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Let's say you do a traceroute scan to a network that is far away, and there a lot of intermediate hops, how do you know which one belongs to a BGP node, and which one is part of the target server? Let's say this for example, how would you know what is what?:

TRACEROUTE (using port 80/tcp)
HOP RTT       ADDRESS
1   3.00 ms   Linksys04870.home (10.136.1.1)
2   6.00 ms   192.168.1.1
3   ...
4   7.00 ms   10.255.200.190
5   7.00 ms   10.34.201.1
6   8.00 ms   10.34.65.181
7   8.00 ms   bundle-ether102-14.bartr2.barcelona.opentransit.net (81.52.179.129)
8   21.00 ms  193.251.132.7
9   28.00 ms  ae-7.edge1.Madrid1.Level3.net (4.68.73.97)
10  165.00 ms ae1.37.bar4.SaltLakeCity1.level3.net (4.69.219.58)
11  165.00 ms 4.53.7.174
12  164.00 ms 69-195-64-111.unifiedlayer.com (69.195.64.111)
13  164.00 ms po99.prv-leaf2a.net.unifiedlayer.com (162.144.240.79)
14  164.00 ms 162-240-147-30.unifiedlayer.com (162.240.147.30)
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  • You really have no way to know how a router populates its routing table, with static BGP, OSPF, RIP, EIGRP, IS-IS, etc. All you know is the router sent back an ICMP error message to your traceoute. Remember, routing protocols do not route packets; routers route packet based on what is in their routing tables, and how a route gets into the routing table you cannot know without access to the router.
    – Ron Maupin
    Oct 31, 2023 at 22:43

1 Answer 1

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Generally, you can't tell whether a node uses BGP to exchange routes or any other means.

Between providers/carriers BGP is likely used but you can't be sure.

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  • How do BGP route hijackings work tho? Like do they first need to know the IP Addresses of the BGP peers?
    – 19216811
    Nov 1, 2023 at 9:59
  • That's an entirely different question. Adjacent BGP peers need to be configured in order to talk to each other.
    – Zac67
    Nov 1, 2023 at 10:49

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