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Merge pull request #36 from satta/rdns
implement active reverse DNS enrichment
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,110 @@ | ||
| package processing | ||
|
|
||
| // DCSO FEVER | ||
| // Copyright (c) 2019, DCSO GmbH | ||
|
|
||
| import ( | ||
| "net" | ||
| "sync" | ||
|
|
||
| "github.com/DCSO/fever/types" | ||
| "github.com/DCSO/fever/util" | ||
|
|
||
| log "github.com/sirupsen/logrus" | ||
| "github.com/yl2chen/cidranger" | ||
| ) | ||
|
|
||
| // RDNSHandler is a handler that enriches events with reverse DNS | ||
| // information looked up on the sensor, for both source and destination | ||
| // IP addresses. | ||
| type RDNSHandler struct { | ||
| sync.Mutex | ||
| Logger *log.Entry | ||
| HostNamer *util.HostNamer | ||
| PrivateRanges cidranger.Ranger | ||
| PrivateRangesOnly bool | ||
| } | ||
|
|
||
| // MakeRDNSHandler returns a new RDNSHandler, backed by the passed HostNamer. | ||
| func MakeRDNSHandler(hn *util.HostNamer) *RDNSHandler { | ||
| rh := &RDNSHandler{ | ||
| Logger: log.WithFields(log.Fields{ | ||
| "domain": "rdns", | ||
| }), | ||
| PrivateRanges: cidranger.NewPCTrieRanger(), | ||
| HostNamer: hn, | ||
| } | ||
| for _, cidr := range []string{ | ||
| "10.0.0.0/8", | ||
| "172.16.0.0/12", | ||
| "192.168.0.0/16", | ||
| "fc00::/7", | ||
| } { | ||
| _, block, err := net.ParseCIDR(cidr) | ||
| if err != nil { | ||
| log.Fatalf("cannot parse fixed private IP range %v", cidr) | ||
| } | ||
| rh.PrivateRanges.Insert(cidranger.NewBasicRangerEntry(*block)) | ||
| } | ||
| return rh | ||
| } | ||
|
|
||
| // EnableOnlyPrivateIPRanges ensures that only private (RFC1918) IP ranges | ||
| // are enriched | ||
| func (a *RDNSHandler) EnableOnlyPrivateIPRanges() { | ||
| a.PrivateRangesOnly = true | ||
| } | ||
|
|
||
| // Consume processes an Entry and enriches it | ||
| func (a *RDNSHandler) Consume(e *types.Entry) error { | ||
| var res []string | ||
| var err error | ||
| var isPrivate bool | ||
|
|
||
| if e.SrcIP != "" { | ||
| ip := net.ParseIP(e.SrcIP) | ||
| if ip != nil { | ||
| isPrivate, err = a.PrivateRanges.Contains(ip) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if !a.PrivateRangesOnly || isPrivate { | ||
| res, err = a.HostNamer.GetHostname(e.SrcIP) | ||
| if err == nil { | ||
| e.SrcHosts = res | ||
| } | ||
| } | ||
| } else { | ||
| log.Error("IP not valid") | ||
| } | ||
| } | ||
| if e.DestIP != "" { | ||
| ip := net.ParseIP(e.DestIP) | ||
| if ip != nil { | ||
| isPrivate, err = a.PrivateRanges.Contains(ip) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if !a.PrivateRangesOnly || isPrivate { | ||
| res, err = a.HostNamer.GetHostname(e.DestIP) | ||
| if err == nil { | ||
| e.DestHosts = res | ||
| } | ||
| } | ||
| } else { | ||
| log.Error("IP not valid") | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // GetName returns the name of the handler | ||
| func (a *RDNSHandler) GetName() string { | ||
| return "reverse DNS handler" | ||
| } | ||
|
|
||
| // GetEventTypes returns a slice of event type strings that this handler | ||
| // should be applied to | ||
| func (a *RDNSHandler) GetEventTypes() []string { | ||
| return []string{"http", "dns", "tls", "smtp", "flow", "ssh", "tls", "smb", "alert"} | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,51 @@ | ||
| package util | ||
|
|
||
| import ( | ||
| "net" | ||
| "strings" | ||
| "sync" | ||
| "time" | ||
|
|
||
| "github.com/patrickmn/go-cache" | ||
| ) | ||
|
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| // HostNamer is a component that provides cached hostnames for IP | ||
| // addresses passed as strings. | ||
| type HostNamer struct { | ||
| Cache *cache.Cache | ||
| Lock sync.Mutex | ||
| } | ||
|
|
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| // NewHostNamer returns a new HostNamer with the given default expiration time. | ||
| // Data entries will be purged after each cleanupInterval. | ||
| func NewHostNamer(defaultExpiration, cleanupInterval time.Duration) *HostNamer { | ||
| return &HostNamer{ | ||
| Cache: cache.New(defaultExpiration, cleanupInterval), | ||
| } | ||
| } | ||
|
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| // GetHostname returns a list of host names for a given IP address. | ||
| func (n *HostNamer) GetHostname(ipAddr string) ([]string, error) { | ||
| n.Lock.Lock() | ||
| defer n.Lock.Unlock() | ||
|
|
||
| val, found := n.Cache.Get(ipAddr) | ||
| if found { | ||
| return val.([]string), nil | ||
| } | ||
| hns, err := net.LookupAddr(ipAddr) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| for i, hn := range hns { | ||
| hns[i] = strings.TrimRight(hn, ".") | ||
| } | ||
| n.Cache.Set(ipAddr, hns, cache.DefaultExpiration) | ||
| val = hns | ||
| return val.([]string), nil | ||
| } | ||
|
|
||
| // Flush clears the cache of a HostNamer. | ||
| func (n *HostNamer) Flush() { | ||
| n.Cache.Flush() | ||
| } |
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