Dual NIC clients

Wayne Workman

@Quazz do we know of any linux kernel arguments that specify only using a particular nic, or disabling a particular nic?

Maybe even a custom kernel could be an answer? Or custom init?

Quazz

@Wayne-Workman The problem is, what arguments can we use to differentiate? It sounds like they’re basically identical NICs connecting to different network outlets, probably getting inconsistent names as well. (based on his results)

https://www.kernel.org/doc/Documentation/kernel-parameters.txt

Scroll down to grcan.enable0

Looks like those options are useful?

Wayne Workman

@Quazz very nice. I read it’s description, but the one below it caught my eye:

grcan.select= [HW] Select which physical interface to use. Format: 0 | 1 Default: 0

So perhaps try this for the host’s kernel arguments (web gui -> host management -> desired host -> kernel arguments)

grcan.select=1

See what happens?

tag

@Quazz and @Wayne-Workman

Thanks for the suggestions.

I tried playing around with grcan.enable0=[0|1] and grcan.enable1=[0|1] as well as grcan.select=[0|1] but none had any effect. The kernel continues to choose the slower link in most cases. Seemed promising, though…

What I do notice for the first time, though, is that whatever NIC is not chosen is disabled. I hadn’t noticed as I can’t see the backs of the boxes very well. Here it is also obvious that the active NIC changes on occasion, as the LEDs die on the disabled NIC.

Wayne Workman

@tag I think you’re going to have to build a custom init. You can change the fog.upload and fog.download scripts. The idea would be to use shell script to determine which interface is on the right network, and then disable the other interface (or enable it). It should be pretty simple.

How experienced are you with shell scripting?

Also, here’s a link on how to unpack and re-pack the inits:
https://wiki.fogproject.org/wiki/index.php?title=Build_FOG_file_system_with_BuildRoot

I’m willing to help do this - but I wouldn’t have time until tonight to mess with it.

tag

@Wayne-Workman

Thanks for the reply.

Seems kind of inflexible, though… The same init is used for all, right? We even have some clients with three NICs at other locations… If it has to take various hw scenarios into account, it might take some fancy scripting.

I know some basic scripting but nothing really fancy.

The only way to determine the correct interface would be to filter on IP, as I see it.

So maybe a list of interfaces and then for each ethX in the list:

#!/bin/csh

set nwid = X.X.X
set list = (eth0 eth1)

foreach eth ($list)
  set ip = `ifconfig $eth | grep inet | awk '{print $2}' | sed 's/addr://' | cut -c-10 `
  if ($ip == $nwid) then
      ifup $eth else
      ifdown $eth
  endif
end

That would in my case get the network ID of the correct network and other disimilar outputs from the other interfaces in the list which could then be compared to a set value of the correct network ID. Based on that comparison you could then turn on or off the interfaces.

I’m sure someone else could do something a lot niftier.

I haven’t tested any of this and it might screw up if the number of interfaces actually present is different from the number in the list.

Wayne Workman

@tag You’ve got the right idea - but that specific code is inflexible.

Tonight I’ll put something together that will take the IPs, and the subnet mask, and calculate the subnet ID and use that for comparison.

tag

@Wayne-Workman
Thanks again.

Yes, that code will only work on the specific network defined in $nwid and if the kernel names the interfaces ethX and probably only if the number of interfaces match that particular piece of hw…

Mighty nice of you to help me out here… Appreciate it.

Thanks.

Wayne Workman

@tag Well the way I write it, it’ll work with however many NICs a system has. We will need to use the new feature that @Tom-Elliott so kindly implemented maybe a month ago, the host’s Host Init field. Basically we will build an init for each of your subnets, then use groups to assign the right inits to the right computers - so that those computers in those subnets use the correct interface.

Sounds like a lot - but I really don’t think it is. I think this is going to be very easy.

Wayne Workman

I’ve been working on this.

This is my first go-round with a custom init so I’m asking that @Sebastian-Roth and @Tom-Elliott and @george1421 to take a look, too.

I’ve not tested, as I don’t readily have available a machine with multiple interfaces, but I think I’ve got a universal init that you can pass a custom kernel argument to, which will ensure the correct interface is up, and others are down. So far, I’ve coded for three possible interfaces. I already had many of these functions already written in another project I’ve been working on.

in the init, I’ve edited the file /usr/share/fog/lib/funcs.sh to include these functions:

cidr2mask() {
        #Expects CIDR notation (a single integer between 0 and 32)
        local i=""
        local mask=""
        local full_octets=$(($1/8))
        local partial_octet=$(($1%8))
        for ((i=0;i<4;i+=1)); do
        if [[ $i -lt $full_octets ]]; then
                mask+=255
        elif [[ $i -eq $full_octets ]]; then
                mask+=$((256 - 2**(8-$partial_octet)))
        else
                mask+=0
        fi
                test $i -lt 3 && mask+=.
        done
        echo $mask
}

getCidr() {
        #Expects an interface name to be passed.
        local cidr
        cidr=$(ip -f inet -o addr | grep $1 | awk -F'[ /]+' '/global/ {print $5}' | head -n2 | tail -n1)
        echo $cidr
}
mask2network() {
        #Expects IP address passed 1st, and Subnet Mask passed 2nd.
        OIFS=$IFS
        IFS='.'
        read -r i1 i2 i3 i4 <<< "$1"
        read -r m1 m2 m3 m4 <<< "$2"
        IFS=$OIFS
        printf "%d.%d.%d.%d\n"  "$((i1 & m1))" "$((i2 & m2))" "$((i3 & m3))" "$((i4 & m4))"
}
GetInterfaceInfo() {
	DIR="/"

	ip link show > $DIR/interfaces.txt

	interface1name="$(sed -n '3p' $DIR/interfaces.txt)"
	interface2name="$(sed -n '5p' $DIR/interfaces.txt)"
	interface3name="$(sed -n '7p' $DIR/interfaces.txt)"


	rm -f $DIR/interfaces.txt

	echo $interface1name | cut -d \: -f2 | cut -c2- > $DIR/interface1name.txt
	echo $interface2name | cut -d \: -f2 | cut -c2- > $DIR/interface2name.txt
	echo $interface3name | cut -d \: -f2 | cut -c2- > $DIR/interface3name.txt	

	interface1name="$(cat $DIR/interface1name.txt)"
	interface2name="$(cat $DIR/interface2name.txt)"
	interface2name="$(cat $DIR/interface2name.txt)"

	rm -f $DIR/interface1name.txt
	rm -f $DIR/interface2name.txt
	rm -f $DIR/interface3name.txt

	#Bring up interfaces.

	echo “iface $interface1name inet dhcp” >>/etc/network/interfaces
	echo “iface $interface2name inet dhcp” >>/etc/network/interfaces
	echo “iface $interface3name inet dhcp” >>/etc/network/interfaces



	ip link set $interface1name up
	ip link set $interface2name up
	ip link set $interface3name up
	sleep 4




	interface1ip="$(/sbin/ip addr show | grep $interface1name | grep -o "inet [0-9]*\.[0-9]*\.[0-9]*\.[0-9]*" | grep -o "[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*")"

	interface2ip="$(/sbin/ip addr show | grep $interface2name | grep -o "inet [0-9]*\.[0-9]*\.[0-9]*\.[0-9]*" | grep -o "[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*")"

	interface3ip="$(/sbin/ip addr show | grep $interface3name | grep -o "inet [0-9]*\.[0-9]*\.[0-9]*\.[0-9]*" | grep -o "[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*")"


	if [[ -z $interface1ip ]]; then
		interface1ip=127.0.0.1
	fi

	if [[ -z $interface2ip ]]; then 
		interface2ip=127.0.0.1
	fi

	if [[ -z $interface3ip ]]; then 
                interface3ip=127.0.0.1
        fi
	
	interface1network=$(mask2network $interface1ip $(cidr2mask $(getCidr $interface1name)))
	interface2network=$(mask2network $interface2ip $(cidr2mask $(getCidr $interface2name)))
	interface3network=$(mask2network $interface3ip $(cidr2mask $(getCidr $interface3name)))





}

setCorrectInterface() {
for arg in $(cat /proc/cmdline) do  
    echo $arg | grep -q USE_NETWORK
    if [ $? == 0 ] then      
        val=$(echo $arg | cut -d= -f2)
        desiredNetwork=$val
    fi
done

GetInterfaceInfo

if [[ $interface1network==$desiredNetwork ]] then
        ip link set $interface1name up
        ip link set $interface2name down
        ip link set $interface3name down
elif [[ $interface2network==$desiredNetwork ]] then
	ip link set $interface1name down
       	ip link set $interface2name up
        ip link set $interface3name down
else [[ $interface3network==$desiredNetwork ]] then
	ip link set $interface1name down
        ip link set $interface2name down
        ip link set $interface3name up
fi



}

And I’ve added a call to the main function in the main fog script file /bin/fog between the usb part and the task calling, around line 10 like this:

#!/bin/bash
. /usr/share/fog/lib/funcs.sh
### If USB Boot device we need a way to get the kernel args properly
if [[ $boottype == usb && ! -z $web ]]; then
    mac=$(getMACAddresses)
    wget -q -O /tmp/hinfo.txt "http://${web}service/hostinfo.php?mac=$mac"
    [[ -f /tmp/hinfo.txt ]] && . /tmp/hinfo.txt
fi

setCorrectInterface

if [[ -n $mode && $mode != +(*debug*) ]]; then
    case $mode in
        wipe)
            fog.wipe
            ;;
        checkdisk)
            fog.testdisk
            ;;
        photorec)
            fog.photorec
            ;;
        badblocks)
            fog.surfacetest
            ;;
        clamav)
            fog.av
            ;;
        autoreg)
            fog.auto.reg
            ;;
        manreg)
            fog.man.reg
            ;;
        inventory)
            fog.inventory
            ;;
        capone)
            fog.capone
            ;;
        winpassreset)
            fog.chntpw
            ;;
        quickimage)
            fog.quickimage
            ;;
        sysinfo)
            fog.sysinfo
            ;;
        "donate.full")
            fog.donatefull
            ;;
        *)
            handleError "Fatal Error: Unknown mode :: $mode ($0)\n   Args Passed: $*"
            ;;
    esac
else
    case $type in
        down)
            fog.download
            ;;
        up)
            fog.upload
            ;;
        *)
            [[ -z $type ]] && type="Null"
            handleError "Fatal Error: Unknown request type :: $type"
            ;;
    esac
fi

With modifications to the init like this (and using fog trunk), You’d simply specify this custom init, and pass the kernel argument for the network you want to use. For example:

tag

@Wayne-Workman

That would work nicely, seeing you can use different inits. I didn’t know that as it is not possible in 1.2.0.

The caveat is that I would have to redo the server as trunk requires a newer Ubuntu according to @Quazz.

Wayne Workman

@tag correct. No getting around that.

Dual NIC clients

147

12.1k

17.3k

155.3k