/etc/postfix/main.cf

mynetworks = 192.168.0.0/16, 127.0.0.0/8

127.0.0.0/8     localhost

192.168.0.0/16  local LAN

10.1.11.1       my PC

mynetworks = /etc/postfix/my_cidr_table

HASH file format:

10.9.8.7       OK

127.0.0.1      localhost

192.168.1.1    sai PC

mynetworks = hash:/etc/postfix/my_cidr_table

inet_interfaces = 192.168.1.1, 127.0.0.1

or

inet_interfaces = all

or

inet_interfaces = lan0

relayhost = [smtp.myisp.com]

/etc/postfix/sasl_passwd

smtp.myisp.com    ispuser:isppassword

Annai:/etc/postfix # chown root:root sasl_passwd

Annai:/etc/postfix # chmod 600 sasl_passwd

Annai:/etc/postfix # postmap sasl_passwd

smtp_sasl_auth_enable = yes

smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd

Annai:/etc/postfix # rcpostfix restart

Shutting down mail service (Postfix)                                 done

Starting mail service (Postfix)                                      done

iftop can also run in promiscous mode and listen for all traffic on the subnet and can also listen for traffic on specified networks. iftop can be run in custom modes like disabling DNS name lookups, converting ports to service names, displaying results in Bytes etc.

For a detailed list of options run iftop with a “-h” arguement as follows:

opensuse11:~ # iftop -h
iftop: display bandwidth usage on an interface by host

Synopsis: iftop -h | [-npbBP] [-i interface] [-f filter code] [-N net/mask]

-h                  display this message
-n                  don’t do hostname lookups
-N                  don’t convert port numbers to services
-p                  run in promiscuous mode (show traffic between other
hosts on the same network segment)
-b                  don’t display a bar graph of traffic
-B                  Display bandwidth in bytes
-i interface        listen on named interface
-f filter code      use filter code to select packets to count
(default: none, but only IP packets are counted)
-F net/mask         show traffic flows in/out of network
-P                  show ports as well as hosts
-m limit            sets the upper limit for the bandwidth scale
-c config file      specifies an alternative configuration file

iftop, version 0.17
copyright (c) 2002 Paul Warren <pdw@ex-parrot.com> and contributors

Install IFTOP in openSUSE

Click from the 1-click installer for your openSUSE build to download the YMP file and launch an autmatic installation process which should add the required repositories and download and install the required packages and dependencies.

openSUSE 11.1

openSUSE 11.0

openSUSE 10.3

There are also IFTOP 1-click installers for

SLES/SLED 10

SLES 9

Once the installation finishes succesfully, iftop should be installed under /usr/sbin

opensuse11:~ # which iftop
/usr/sbin/iftop

To have a quick preview of the bandwidth utilization, simply run “iftop” without any arguements:

opensuse11:~ # iftop

To run in a promiscous mode and listen for all traffic on the subnet, run with “-p” option

opensuse11:~ # iftop -p

As shown earlier, use “-h” arguement for all options.

Click here to visit the project home.

Supports MySQL, Postress, Oracle, MS SQL and runs on Windows and Linux

Import network definitions from routing tables

Import definitions from TAB delimited files and NMAP’s XML format

Multiple administrators with different access profiles (per group, allowing access per customer, per network etc.)

Define address space authority boundaries per group

Finding free address space across a range

Split and join networks to make them smaller and larger

Display overlapping address space between networks

search capabilities, audit logs and statistics

Keeping track of and sending SWIP/RIPE/APNIC registrar information

DNS administration (forward and reverse zones, import existing zones via zone transfer)

Template system to extend IPplan to contain site specific information like circuit data, host configuration data, asset information

Device configuration file management

Link addresses together via pointers – ideal for NAT

Triggers – every user event can call a user defined function – useful to execute backend DNS scripts

External poller – scan subnets for active addresses to gather usage statistics

IP address request system – allows users to request static IP addresses from the database

IPplan’s own internal authentication scheme or an external Apache compatible system including single sign on systems like SiteMinder

IPPlan API for customisation

Install IPplan in SuSE / openSUSE

The installation procedure listed below is done on openSUSE 11.1 but should work fine on SuSE Linux as well.

Pre-Requisites

There is not much of a surprise here. IPplan requires Apache2, PHP and a Database software. To go with the LAMP tradition, I choose MySQL than anyother database. So, lets get started with installing the pre-requisites:

opensuse11:~ # yast2 -i apache2 mysql php5 php5-mysql apache2-mod_php5 php-zlib

This should install Apache 2 webserver, MySQL Database server and PHP5.

The following optional packages can be installed for multi-lingual and snmp support

php5-snmp – To import routing tables and directly query devices

php5-gettext – Multi-Lingial support

To install

opensuse11:~ # yast2 -i php5-snmp php5-gettext

Now, we are good to get IPplan installed. Download the latest stable package for IPplan (version 4.91a at the time of writing) from here

Untar & Unzip IPPlan source

Once downloaded, unzip and untar the downloaded file which will create the ipplan directory

opensuse11:~ # tar -zxvf ipplan-4.91a.tar.gz

Move, the ipplan directory to the Apache webserver root (/srv/www/htdocs).

opensuse11:~ # mv ipplan /srv/www/htdocs/

Change the directory ownership / permissions as follows:

opensuse11:~ # chown -R root:www ipplan

opensuse11:~ # chmod -R 750 ipplan

Create the following directory and set the permissions to allow users upload files:

opensuse11:~ # mkdir /var/spool/ipplanuploads

opensuse11:~ # chown wwwrun:www /var/spool/ipplanuploads

opensuse11:~ # chmod 750 /var/spool/ipplanuploads

MySQL Database

Now, lets get the MySQL Database, user created and privileges set:

If you installed MySQL just now, it is important to set the root password before proceeding to implementing ipplan.

Launch MySQL database server for the 1st time

opensuse11:~ # rcmysql start

Set the passwords as follows:

opensuse11:~ # mysqladmin -u root -p ‘your password’

For more information on LAMP in SuSE/openSUSE, click here

Create the Database

Logon to MySQL and create database.

opensuse11:~ # mysql -u root -p

mysql>CREATE DATABASE ipplan;
Query OK, 1 row affected (0.00 sec)

Set Database password

mysql> USE DATABASE ipplan ;

mysql> SET PASSWORD = PASSWORD(‘enterpassword’) ;

Create user

mysql> GRANT CREATE,ALTER,SELECT,INSERT,UPDATE,DELETE on ipplan.* TO ipplan@localhost IDENTIFIED by ‘password’;

Config.php

While almost all the default settings can be accepted, the password you set above needs to be updated on the config.pho file. Edit the config.php file in the ipplan directory and look for the line

define(“DBF_PASSWORD”, ‘ipplan’);

and set the password here. Also, look for the line

define(“ADMINPASSWD”, ‘admin’);

and set the password as you wish. This is required to run the install script.

Now, start the webserver

opensuse11:~ # rcapache2 start

Browse to

http://localhost/ipplan/admin/install.php

Here, select your language, select “Install” in the install/upgrade listbox and “Run the SQL now” in the next box and click “GO”

This should do. Browse IPplan as follows:

http://localhost/ipplan/

As a first step, create a new admin user (may be a new name or the username “admin” itself) and set the password to re-authenticate yourself. This can be done from “Admin – Users – Create a New user” set the group as “Admin – All groups”

That should all do…You can now, create users, customers, IP subnets. As you can see the software is very extensive when it comes to IP management. Telcos would love it as you can creat/manage customers, AS etc.For more detailed HOWTOs and screenshots, click here

ntop shows the current network usage and displays list of hosts currently on the network and report IP and Fibre Channel (FC) traffic generated by the host. ntop supports TCP/UDP (HTTP/FTP,DNS,Telnet,SMTP etc),ICMP, ARP & RARP,IP/IPX,DLC, Decnet, Apple Talk, Netbios, FC (Control Traffic – SW2, GS3,ELS & SCSI)

Install ntop on openSUSE

To install ntop on openSUSE, click on one of the following 1-click installers based on the version of openSUSE operating system.

openSUSE 11.1

openSUSE 11.0

openSUSE 10.3

This should launch YaST package manager and add requried repositories, install the required package and dependencies for ntop. Accept the defaults and follow the onscreen instructions to complete the installation. Once the installation is successfully completed, ntop will be installed under /usr/bin/

saihari:~ #which ntop

/usr/bin/ntop

When you run ntop (as a root user) for the first time, run ntop from a terminal window, this should initialize ntop and will let you set the password for the default ntop admin user (admin). Enter the password twice. By default the web interface is accessible from

http://localhost:3000

or

http://<ipaddress>:3000

Login with the user “admin” and password you just set.

Later on, you can start/stop/restart ntop as follows:

saihari:~ # rcntop start

Starting service ntop                 done

saihari:~ # rcntop stop

Stopping service ntop                 done

Quick Start with ntop

As soon as you logon to the web interface, everything becomes fairly straight forward as most if not all data shown in simple host/IP or protocol based tables and/or with nice grpahs, piecharts or graphs generated using the RRD Tools.

For instance,

If you would want to generate nice RRD Tools based graphs then it is important that RRD Tool (should be installed by default in openSUSE) and its RRD Tool devel packages, else ntop will report the following error at startup and disable the RRD Plugin which means no RRD based graphs.

**ERROR** RRD: Disabled – unable to create base directory (err 13, /usr/local/var/ntop/rrd)

To install RRD Tool and its devel package quickly from a terminal window,

saihari:~ # yast2 -i rrdtool rrdtool-devel

RRD Tool generated Graphs

The plugin architecture makes it easy to allow enhanced features like

netFlow/sFlow support where ntop can be configured to be a flow probe or a collector

Last time packet seen for hosts

ICMP traffic data

Plugin Architecture

Simply, click on the plugin (Yes/No) link to toggle between enable & disable from the Plugins menu.

You can also dump traffic data from ntop web interface

Dump Traffic Data

ntop has always been and will be so for long as a must have opensource tool for any network or system admin in any sized network or even on your home network. Click here to visit the project homepage.

Protocols supported are IP, TCP, UDP, ICMP, IGMP, IGP, IGRP, OSPF, ARP, RARP and supports Loopback, Ethernet, FDDI, SLIP, Asynchronus PPP, Synchronus PPP over ISDN, ISDN with RAW IP & Cisco HDLC Encapsulation and Parallel line IP.
Highlighting Features

Includes TCP flag information, packet and byte counts, ICMP details, OSPF packet types.
General and detailed interface statistics showing IP, TCP, UDP, ICMP, non-IP and other IP packet counts, IP checksum errors, interface activity, packet size counts.
A TCP and UDP service monitor showing counts of incoming and outgoing packets for common TCP and UDP application ports
A LAN statistics module that discovers active hosts and shows statistics showing the data activity on them
TCP, UDP, and other protocol display filters, allowing you to view only traffic you’re interested in.
Support for logging
Supports Ethernet, FDDI, ISDN, SLIP, PPP, and loopback interface types.
Utilizes the built-in raw socket interface of the Linux kernel, allowing it to be used over a wide range of supported network cards.

Install IPTraf

To install IPTraf on your openSUSE, click one of the following 1-click installers based on your openSUSE version.

openSUSE 11.1 (iptraf-3.0.0-138.7)

openSUSE 11.0 (iptraf-3.0.0-114.1)

openSUSE 10.3 (iptraf-3.0.0-76)

This should download the YMP file and launch YaST to start the installation. Click Next on the Additional Repositories window and Next on Software to be installed window and finally Next on the installation proposal window. Click Finish when the software install successfully completes.

This should install iptraf under /usr/sbin/iptraf

linux-pa5r:~ # which iptraf
/usr/sbin/iptraf

To start the utility, simply run “iptraf” from a terminal window to launch the Network monitoring console. Press any key to get the menu items. You can see a list of possible monitoring options inlucing thr live IP traffix monitor, a detailed and a general interface statiustics, Statistical breakdowns and LAN station monitor.

Before, you start monitoring, select “configure” from the menu and enable the options you would consider useful like Reverse DNS Lookup, TCP Service Names. To turn ON the option or to get its submenu, simply press Enter. You are also presented with keyboard shortcuts the good old way at the bottom of the screen. Once done with the configuration, exit and choose your monitoring option.

The IP Traffic Monitor shows real-time IP Traffic on the selected interfaces.

While Interface statistics (general & detailed) shows the number of packets, differentiting IP and Non-IP traffic and total bytes/bits in and out of the interfaces choosen.

A nice breakdown of the packets based on its size or by the TCP or UDP ports is provided by the Statistical breakdown options.

You can also choose to view the LAN monitor with the ethernet address of the end devices, IP packets in/out and Bytes/bits in/out etc.

Overall, IPTraf a very nicely done efficient console based Network Monitoring utility. Click here to visit the project homepage.

While this procedure is written for openSUSE 11.1, it should just work fine for openSUSE 11.0, openSUSE 10.3 as well as the 1-click install supports these versions.

Check the install Wireless module to confirm it is one of the above listed Broadcom Wireless devices.

openSUSE11_1:~ # lspci|grep -i broad
0b:00.0 Network controller: Broadcom Corporation BCM4312 802.11b/g (rev 01)

Click this to download and automatically start YaST Package manager. Click Next on the installation Welcome screen and click “Customize” on the screen showing the Repository and the packages selected to install. Click Next on the repository selection and screen.

And finally, in the screen showing the list of packages selected to install, untick the drivers for custom Kernels like Kernel-pae, Kernel-trace & Kernel-xen (unless you use any of these Kernel versions than the default one).

This means you will untick the following:

Broadcom-wl-kmp-pae
Broadcom-wl-kmp-trace
Broadcom-wl-kmp-xen

and finally, click Next on the proposal screen. This will start adding the packman repository and download and install the required driver packages and required dependencies. Click Finish when the drivers have successfully installed on your openSUSE.

Now, insert the installed wireless module

openSUSE11_1:~ # modprobe wl

Now, confirm the Kernel module is loaded on your openSUSE

openSUSE11_1:~ # lsmod | grep wl
wl                   1080320  0
ieee80211_crypt         6476  2 ieee80211_crypt_tkip,wl

Confirm with the iwconfig command:

openSUSE11_1:~ # iwconfig
lo        no wireless extensions.

eth0      no wireless extensions.

pan0      no wireless extensions.

eth1      IEEE 802.11bg  ESSID:”"
Mode:Managed  Frequency:2.412 GHz  Access Point: Not-Associated
Bit Rate:54 Mb/s   Tx-Power:32 dBm
Retry min limit:7   RTS thr:off   Fragment thr:off
Power Managementmode:All packets received
Link Quality=5/5  Signal level=0 dBm  Noise level=0 dBm
Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
Tx excessive retries:0  Invalid misc:0   Missed beacon:0

You are now ready to go, you should already see your KNetworkManager adjusting itself to insert the wireless (eth1 in my laptop) into its list of active devices.

From KnetworkManager, click “New Connection” and select your wireless device (eth1) in my laptop, select your Wireless Network from the list of scanned networks (or manually enter the details if your Wireless network doesn’t broadcast), click next and enter your Encryption details and click Connect & Save. You should now be up and running with your Wireless.

openSUSE11_1:~ # iwconfig
lo        no wireless extensions.

eth0      no wireless extensions.

eth1      IEEE 802.11bg  ESSID:”SKY12345″
Mode:Managed  Frequency:2.437 GHz  Access Point: 00:11:42:F3:AA:6E
Bit Rate=54 Mb/s   Tx-Power:32 dBm
Retry min limit:7   RTS thr:off   Fragment thr:off
Power Managementmode:All packets received
Link Quality=5/5  Signal level=-29 dBm  Noise level=-89 dBm
Rx invalid nwid:0  Rx invalid crypt:14  Rx invalid frag:0
Tx excessive retries:0  Invalid misc:0   Missed beacon:0

pan0      no wireless extensions.

Darkstat uses a very low footprint and the memory, CPU usage. DarkStat runs in the background of many Cable/DSL routers and are used in pfSense, redWall opensource firewalls.

Features include

Traffic graphs, reports per host, shows ports for each host
Embedded web-server with deflate compression
Asynchronous reverse DNS resolution using a child process
Small, Portable, Single-threaded, Efficient and Uncomplicated

Install DarkStat

DarkStat can be installed using one of the following 1-click installs based on your openSUSE version.

openSUSE 11.0

openSUSE 10.3

This should download the YaST MetaPackage file (YMP) and launch the YaST Package manager for installation. Click next on the window showing the selected repositories and next again on the package selection window and finally click Next on the installation proposal window. This should add the required repositories (click import when prompted to import the GPG Keys) and install DarkStat and required dependencies. Click Finish when the installation is completed succesfully.

Once installed, dartstat executable is loaded under at /usr/sbin/darkstat

opensuse11:~ # which darkstat
/usr/sbin/darkstat

While you can run with a lot of customization like the protocols ports IP Addresses networks, a simple way to run would be to run with the interface to monitor traffic.

opensuse11:~ # /usr/sbin/darkstat -i wlan0

This starts and keeps sniffing in the background. By default, darkstat serves the graphs at http://localhost:667 or http://<IP address>:667.

To view the graphs, go to http://localhost:667 if browsing from the local pc or from http://192.168.0.3:667 (where the IP here is IP Address of my system where it runs)

The graphs autorefresh every seconds however this can be modified and/or turned off.

For more options

opensuse11:~  # darkstat
darkstat 3.0.711 (built with libpcap 2.4)

usage: darkstat [ -i interface ]
[ -r file ]
[ --pppoe ]
[ --verbose ]
[ --no-daemon ]
[ --no-promisc ]
[ --no-dns ]
[ -p port ]
[ -b bindaddr ]
[ -f filter ]
[ -l network/netmask ]
[ --chroot dir ]
[ --user username ]
[ --daylog filename ]
[ --import filename ]
[ --export filename ]
[ --pidfile filename ]
[ --hosts-max count ]
[ --hosts-keep count ]
[ --ports-max count ]
[ --ports-keep count ]
[ --highest-port port ]

Please refer to the darkstat(1) manual page for further
documentation and usage examples.

Also, get more details from a wonderful man page

opensuse11:~ # man darkstat

Click here to visit the project homepage

net.core.rmem_max

Sets the Maximum Socket Receive Buffer for all protocols

net.core.wmem_max

sets the Maximum Socket Send Buffer for all protocols

net.ipv4.tcp_rmem

Sets the Maximum Socket Receive Buffer for TCP Protocol (overides the defaults set by net.core.rmem_default)

net.ipv4.tcp_wmem

Sets the Maximum Socket Send Buffer for TCP Protocol (overides the defaults set by net.core.wmem_default)

net.ipv4.tcp_no_metrics_save

Enables/Disables the behaviour of cachek performance charecteristics connection. By default, Linux Kernel remembers connection performance and congestion charecteristics.

net.ipv4.tcp_reordering

Sometimes, packet reordering in a network can be interpreted as packet loss and hence increasing the value of this parameter should improve performance (default is “3″)

net.ipv4.tcp_congestion_control

You can set this to one of the manu available high speed congestion variants like “cubic” “hs-tcp” (default is “reno”)

Before we set the values, lets look at the current values.

The following displays a long list of current values set for the Kernel Paramters.

opensuse11:~ # sysctl -a

To view the values of interest here

opensuse11:~ # sysctl -a | egrep “rmem|wmem|tcp_congestion|reordering|metrics”| egrep -v “default|udp|lowmem”
net.ipv4.tcp_reordering = 3
net.ipv4.tcp_wmem = 4096        16384   4194304
net.ipv4.tcp_rmem = 4096        87380   4194304
net.ipv4.tcp_no_metrics_save = 0
net.ipv4.tcp_congestion_control = reno
net.core.wmem_max = 131071
net.core.rmem_max = 131071

We can set the values are as follows:

net.ipv4.tcp_reordering = 20
net.ipv4.tcp_wmem = 8192 87380 16777216
net.ipv4.tcp_rmem = 8192 87380 16777216
net.ipv4.tcp_no_metrics_save = 1
net.ipv4.tcp_congestion_control = cubic
net.core.wmem_max = 16777216
net.core.rmem_max = 16777216

To set the values to be set at boot time, we need to edit the file “/etc/sysctl.conf” and add the above lines. However, this will not take effect immediatly. To make the changes to take effect immediatly,

opensuse11:~ # sysctl -p /etc/sysctl.conf

Alternatively, you can set one parameter value at a time as follows:

opensuse11:~ # sysctl -w net.ipv4.tcp_reordering=20

opensuse11:~ # sysctl -w net.ipv4.tcp_wmem=”8192 87380 16777216″

opensuse11:~ # sysctl -w net.ipv4.tcp_rmem=”8192 87380 16777216″

opensuse11:~ # sysctl -w net.ipv4.tcp_no_metrics_save=1

opensuse11:~ # sysctl -w net.ipv4.tcp_congestion_control=cubic

opensuse11:~ # sysctl -w net.core.wmem_max=16777216

This should improve Network Performance on your SuSE or openSUSE Linux.

Features include

support for /proc/net/dev, netstat, getifaddr, sysctl, kstat for Network Monitoring

support for /proc/diskstats /proc/partitions, IOKit, devstat and libstatgrab for Disk I/O Monitoring

Support for unlimited number of Network interfaces/devices

Dynamic Addition and Deletion of interfaces/devices to the list

Whitelist and blacklist of interfaces/devices

Output formats of KB/s, Kb/s, packets, errors, average, max and total sum

Output in curses, plain console, CSV or HTML

Install bwm-ng

Bandwidth monitor NG can quickly be built from source. Download bwm-ng from here or from a terminal window as follows:

opensuse11:~ # wget http://www.gropp.org/bwm-ng/bwm-ng-0.6.tar.gz

Unzip & Untar bwm-ng

opensuse11:~ # tar -zxvf bwm-ng-0.6.tar.gz

Install GCC and Make utility

If you do not already have the GCC compiler and the make utility then install as follows. If already installed then you can skip this step.

opensuse11:~ # yast2 -i gcc make

Now, change directory to the newly created bwm-ng directory and run configure.

opensuse11:~ # cd bwm-ng-0.6

opensuse11:~/bwm-ng-0.6 # ./configure

Compile & Install

Now, compile and install bwm-ng as follows:

opensuse11:~/bwm-ng-0.6 # make && make install

This should install bwm-ng under /usr/local/bin/bwm-ng

opensuse11:~ # which bwm-ng
/usr/local/bin/bwm-ng

Run bwm-ng

To see the stats of all the interfaces (including Wireless interfaces) on the system simply run bwm-ng without any arguements. At anytime press <CTRL+C> to stop monitoring the stats.

opensuse11:~ # bwm-ng

To see stats on a specific interface,

opensuse11:~ # bwm-ng -I wlan0

To check Disk I/O stats,

opensuse11:~ # bwm-ng -i disk

For more options, run bwm-ng with “-h” arguement to show the options

opensuse:~/bwm-ng-0.6 # bwm-ng -h
Bandwidth Monitor NG (bwm-ng) v0.6
Copyright (C) 2004-2007 Volker Gropp <bwmng@gropp.org>
USAGE: bwm-ng [OPTION] … [CONFIGFILE]
displays current ethernet interfaces stats

Options:
-t, –timeout <msec>    displays stats every <msec> (1msec = 1/1000sec)
default: 500
-d, –dynamic [value]   show values dynamicly (Byte KB or MB)
-a, –allif [mode]      where mode is one of:
0=show only up (and selected) interfaces
1=show all up interfaces (default)
2=show all and down interfaces
-I, –interfaces <list> show only interfaces in <list> (comma seperated), or
if list is prefaced with % show all but interfaces
in list
-S, –sumhidden [value] count hidden interfaces for total
-A, –avglength <sec>   sets the span of average stats (Default 30s)
-D, –daemon [value]    fork into background and daemonize
-h, –help              displays this help
-V, –version           print version info

Input:
-i, –input <method>    input method, one of: proc netstat disk
-f, –procfile <file>   filename to read raw data from. (/proc/net/dev)
–diskstatsfile <file> filename to read diskstats (Linux 2.6+) from. (/proc/diskstats)
–partitionsfile <file> filename to read diskstats (Linux 2.4) from. (/proc/partitions)

Output:
-o, –output <method>   output method, one of:
plain, csv, html
-u, –unit <value>      unit to show. one of bytes, bits, packets, errors
-T, –type <value>      type of stats. one of rate, max, sum, avg
-C, –csvchar <char>    delimiter for csv
-F, –outfile <file>    output file for csv and html (default stdout)
-R, –htmlrefresh <num> meta refresh for html output
-H, –htmlheader        show <html> and <meta> frame for html output
-c, –count <num>       number of query/output for plain & csv
-N, –ansiout           disable ansi codes for plain output
(ie 1 for one single output)

A simple but useful tool when trying to troubleshoot network problems or when there is a Disk I/O performance issue. Click here to visit the project homepage.

The MTU for ethernet is 1500 bytes, 1492 for PPPoE and 576 for Dialup. In very rare occasions, you may need to change the MTU size due to connectivity issues with your ISPs or in a VPN environment on your openSUSE.

The following procedure should help to change the Maximum Transmission Unit (MTU) in openSUSE.

In Network Manager

If you are using Network-Manager to control the network settings in your openSUSE then

1. From the menu, click Computer – YaST.

2. Click Network Devices in the leftpane and click Network Settings

3. Select the Network Adapter and click Edit.

4. Under General tab, select from the default “MTU” values or enter your own required value. Please be aware of what you are doing as an incorrect MTU size setting can cause connectivity and performance issues. Click Next and Finish to complete the settings wizard.

This will set the MTU value and restart the Network Service.

In traditional Network configuration

If you are not using the Network Manager and use the traditional method of controlling network settings using ifcfg scripts then

1. Using a terminal window, change directory to /etc/sysconfig/network/

opensuse:~ # cd /etc/sysconfig/network

2. In /etc/sysconfig/network directory, you have a config file for each of your network interface card. For instance, on my laptop, I have ifcfg-eth0 (ethernet) and ifcfg-wlan0 (wireless). These hold configurations for the respective network cards. Edit the interface file and enter the line as following

opensuse:/etc/sysconfig/network # vi ifcfg-eth0

and add a line like

MTU=’1460′

So it looks something like this

opensuse11:/etc/sysconfig/network # cat ifcfg-eth0
BOOTPROTO=’dhcp’
BROADCAST=”
ETHTOOL_OPTIONS=”
IPADDR=”
MTU=’1460′
NAME=’BCM4401-B0 100Base-TX’
NETMASK=”
NETWORK=”
REMOTE_IPADDR=”
STARTMODE=’auto’
USERCONTROL=’no’

3. Restart the network service or reboot your computer for the changes to take effect.

opensuse11:/etc/sysconfig/network # /etc/init.d/network restart

Dynamically change MTU

To dynamically change the MTU, you can use the ifconfig command. To change the MTU of interface eth0,

opensuse11:~ # ifconfig eth0 mtu 1460

However, this will be lost upon reboot.