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add snmpv3 support

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This commit is contained in:
Ian Gulliver
2025-11-29 21:16:58 -08:00
parent bf3cb600ad
commit c780fba93c
4 changed files with 299 additions and 1 deletions
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5
go.mod
View File

@@ -4,4 +4,7 @@ go 1.24.4
require github.com/google/gopacket v1.1.19
require golang.org/x/sys v0.0.0-20190412213103-97732733099d // indirect
require (
github.com/gosnmp/gosnmp v1.42.1 // indirect
golang.org/x/sys v0.13.0 // indirect
)

5
go.sum
View File

@@ -1,5 +1,7 @@
github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
github.com/gosnmp/gosnmp v1.42.1 h1:MEJxhpC5v1coL3tFRix08PYmky9nyb1TLRRgJAmXm8A=
github.com/gosnmp/gosnmp v1.42.1/go.mod h1:CxVS6bXqmWZlafUj9pZUnQX5e4fAltqPcijxWpCitDo=
golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
@@ -7,10 +9,13 @@ golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzB
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/net v0.0.0-20190620200207-3b0461eec859 h1:R/3boaszxrf1GEUWTVDzSKVwLmSJpwZ1yqXm8j0v2QI=
golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
golang.org/x/net v0.15.0 h1:ugBLEUaxABaB5AJqW9enI0ACdci2RUd4eP51NTBvuJ8=
golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

289
snmp.go Normal file
View File

@@ -0,0 +1,289 @@
package tendrils
import (
"context"
"fmt"
"log"
"net"
"time"
"github.com/gosnmp/gosnmp"
)
type snmpConfig struct {
username string
authKey string
privKey string
authProto gosnmp.SnmpV3AuthProtocol
privProto gosnmp.SnmpV3PrivProtocol
secLevel gosnmp.SnmpV3MsgFlags
timeout time.Duration
retries int
}
func defaultSNMPConfig() *snmpConfig {
return &snmpConfig{
username: "tendrils",
authKey: "tendrils",
privKey: "tendrils",
authProto: gosnmp.SHA512,
privProto: gosnmp.AES,
secLevel: gosnmp.AuthPriv,
timeout: 5 * time.Second,
retries: 1,
}
}
func (t *Tendrils) connectSNMP(ip net.IP) (*gosnmp.GoSNMP, error) {
cfg := defaultSNMPConfig()
snmp := &gosnmp.GoSNMP{
Target: ip.String(),
Port: 161,
Version: gosnmp.Version3,
Timeout: cfg.timeout,
Retries: cfg.retries,
SecurityModel: gosnmp.UserSecurityModel,
MsgFlags: cfg.secLevel,
SecurityParameters: &gosnmp.UsmSecurityParameters{
UserName: cfg.username,
AuthenticationProtocol: cfg.authProto,
AuthenticationPassphrase: cfg.authKey,
PrivacyProtocol: cfg.privProto,
PrivacyPassphrase: cfg.privKey,
},
}
err := snmp.Connect()
if err != nil {
return nil, err
}
return snmp, nil
}
func (t *Tendrils) pollSNMP(ctx context.Context) {
ticker := time.NewTicker(5 * time.Minute)
defer ticker.Stop()
t.querySwitches()
for {
select {
case <-ctx.Done():
return
case <-ticker.C:
t.querySwitches()
}
}
}
func (t *Tendrils) querySwitches() {
nodes := t.nodes.All()
for _, node := range nodes {
for _, ip := range node.IPs {
if ip.To4() == nil {
continue
}
go t.querySNMPDevice(ip)
}
}
}
func (t *Tendrils) querySNMPDevice(ip net.IP) {
snmp, err := t.connectSNMP(ip)
if err != nil {
return
}
defer snmp.Conn.Close()
t.queryBridgeMIB(snmp, ip)
t.queryARPTable(snmp, ip)
}
func (t *Tendrils) queryBridgeMIB(snmp *gosnmp.GoSNMP, deviceIP net.IP) {
macOID := "1.3.6.1.2.1.17.4.3.1.1"
portOID := "1.3.6.1.2.1.17.4.3.1.2"
macResults, err := snmp.BulkWalkAll(macOID)
if err != nil {
return
}
portResults, err := snmp.BulkWalkAll(portOID)
if err != nil {
return
}
portMap := make(map[string]int)
for _, result := range portResults {
if result.Type == gosnmp.Integer {
oidSuffix := result.Name[len(portOID)+1:]
portMap[oidSuffix] = result.Value.(int)
}
}
bridgePortToIfIndex := t.getBridgePortMapping(snmp)
ifNames := t.getInterfaceNames(snmp)
for _, result := range macResults {
if result.Type == gosnmp.OctetString {
macBytes := result.Value.([]byte)
if len(macBytes) != 6 {
continue
}
mac := net.HardwareAddr(macBytes)
if isBroadcastOrZero(mac) {
continue
}
oidSuffix := result.Name[len(macOID)+1:]
bridgePort, exists := portMap[oidSuffix]
if !exists {
continue
}
ifIndex, exists := bridgePortToIfIndex[bridgePort]
if !exists {
ifIndex = bridgePort
}
ifName := ifNames[ifIndex]
if ifName == "" {
ifName = "??"
}
t.nodes.Update(nil, []net.HardwareAddr{mac}, ifName, "", "snmp")
}
}
log.Printf("[snmp] queried bridge mib on %s", deviceIP)
}
func (t *Tendrils) queryARPTable(snmp *gosnmp.GoSNMP, deviceIP net.IP) {
macOID := "1.3.6.1.2.1.4.22.1.2"
ipOID := "1.3.6.1.2.1.4.22.1.3"
ifIndexOID := "1.3.6.1.2.1.4.22.1.1"
macResults, err := snmp.BulkWalkAll(macOID)
if err != nil {
return
}
ipResults, err := snmp.BulkWalkAll(ipOID)
if err != nil {
return
}
ifIndexResults, err := snmp.BulkWalkAll(ifIndexOID)
if err != nil {
return
}
ipMap := make(map[string]net.IP)
for _, result := range ipResults {
if result.Type == gosnmp.IPAddress {
oidSuffix := result.Name[len(ipOID)+1:]
ipBytes := result.Value.([]byte)
ipMap[oidSuffix] = net.IP(ipBytes)
}
}
ifIndexMap := make(map[string]int)
for _, result := range ifIndexResults {
if result.Type == gosnmp.Integer {
oidSuffix := result.Name[len(ifIndexOID)+1:]
ifIndexMap[oidSuffix] = result.Value.(int)
}
}
ifNames := t.getInterfaceNames(snmp)
for _, result := range macResults {
if result.Type == gosnmp.OctetString {
macBytes := result.Value.([]byte)
if len(macBytes) != 6 {
continue
}
mac := net.HardwareAddr(macBytes)
if isBroadcastOrZero(mac) {
continue
}
oidSuffix := result.Name[len(macOID)+1:]
ip, hasIP := ipMap[oidSuffix]
ifIndex, hasIfIndex := ifIndexMap[oidSuffix]
var ips []net.IP
if hasIP {
ips = []net.IP{ip}
}
ifName := ""
if hasIfIndex {
ifName = ifNames[ifIndex]
}
if ifName == "" {
ifName = "??"
}
t.nodes.Update(ips, []net.HardwareAddr{mac}, ifName, "", "snmp")
}
}
log.Printf("[snmp] queried arp table on %s", deviceIP)
}
func (t *Tendrils) getBridgePortMapping(snmp *gosnmp.GoSNMP) map[int]int {
oid := "1.3.6.1.2.1.17.1.4.1.2"
results, err := snmp.BulkWalkAll(oid)
if err != nil {
return nil
}
mapping := make(map[int]int)
for _, result := range results {
if result.Type == gosnmp.Integer {
oidParts := result.Name[len(oid)+1:]
var bridgePort int
_, err := fmt.Sscanf(oidParts, "%d", &bridgePort)
if err != nil {
continue
}
ifIndex := result.Value.(int)
mapping[bridgePort] = ifIndex
}
}
return mapping
}
func (t *Tendrils) getInterfaceNames(snmp *gosnmp.GoSNMP) map[int]string {
oid := "1.3.6.1.2.1.2.2.1.2"
results, err := snmp.BulkWalkAll(oid)
if err != nil {
return nil
}
names := make(map[int]string)
for _, result := range results {
if result.Type == gosnmp.OctetString {
oidParts := result.Name[len(oid)+1:]
var ifIndex int
_, err := fmt.Sscanf(oidParts, "%d", &ifIndex)
if err != nil {
continue
}
name := string(result.Value.([]byte))
names[ifIndex] = name
}
}
return names
}

1
tendrils.go
View File

@@ -24,6 +24,7 @@ func (t *Tendrils) Run() {
defer cancel()
go t.pollARP(ctx)
go t.pollSNMP(ctx)
ticker := time.NewTicker(1 * time.Second)
defer ticker.Stop()