conf

server myserverdnsname1 or IP
server myserverdnsname2 or IP
server myserverdnsname3 or IP

sudo service ntp start

sudo ntpd -gq

watch ntpq -cpe -cas

Grab you Ubuntu server HERE

How to Find MAC Addresse of NIC in Windows Team This article describes how to get the MAC addresses of all member Network Interface Cards (NICs)

There are lot of instances where the network communications fail when we are teaming up the incorrect network interfaces. Especially when the team members are the partitions of a virtual partition capable Converged Network Adapter (CNA), we need to make sure that we are teaming up correct partitions from different physical ports for redundancy and proper VLAN traffic. In such situations, the primary troubleshooting step related to network team’s connectivity issue is to validate the network team members.

The easiest way to ensure this is to compare the unique attributes of the partitioned interfaces with the data in the network card BIOS or out-of-band management tools (like iDRAC, ILO etc) or other baseboard management controllers. Media Access Control (MAC) addresses of the partitioned interfaces seen by the Operating System are the easiest and reliable unique identifiers in this scenario as the names for the interfaces will be different for different network cards.

The default available option to get the member NIC’s MAC address is to use the PowerShell command Get-NetAdapter <member NIC name>. For that we have to manually find the native teams in the server, their member NICs and then the MAC addresses of the member NICs.

The following short PowerShell script will automate this process and will list down the MAC addresses of the member NICs of all the native windows teams available in the server. The advantage with the below script is that it can be used on any Windows 2012 or Windows 2012 R2 servers without any modifications/inputs.

Script:

foreach ($i in ((Get-NetLbfoTeam).name))
{
Write-Host “`nTeam Name – “$i`n”Team Members: ”
Get-NetAdapter (Get-NetLbfoTeamMember -Team $i).Name | Format-Table
}

The best way is to open notepad, copy and paste this script, then save the file as ‘Save As’ > Select ‘All files’ > then name the file ‘nic.ps1’ > destination > where you want

Open Powershell, and run the file .ps1 from it:

MAC_Addresses_NIC_Team_2012
MAC_Addresses_NIC_Team_2012

Related Article: Technet Microsoft