AS15958 - CETIN_doo_AS CETINPARFC 4890 ✓RPKI ✓ 1/1ASPA -

AS overview

Test target: 2a01:ac80::1 · static prefix probe · address space: PA · prefixes announced: 1

prefix(es): 2a01:ac80::/32

SOX peering

Random-IP probe (yarrp) into the AS' prefixes

We probed 35 arbitrary IPv6 address(es) inside AS15958's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2001:7f8:35::1:5958:2 at hop 8 - that router does not answer ICMPv6 Echo. This is not in AS15958's announced prefix; operationally it's the AS-edge / peering interface (often on a SOX peering address or an upstream's /127 link). The traceroute boundary is the AS edge: ICMPv6 Time-Exceeded responses from anything inside this AS are filtered.

ICMPv6 Type 2 (Packet Too Big) acceptance - active test

Vantage points disagree about Type 2 acceptance - transit ASes on one path may be filtering Type 2 even though the destination's stack accepts it on another path:

• SRB host (SOX, Belgrade): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
• DE host (Berlin): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
• DE host (Düsseldorf): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
• NL host (go6lab): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
• ITA host (Karsolink): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
• SLO host (6connect): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
• SLO host (T-2): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)

Why they disagree - path-asymmetric Type 2 filtering: Both vantages used the ICMPv6 Echo + forged-PTB method on the same destination IP, but reached different verdicts. The destination's stack is the same in both cases - so the difference is in the path: a transit AS on one route filters our forged Type 2 (or its return ICMPv6 carrying the embedded packet) while the other route delivers it intact. The vantage that says honored shows what the destination's stack actually does; the one that says not honored shows that the path between us and them drops Type 2.

sudo tcpdump -i any -n -e 'icmp6 and ip6[40] = 2 and (src host 2607:fae0:a000::42 or src host 2a00:8642:42::75 or src host 2a01:261:313:b814:2a0:98ff:fe5b:13e4 or src host 2a06:d1c1:10b::cccc or src host 2a06:d1c1:10d::aaaa or src host 2a09:ab81::91 or src host 2a12:d8c0:105a:9001::a154)'

sudo ip6tables -L INPUT -nv | grep -iE 'icmpv6|packet-too-big'
sudo nft list ruleset 2>/dev/null | grep -A1 'icmpv6'

sudo sysctl net.ipv6.conf.all.accept_redirects net.ipv4.ip_no_pmtu_disc net.ipv6.route.mtu_expires

sudo tcpdump -i any -n -e 'icmp6 and ip6[40] = 2 and (src host 2607:fae0:a000::42 or src host 2a00:8642:42::75 or src host 2a12:d8c0:105a:9001::a154 or src host 2a09:ab81::91 or src host 2a01:261:313:b814:2a0:98ff:fe5b:13e4 or src host 2a06:d1c1:10a::bbbb or src host 2a06:d1c1:10d::aaaa or src host 2a06:d1c1:10b::cccc)'

Multi-vantage path map

Every hop of all vantages’ traceroutes toward the target, drawn left→right, grouped into per-AS bubbles (a hop seen from several vantages is one shared bubble, so converging paths merge). It answers two questions per vantage — shown on each source bubble as echo ✓/⚠/✗ · trace ✓/✗: did the destination reply to ICMPv6 Echo (✓ honored, ⚠ replied but PTB not honored, ✗ no reply), and did the traceroute reach it. A line to the target is drawn only when that vantage got an echo reply — solid if the PTB was honored, dashed if not (reachable but a broken-PMTUD / RFC 4890 violation). The path depth still shows how far the traceroute itself got, and runs of unanswered (* *) hops collapse into one dashed “silent” bubble. Open full size ↗

• ● SRB host (SOX, Belgrade)
• ● DE host (Berlin)
• ● DE host (Düsseldorf)
• ● NL host (go6lab)
• ● ITA host (Karsolink)
• ● SLO host (6connect)
• ● SLO host (T-2)
• ── solid line = echo reply, PTB honored (clean reach)
• — — dashed line = echo reply but PTB not honored (RFC 4890 violation)
• no line = no echo reply (never reached)
• ◉ target: green = clean, amber = reachable-but-violation / unreachable
• ⚠ suspected drop AS
• ⋯ silent (unanswered) hops
• ● IXP hop

From SRB host (SOX, Belgrade)   openRFC 4890 ✗

filter likely at: (none) · min PMTU on path: 1500

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.009ms pmtu 1500
 1:  _gateway                                              0.462ms 
 1:  _gateway                                              1.074ms 
 2:  no reply
 3:  no reply
 4:  no reply
 5:  no reply
 6:  no reply
 7:  no reply
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From DE host (Berlin)   openRFC 4890 ✗

filter likely at: (none) · min PMTU on path: 1500

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.032ms pmtu 1500
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                 16.876ms 
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.381ms 
 2:  ae0-2453.cr10.ber01.lwlcom.net                        0.998ms 
 3:  retn.bcix.de                                         10.556ms asymm  5 
 4:  RT.TNR.BEG.RS.retn.net                               28.313ms asymm  5 
 5:  no reply
 6:  no reply
 7:  no reply
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From DE host (Düsseldorf)   openRFC 4890 ✗

filter likely at: (none) · min PMTU on path: 1500

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.021ms pmtu 1500
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.461ms 
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.298ms 
 2:  eth1-0-12-h5594.edge5-dus1.bb.wiit.network            1.235ms 
 3:  no reply
 4:  lag11.core3-dus1.bb.wiit.network                      0.435ms 
 5:  lag2.core2-dus3.bb.wiit.network                       0.261ms asymm  4 
 6:  lag0-vl1002.core1-ams-eq3.bb.wiit.network             3.708ms asymm  5 
 7:  no reply
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From NL host (go6lab)   openRFC 4890 ✗

filter likely at: (none) · min PMTU on path: 1500

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.039ms pmtu 1500
 1:  2a00:8642:42::2                                       5.739ms 
 1:  2a00:8642:42::2                                       4.335ms 
 2:  no reply
 3:  ccr2-ccr1.dc1.nogalliance.org                         3.665ms asymm  2 
 4:  no reply
 5:  no reply
 6:  no reply
 7:  no reply
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From ITA host (Karsolink)   echo onlyRFC 4890 ✗

filter likely at: destination AS15958 (CETIN_doo_AS) · min PMTU on path: 1500

Path (traceroute + mtr + PTR)

Rate-limited ICMPv6: hop 3 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.049ms pmtu 1500
 1:  karsolink-01.net.karsolink.com                        0.881ms 
 1:  karsolink-01.net.karsolink.com                        0.505ms 
 2:  2a12:d8c0:109f:121::a1                                0.661ms 
 3:  2a12:d8c0:109f:106::a2                                3.620ms 
 4:  ae8-202.rt.clr.mil.it.retn.net                        7.991ms asymm  5 
 5:  rt.tnr.beg.rs.retn.net                               19.572ms 
 6:  no reply
 7:  no reply
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From SLO host (6connect)   openRFC 4890 ✗

filter likely at: (none) · min PMTU on path: 1500

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.025ms pmtu 9000
 1:  fw1-lju.6connect.com                                  0.503ms 
 1:  fw1-lju.6connect.com                                  0.454ms 
 2:  ccr-to-fw-ccr1-gw-lju.6connect.com                    0.850ms 
 3:  2a03:a100:0:201:1::1                                  0.795ms 
 4:  2a03:a100:0:201:1::1                                  0.824ms pmtu 1500
 4:  e0-1.core1.lju1.he.net                                2.555ms 
 5:  100ge0-0-0-5.core1.vie1.he.net                        8.052ms 
 6:  e0-35.core2.bts1.he.net                               7.819ms 
 7:  no reply
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
     Too many hops: pmtu 1500

From SLO host (T-2)   openRFC 4890 ✓

filter likely at: (none) · min PMTU on path: 1500

Path (traceroute + mtr + PTR)

Rate-limited ICMPv6: hop 6 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.045ms pmtu 1500
 1:  2a01:261:313:b814::1                                  0.905ms 
 1:  2a01:261:313:b814::1                                  1.457ms 
 2:  2a01:260:1::225                                       3.524ms 
 3:  2a01-260-1-1--9a.core6.t-2.net                        2.881ms 
 4:  hurricane-electric.nikhef.nlsix.net                  35.760ms 
 5:  hurricane-electric.nikhef.nlsix.net                  40.549ms asymm  4 
 6:  be47.core3.ams1.he.net                               39.757ms 
 7:  be47.core3.ams1.he.net                               33.939ms asymm  6 
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500