Network Issues

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Revision as of 16:55, 7 January 2014 by Apos (talk | contribs) (→‎Montitor ip changes)

Own internet ip

curl -s http://www.ipchicken.com/ | awk '/[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ {print $1}' | uniq

Own local ip

all ip's: 

ifconfig | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1'

or for a particualar interface: 

ifconfig wlan0 | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1'

or: 

alias myip="ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p'"

Montitor ip changes

BIG script, inspired by some others ...

This script monitors a maximum of two simultanuisly connnections out of one of these

  • ppp0
  • wlan0
  • eth0

It reports changes on

  • name and ip of each interface
  • default router

It can be used to fine tune network issues. 


#!/bin/bash
export LC_MESSAGES="en_US.UTF-8"
export LC_TYPE="en_US.UTF-8"
export LANGUAGE="en_US.UTF-8"

IGNORE_DEV="virbr0|tun0"

WORKING_IP="/tmp/workingip.txt"
GOT_IP="/tmp/gotip.txt"
DEV_IP="/tmp/devip.txt"
ADEV="/tmp/adev.txt"
WORKING_DEV_IP="/tmp/wdevip.txt"
DEV_IP2="/tmp/devip2.txt"
ADEV2="/tmp/adev2.txt"
WORKING_DEV_IP2="/tmp/wdevip2.txt"
DEV="/tmp/dev.txt"
GW_DEV="/tmp/gwdev.txt"
WORKING_GW_DEV="/tmp/wgwdev.txt"

# When the gateway of the system changes, do ...
on_gw_change() {
	echo "gateyway changed."
}

# When the public internet address of the system changes, do ...
on_internet_adress_change() {
	echo "public ip changed."
}

# When the local address of your network card(s) changes
on_local_address_change() {
	echo "local ip address changed."
}


# watch -n2 "echo -n 'WRK:'; cat /tmp/workingip.txt ;echo -n 'GOT:';  cat /tmp/gotip.txt ; echo -n 'DIP:'; cat /tmp/devip.txt; echo -n 'ADEV:'; cat /tmp/adev.txt;  echo -n 'WDEV:'; cat /tmp/wdevip.txt; echo -n 'GWDEV:'; cat /tmp/gwdev.txt;  echo -n 'WGWDEV:'; cat /tmp/wgwdev.txt;"

# Initiate first
dig @ns1.google.com 2> /dev/null 1> /dev/null && myip="$(dig @ns1.google.com -t txt o-o.myaddr.l.google.com +short | sed s/\"/\/g)"
# myip=$(curl -s http://www.ipchicken.com/ | awk '/[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ {print $1}' | uniq | grep -v curl)

# requires stun: 
# apt-get install stun
# sudo service stun stop
# sudo update-rc.d -f stun remove
#myip=$(stun -v stunserver.org 2>&1 1>/dev/null | grep MappedAddress | sed -e 's/.*MappedAddress = //' -e 's/:.*//' | uniq)

echo ${myip} > ${GOT_IP}
cp ${GOT_IP} ${WORKING_IP}

ACTIVE_DEVICE_1="$(nmcli dev status | grep -v disconnected | grep connected | grep -v ${IGNORE_DEV} | awk '{print $1}' | uniq | head -n1)"
ACTIVE_TYPE_1="$(nmcli dev status | grep -v disconnected | grep connected | awk '{print $2}' | uniq | head -n1)"
[ ${ACTIVE_TYPE_1} == "gsm" ] && ACTIVE_DEVICE_1="ppp0"

ACTIVE_DEVICE_2="$(nmcli dev status | grep -v disconnected | grep connected | grep -v ${IGNORE_DEV} | awk '{print $1}' | uniq | tail -n1)"
ACTIVE_TYPE_2="$(nmcli dev status | grep -v disconnected | grep connected | awk '{print $2}' | uniq | tail -n1)"
[ ${ACTIVE_TYPE_2} == "gsm" ] && ACTIVE_DEVICE_2="ppp0"


mygw_dev="$(route | grep default | awk '{print $8}')"
echo ${mygw_dev} > ${GW_DEV}
cp ${GW_DEV} ${WORKING_GW_DEV}



#A Actuve devices
if [ ${ACTIVE_TYPE_1} == "" ]
then 
	echo "NO ACTIVE DEVICE"
else
	ACTIVE_IP_1="$(ifconfig ${ACTIVE_DEVICE_1} | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1' | uniq)"
	echo ${ACTIVE_IP_1} > ${DEV_IP}
	echo ${ACTIVE_DEVICE_1} > ${ADEV}
	cp ${DEV_IP} ${WORKING_DEV_IP}
fi

# There is not second device
if [ "${ACTIVE_DEVICE_1}" == "${ACTIVE_DEVICE_2}" ]
then
	echo "NO ACTIVE SECOND DEVICE"

	echo "" > ${DEV_IP2}
	echo "" > ${ADEV2}
	cp ${DEV_IP} ${WORKING_DEV_IP2}
else
	
	if [ ${ACTIVE_TYPE_2} == "" ] 
	then 
		echo "NO ACTIVE SECOND DEVICE"
	else
		ACTIVE_IP_1="$(ifconfig ${ACTIVE_DEVICE_2} | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1' | uniq)"
		echo ${ACTIVE_IP_1} > ${DEV_IP2}
		echo ${ACTIVE_DEVICE_2} > ${ADEV2}
		cp ${DEV_IP} ${WORKING_DEV_IP2}
	fi

fi

sleep 1

# MAIN

while (true); do

    #export LC_MESSAGES="en_US.UTF-8"
    #export LC_TYPE="en_US.UTF-8"

	# Check the gotten internet IP
	#getip=$(curl -s http://www.ipchicken.com/ | awk '/[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ {print $1}' | uniq | grep -v curl)
	dig @ns1.google.com  2> /dev/null 1> /dev/null && getip="$(dig @ns1.google.com -t txt o-o.myaddr.l.google.com +short | sed s/\"/\/g)"
	echo ${getip} > ${GOT_IP}

    # Check the lokal IP and interfaces
	# Get the active device from network manager
	ACTIVE_DEVICE_1="$(nmcli dev status | grep -v disconnected | grep connected | grep -v ${IGNORE_DEV} | awk '{print $1}' | uniq | head -n1)"
	ACTIVE_TYPE_1="$(nmcli dev status | grep -v disconnected | grep connected | awk '{print $2}' | uniq | head -n1)"
	[ ${ACTIVE_TYPE_1} == "gsm" ] && ACTIVE_DEVICE_1="ppp0"

	ACTIVE_DEVICE_2="$(nmcli dev status | grep -v disconnected | grep connected | grep -v ${IGNORE_DEV} | awk '{print $1}' | uniq | tail -n1)"
	ACTIVE_TYPE_2="$(nmcli dev status | grep -v disconnected | grep connected | awk '{print $2}' | uniq | tail -n1)"
	[ ${ACTIVE_TYPE_2} == "gsm" ] && ACTIVE_DEVICE_2="ppp0"


	if [ ${ACTIVE_TYPE_1} == "" ] 
	then 
		break
	else
		ACTIVE_IP_1="$(ifconfig ${ACTIVE_DEVICE_1} | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1' | uniq | cut -f1)"
		echo ${ACTIVE_IP_1} > ${DEV_IP}
		echo ${ACTIVE_DEVICE_1} > ${ADEV}
	fi

	if [ ${ACTIVE_TYPE_2} == "" ] 
	then 
		break
	else
		ACTIVE_IP_2="$(ifconfig ${ACTIVE_DEVICE_2} | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1' | uniq | cut -f1)"
		echo ${ACTIVE_IP_2} > ${DEV_IP2}
		echo ${ACTIVE_DEVICE_2} > ${ADEV2}
	fi

    ########################################################################################
    ########################################################################################
    ## COMPARE STATES
    ########################################################################################

    ########################################################################################
    # Compare public internet ip
	gotip=$(cat ${GOT_IP})
    compare_getip=$(cat ${WORKING_IP})	

	if "$compare_getip" != "$gotip" 
	then 
		echo "######################################"

		if [ "${gotip}" == "" ]
		then
			echo "NO INTERNET CONNECTION"
		else
			echo "INTERNET IP CHANGED on ${ACTIVE_DEVICE_1} : ${ACTIVE_IP_1} to ${gotip}"
		fi

		cp ${GOT_IP} ${WORKING_IP}
		on_internet_adress_change

	else
		[ "${gotip}" == "" ] && echo "NO INTERNET CONNECTION"
		[ ${ACTIVE_DEVICE_1} != "" ]  && echo "Internet IP not changed on ${ACTIVE_DEVICE_1} : ${ACTIVE_IP_1} is ${gotip}"
	fi


    ########################################################################################	
	# Compare first local device

    devip=$(cat ${DEV_IP})
    compare_devip=$(cat ${WORKING_DEV_IP})

	if "$compare_devip" != "$devip" 
	then 
		echo "######################################"
		echo "IP OF DEVICE 1 CHANGED: ${ACTIVE_DEVICE_1} to ${ACTIVE_IP_1}"
		cp ${DEV_IP} ${WORKING_DEV_IP}
		on_local_address_change

	else
		[ "${gotip}" == "" ] && echo "NO INTERNET CONNECTION"
		[ ${ACTIVE_DEVICE_1} == "" ]  && echo "Local IP not changed on ${ACTIVE_DEVICE_1} : ${ACTIVE_IP_1}"
	fi


    ########################################################################################	
	# Compare second local device
    
    devip2=$(cat ${DEV_IP2})
    compare_devip2=$(cat ${WORKING_DEV_IP2})

	if "$compare_devip2" != "$devip2" 
	then 
		echo "######################################"
		echo "IP OF DEVICE 2 CHANGED: ${ACTIVE_DEVICE_2} to ${ACTIVE_IP_2}"
		cp ${DEV_IP2} ${WORKING_DEV_IP2}
		on_local_address_change

	else
		[ "${gotip}" == "" ] && echo "NO INTERNET CONNECTION"
		[ ${ACTIVE_DEVICE_2} == "" ]  && echo "Local IP not changed on ${ACTIVE_DEVICE_2} : ${ACTIVE_IP_2}"
	fi

    ########################################################################################
    # ROUTING
	ACTIVE_GATEWAY_DEV="$(route | grep default | awk '{print $8}')"
	echo ${ACTIVE_GATEWAY_DEV} > ${GW_DEV}

    gwdev=$(cat ${GW_DEV})
    compare_gwdev=$(cat ${WORKING_GW_DEV})

	# compare ROUTING
	if "$compare_gwdev" != "$gwdev" 
	then 
		echo "######################################"
		echo "DEFAUTL GATEWAY CHANGED to new device ${ACTIVE_DEVICE_1} to ${ACTIVE_IP_1}"
		cp ${GW_DEV} ${WORKING_GW_DEV}
		on_gw_change

	else
		[ "${gotip}" == "" ] && echo "NO INTERNET CONNECTION"
		[ ${ACTIVE_DEVICE_1} == "" ]  && echo "DEFAULT GATEWAY not changed on ${ACTIVE_GW_DEV}"
	fi


	sleep 10

done

Network Manager

Status of all devices 

export LC_MESSAGES="en_US@.UTF-8" \
export LC_TYPE="en_US.UTF-8" \
nmcli dev status


Testing network performance

There are a lot of possibilities to messure the network throughput on *nix machines. Some of the most valuable I am going to sumup in this article. Please read the corresponding links for further explanation at the end.

netperf

Installation: 

sudo apt-get install netperf
sudo apt-get install ethstatus

Start netperf as a daemon (ubuntu / debian way) 

sudo /etc/init.d/netperf start

Open a seperate terminal. 

ethstatus -i eth0

Then start from the server... 

netperf -H ip_of_client

...and vice versa on client 

netperf -H ip_of_server

The last column will show the througput in (power of ten)-bits/sec (which has to be divided through 8 to get byte/sec)

netcat

First approach

From client machine to server ...

On server: 

netcat -l -p 1234 > /dev/null

On client: 

dd if=/dev/zero bs=1M count=1000 |netcat server 1234

From server to client machine ... On client: 

netcat -l -p 1234 > /dev/null

On server: 

dd if=/dev/zero bs=1M count=1000 |netcat client 1234

You can exchange /dev/zero with e.g. /dev/md0 (for a raid device) or /dev/sda for testing your harddisk performance.

Second approach

1st computer. (The Server) 

nc -v -v -l -n -p 5096 >/dev/null

2nd computer. (The Client) 

time yes|nc -v -v -n 192.168.1.1 5096 >/dev/null
Ctrl+C

On the server note the rcvd. Multiply by 8 and divide by the time you see on your client. This are the maximal (theoretical) MB/s speed you will get for file transfers over the network.


iperf

Messures the network perfomance.

On the server do (start iperf in server mode) 

iperf -s

On the client machine do 

iperf -c server_ip -i 1 -t 10

Typical values

  • 15-25 Mbits/sec for a 54Mbit Wireless LAN
  • 300-350 Mbits/sec for a Gigabit LAN

The values depend heavily to

  • quality of the network card
  • quality of the cable (already CAT 6 !?) or wireless connection
  • bus speed
  • processor speed


ethtool

Ethtool gives you important informations over your network card, its settings and actual modes: 

ethtool eth0

sysctl

Settings for tpc ip settings: 

for i in rmem wmem mem; do sysctl net.ipv4.tcp_${i}; done

gives e.g. on an older machine (366MHz AMD K6, 33MHz bus) 

net.ipv4.tcp_rmem = 4096	87380	577600
net.ipv4.tcp_wmem = 4096	16384	577600
net.ipv4.tcp_mem = 13536	18050	27072

and on a "newer" system (AMD Athlon XP 2000+, 133MHz bus) 

net.ipv4.tcp_rmem = 4096	87380	4194304
net.ipv4.tcp_wmem = 4096	16384	4194304
net.ipv4.tcp_mem = 170592	227456	341184

I can be set with e.g.: 

sysctl -w net.ipv4.tcp_wmem="4096 16384 1048576"

But consider: better know what you are doing! On modern linux systems this should not be necessary.

MTU - Jumbo Frames

So called "Jumbo Frames" can reduce the CPU usage on the server. The network throughput is _NOT_ improved very much. Kernel greater than 2.6.17 support frame bigger than 1500 bythes.

Note, that both network card (driver) and used switches must support this kind of settings. Also it is not advisable to use this above large networks (internet connection might suffer). Better use this for direct connection between seperate NICs. Test e.g with 

ifconfig eth0 mtu 9044; echo -- DO SOME TESTS NOW --; sleep 120; ifconfig eth0 mtu 16436

16436 is the default setting on actual systems. Other good values seem to be 4022

Network configuration files /etc/sysconfig/network-script/ifcfg-eth0 (CentOS / RHEL / Fedora Linux) 

MTU=9044

Debian / Ubuntu Linux use /etc/network/interfaces configuration file. 

mtu 9044

Test with 

/etc/init.d/networking restart 
ip route get IP-address

Comparing with real (hard)drive performance

If you like to get the real disk perfance use e.g. 

dd if=/dev/zero of=3_2-GIG-file bs=1M count=3096

or 

dd if=/dev/sda of=/dev/null bs=1M
Ctrl + C

or read a file from a mounted directory 

dd if=a_huge_file of=/dev/null bs=1M

or with hdparm (the buffered disk read is for interest!): 

hdparm -tT /dev/disk

For realistic results you should also consider local disk read/writes for the operating system, other running tasks and that all components share the same (!) PCI bus. For that reason you have to sum up disk usage and network usage.

NFS performance

Mount options

For gigabit networks 

rsize=32768,wsize=32768
rsize=65536,wsize=65536

See [5], [7]

Seperate NICs

If you like to use two seperate NICs on an extra private subnet, e.g. 10.0.0.0/24 (25.255.255.0) to communicate for NFS, you should disable the packet forwarding in /proc/sys/net/ipv4/ip_forward 

sudo echo 0 >> /proc/sys/net/ipv4/ip_forward

Add the according NIC to your /etc/host 

10.0.0.10   mynfsserver
10.0.0.1    mynfsclient1

TIP: You don't have to use a switch instead of a crossover cable connecting two PCs for Gigabit connection. There is merely no difference in performance. For gigabit (!) you don't even have to use a crossover cable because the standard supports using normal cables!

Links

Retrieved from "https://wiki.blue-it.org/index.php?title=Network_Issues&oldid=5002"