BGP Hijack/Sickness with AS4637


 We're looking for a contact, \*that works\*, to get in touch with AS4637 \(Telstra/HK\) about some hijacking or router sickness\.

 BGPmon has been reporting an hijack of AS3's subnet 18\.29\.238\.0/23\.

 After being contacted by AS3, we went over the advertisement with AS29909 and AS16532 to be sure\.

 Then we tried getting in touch with AS4637 \(Telstra/HK\) but it went nowhere at this point\.

 PS: If anyone has better observations that would be greatly appreciated\.


Actually, what you have provided below shows the exact opposite. It shows ColoAU have received the route from 4637 who have received it from 3257 who have received it from 29909 who have received it from 16532 who originated it. It infers nothing about who 16532 found the route to come from.

It is evident that GTT are advertising that route to Telstra Global :slight_smile:


There is a good possibility that AS 16532 was trying to prepend 3 times and did prepend 16532 3 instead of prepend 16532 16532 16532.
That tends to happen with very low number AS



This looks like a route that has been cached by some ISPs/routers even
though a withdrawal has actually happened.

If you actually forward packets a long the path, you'll see its not
following the AS Path suggested, instead the real route that it should be.
Bouncing your session with 4637 would likely clear this.



I am the contact for AS16532.

We never announced nor are we currently advertising this prefix as we are not a transit AS for anyone. As well, it seems to appear and disappear from AS63956 looking glass. According to that LG, the route changed 6d ago, and is *still currently visible* at this very moment;

Command: show route protocol bgp table vrf-international.inet.0 active-path

vrf-international.inet.0: 696764 destinations, 2288960 routes (696480 active, 0 holddown, 103994 hidden)
+ = Active Route, - = Last Active, * = Both *[BGP/170] 6d 01:06:11, localpref 90, from
                      AS path: 4637 3257 29909 16532 16532 16532 16532 I, validation-state: unverified

AS16532 is not announcing this prefix. We have a strict prefix-list that is applied to all sessions. As well, AS29909 is filtering us using our announced AS-SETS/RPSL to avoid us the ability to do anything dumb. And lastly, our announcements are being filtered by AS3257 as we are required to provide them via LOA.

There is still something wrong somewhere that is injecting this path, anyone have a LG pointed to AS4637 seeing this prefix announced with AS16532 in the AS path?

I doubt that AS29909 bouncing its BGP session with AS3257 (GTT) would change anything, as I am not seeing this prefix in their route-server> show route protocol bgp active-path

inet.0: 691667 destinations, 11752983 routes (691665 active, 1 holddown, 1 hidden)
+ = Active Route, - = Last Active, * = Both *[BGP/170] 3w4d 11:42:33, MED 0, localpref 100, from
                      AS path: 3257 174 3 I, validation-state: unverified
                    > to via xe-1/0/0.0


{master}> show route protocol bgp | find 16532

Pattern not found

So whatever is happening, its not at AS16532, AS29909 nor AS3257 that I can find.

Chris Conn


 Well bad news on the ColoAU front, they refused to cooperate\.

 We'll pushback thru our GTT accounts\.\.\.  But I'm running out of ideas\.

 If anyone has any good ideas how to proceed at this point feel free to share =D\.

What is the relationship of (Colocation Australia - Japan) to you? Is this, for example, a peering over an IX? If so, did you learn the route from route servers or do you peer directly with them?



 None beside they're advertising a fake route of part of a MIT subnet using ASNs I care about\.  \(Which include GTT and MIT\)

 Right now their getting it from their outfit in JP which do not have a LG, and we cannot find any other crumbs in most LG found on lookingglass\.org\.

 Without any cooperation from the only place we can see it, there isn't much we can do\.

 PS; Might be a generational gap, but in the olden days we used to be able to get cooperation from other operators\.

Well bad news on the ColoAU front, they refused to cooperate.

We'll pushback thru our GTT accounts...� But I'm running out of ideas.

If anyone has any good ideas how to proceed at this point feel free to
share =D.

This feels like a BGP "optimiser" at work inside AS 4637.

From the looking glass:

BGP 'show route' *[BGP/170] 1w0d 18:49:44, localpref 90, from
                    AS path: 4637 3257 29909 16532 16532 16532 16532 I, validation-state: unverified

However, a data-plane traceroute:

    AS path: 4637 -> 174 -> ...

    traceroute to (, 30 hops max, 40 byte packets
     1 ( 114.573 ms 113.965 ms 117.141 ms
         MPLS Label=691873 CoS=0 TTL=1 S=0
         MPLS Label=17 CoS=0 TTL=1 S=1
     2 ( 113.768 ms 113.763 ms 113.731 ms
     3 ( [AS 4637] 114.759 ms 117.956 ms 115.796 ms
     4 ( [AS 4637] 181.873 ms ( [AS 4637] 181.618 ms 182.688 ms
     5 ( [AS 4637] 181.949 ms ( [AS 4637] 183.194 ms ( [AS 4637] 201.282 ms
     6 ( [AS 174] 181.055 ms 181.100 ms 181.065 ms
     7 ( [AS 174] 175.410 ms 182.956 ms ( [AS 174] 175.176 ms
     8 ( [AS 174] 212.531 ms ( [AS 174] 202.470 ms 187.361 ms
     9 ( [AS 174] 195.585 ms 195.812 ms ( [AS 174] 211.713 ms
    10 ( [AS 174] 235.896 ms 216.173 ms 211.246 ms
    11 ( [AS 174] 233.516 ms 225.413 ms 225.551 ms
    12 ( [AS 174] 236.432 ms 236.701 ms 236.595 ms
    13 ( [AS 174] 273.564 ms 279.452 ms 248.212 ms
    14 ( [AS 174] 248.098 ms 247.802 ms 248.084 ms
    15 * * *

Discongruity between RIB and FIB like this, and the hijack being a
more-specific of a /16, is a typical sign of BGP 'optimisers'.

I recommend you reach out to AUSNOG and APOPS and hope someone there
knows someone at Telstra Hong Kong.

More thoughts on BGP optimisers: nanog: BGP Optimizers (Was: Validating possible BGP MITM attack)

Kind regards,


Thanks for the ideas and the hint\.  Good read\.

 Will do\.

 PS: Still curious how, beside some RIB/FIB failure, how our AS ended up there\.

I have a friend at Telstra HKG. He's not in the IP team, but he can
summon a warm body if needed.


Thanks for the ideas and the hint.� Good read.

Will do.

Upon further inspection, it seems more likely that the bgp optimiser is
in ColoAU's network. Given the scale of AS 4637, if it were deployed
inside Telstra I'd expect more problem reports. AS 4637 may actually
just be an innocent bystander.

It is interesting to note that the /23 only appears on their Sydney
based routers on

Is ColoAU's refusal to cooperate a matter of misunderstanding? Perhaps
you should just straight up ask whether they use any type of "network
optimisation" appliance.

PS: Still curious how, beside some RIB/FIB failure, how our AS ended
up there.

I don't know why, but often fabricating random AS_PATH stuff seems to be
part of it.

Kind regards,


We've suffered this many times as well, particularly when records show
up on HE's BGP tool.

It's a b**ch to get fixed, because too many fingers get pointed, and
folk running BGP optimizers may not fully understand this side effect.


I found a few more interesting routes inside ColoAU's looking glass: - AS_PATH 63956 4637 3257 29909 16532 16532 16532 16532
                (should be originated by AS 17, Purdue
                University) - AS path: 135069 9439
        (does not exist in the DFZ, a peering lan prefix? a typo?) - AS path: 2764 1221 36692
        (does not exist in the DFZ, a peering lan prefix? a typo?)

ColoAU propagated the above routes to their transit customers, so the and announcements definitely count as BGP
hijacks with fabricated an AS_PATH.

Kind regards,



Just to clear up a few things. We are not running any route optimization software (ever). The reason we "refused" to help is because we were not going to contact our transit providers NOC regarding other parties routes, even if we did they wouldn't be of assistance.

We are purely passing on the routes we receive from our transit providers to our customers. We are not modifying the routes in any way shape or form.

We incest routes from a lot of transit providers and send most of the data to route views (As do a number of our customers) which is why this route was seen from us.

I have completed a soft clear on our BGP session towards AS4637 and the route still exists. Sorry we can't be of assistance in this case but this is fully out of our control.> show route detail

vrf-international.inet.0: 696465 destinations, 1194388 routes (696461 active, 0 holddown, 4 hidden) (1 entry, 1 announced)
*BGP Preference: 170/-101
Next hop type: Router, Next hop index: 790
Address: 0xff29810
Next-hop reference count: 1279932
Next hop: via ae0.401, selected
Session Id: 0x181
State: <Active Ext>
Peer AS: 4637
Age: 2w4d 11:08:17
Validation State: unverified
Task: BGP_4637.
Announcement bits (4): 1-KRT 2-BGP Route Target 5-BGP_RT_Background 6-Resolve tree 6
AS path: 4637 3257 29909 16532 16532 16532 16532 I
Communities: 4637:32031 4637:32314 4637:32504 4637:60952
Localpref: 100
Router ID:

ColoAU (AS63956)

Colocation Australia Pty Ltd <>

Brad Hooper / Network Architect <>/ +61 7 3106 3810

Colocation Australia Pty Ltd

Facebook <> Twitter <> skype <skype:coloau-brad?call>


 Looks like it was a RIB&lt;\-&gt;FIB bug in part\.

 How: BGP Optimizator maybe a culprit, but without insights from ColoAU it is hard to say\.

 Thank to Job, Mark, Tracey for their time\.