[c-nsp] SNMP: IP => vlan + mac

[Virgil]

> Is there a posibility to obtain via SNMP a mac-address 
> (0007.eb95.9b80) from arp table for IP address 10.5.16.7 ?


This might be of use to you.  It's a dodgy shell script that's crying
out to be converted to perl net-snmp.
If anyone feels the urge, please send me a copy.

#!/bin/bash
# locates a switch port in the access layer from an IP address.
# query starts at the core 6500

READONLY=public
SW=$1
IPADDRESS=$2


arpMeBaby() {
        #MAC address of ${IPADDRESS}
        snmpwalk -On -v2c -c${READONLY} ${1} atPhysAddress | grep "${2}
=" | cut -d" " -f4-
}


getVlanif() {
        snmpwalk -Onq -v2c -c${READONLY} ${1} ipNetToMediaPhysAddress |
grep "${2} " | awk ' {split($1,vi,".1.3.6.1.2.1.4.22.1.2."); print
vi[2]}'  | awk 'BEGIN { FS = "." } ; { print $1}'
}


getVlan() {
        #IF-MIB::ifName.204 = STRING: Vl11
        snmpwalk -On -v2c -c${READONLY} ${1} ifName.${2} | awk '{print
$4}' | cut -c3-
}


macSuck() {
        #For this VLAN, get the MAC address table (using community
string indexing!) dot1dTpFdbAddress
        snmpwalk -On -v2c -c${READONLY}@${Vlan} ${1}
.1.3.6.1.2.1.17.4.3.1.1 | grep "${2}" | cut -d"." -f13-18 | cut -d" "
-f1
}

whichPort() {
        #Get the bridge port number, dot1dTpFdbPort
(.1.3.6.1.2.1.17.4.3.1.2) for this MAC
        snmpwalk -Onv -v2c -c${READONLY}@${2} ${1}
.1.3.6.1.2.1.17.4.3.1.2.${3} | cut -d" " -f2
}

findifIndex() {
        #For this VLAN, get the bridge port to ifIndex
(1.3.6.1.2.1.2.2.1.1) mapping,
        #dot1dBasePortIfIndex (.1.3.6.1.2.1.17.1.4.1.2):
        snmpwalk -Ovn -v2c -c${READONLY}@${2} ${1}
.1.3.6.1.2.1.17.1.4.1.2.${3} | cut -d" " -f2
}

portName() {
        #Walk the ifName (.1.3.6.1.2.1.31.1.1.1.1) so that the ifIndex
value
        #can be correllated with a proper port name:
        snmpwalk -Oqn -v2c -c${READONLY}@${2} ${1} ifName.${3} | cut -d"
" -f2
}

portDesc() {
        #Get the description (.1.3.6.1.2.1.31.1.1.1.18)
        snmpwalk -Oqn -v2c -c${READONLY}@${2} ${1} ifAlias.${3} | cut
-d" " -f2-
}

cdpNei() {
        #Find the CDP neighbor (.1.3.6.1.4.1.9.9.23.1.2.1.1.6) for the
next hop.
        snmpwalk -Ovn -v2c -c${READONLY}@${2} ${1}
1.3.6.1.4.1.9.9.23.1.2.1.1.6.${3} | cut -f2 -d\"
}
cdpNeiPort() {
        snmpwalk -Ovn -v2c -c${READONLY}@${2} ${1}
1.3.6.1.4.1.9.9.23.1.2.1.1.7.${3} | cut -f2 -d\"
}

target=${SW}

VlanifIndex=`getVlanif ${target} ${IPADDRESS}`
Vlan=`getVlan ${target} $VlanifIndex`
Arp=`arpMeBaby ${target} ${IPADDRESS}`
MAC=`macSuck ${target} "${Arp}"`
PortNo=`whichPort ${target} ${Vlan} $MAC`
ifIndex=`findifIndex ${target} ${Vlan} $PortNo`
if=`portName ${target} ${Vlan} $ifIndex`
ifDesc=`portDesc ${target} ${Vlan} $ifIndex`
CdpNei=`cdpNei ${target} ${Vlan} $ifIndex`
CdpNeiPort=`cdpNeiPort ${target} ${Vlan} $ifIndex`

target=${CdpNei}
AccessSwPortNo=`whichPort ${target} ${Vlan} $MAC`
AccessSwifIndex=`findifIndex ${target} ${Vlan} $AccessSwPortNo`
AccessSwif=`portName ${target} ${Vlan} $AccessSwifIndex`
AccessSwifDesc=`portDesc ${target} ${Vlan} $AccessSwifIndex`

#echo -ne "${IPADDRESS} is in Vlan ${Vlan}\n${SW} [${if}] -> ${CdpNei}
[${CdpNeiPort}]\n${CdpNei} [$AccessSwif] -> ${AccessSwifDesc}\n"

echo -ne "$target [$AccessSwif] -> ${AccessSwifDesc}\n"

Regards,

Virgil

-- 
WebCentral Pty Ltd           Australia's #1 Internet Web Hosting Company
Level 6, 100 Wickham St.                 Infrastructure Projects Manager
PO Box 930, Fortitude Valley.            email: virgil at webcentral.com.au
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