AS5 ipv6 hijack?

Anyone from AS5 here?
I see ipv6 bgp hijack of our prefixes via AS5.

Seen from PCCW perspective only, maybe somebody from PCCW can help?


Dmitry Sherman <> writes:

I see ipv6 bgp hijack of our prefixes via AS5.

Or misunderstood prepending attempt, like hijacks from low AS numbers
often are?


OK, so that email bounced. Or will eventually because this does not go
away with someone doing something:

  <>... Deferred: 403 4.7.0 TLS handshake failed.

I am posting this in public because it unfortunately is a very common

Debian buster was released on July 6th, 2019. It includes openssl 1.1.1
with this configuration update among number of other improvements:

openssl (1.1.1~~pre6-1) experimental; urgency=medium

  * New upstream version
  * Increase default security level from 1 to 2. This moves from the 80 bit
    security level to the 112 bit securit level and will require 2048 bit RSA
    and DHE keys.

-- Kurt Roeckx <> Tue, 01 May 2018 16:00:55 +0200

I assume similar policies have been applied to all modern and maintained
operating systems by now.

Everyone should verify their own SMTP servers to avoid losing email due
to TLS failures. Doing so is simple from e.g Debian:

bjorn@canardo:/usr/local/src/openwrt$ cd
bjorn@canardo:~$ host has address mail is handled by 10

bjorn@canardo:~$ openssl s_client -quiet -connect -starttls smtp
depth=2 C = US, O = DigiCert Inc, OU =, CN = DigiCert Global Root CA
verify return:1
depth=1 C = US, O = DigiCert Inc, OU =, CN = RapidSSL RSA CA 2018
verify return:1
depth=0 CN = *
verify return:1
139901908640896:error:141A318A:SSL routines:tls_process_ske_dhe:dh key too small:../ssl/statem/statem_clnt.c:2150:

The fix obviously depends on the server, but is usually as simple as
regnerating the DH parameters. See for example


A slightly nicer tool than just using "openssl s_client" is,
handles STARTTLS and some other non-trivial cases.

Back when I first used it I did read the source, these days at ~650k of
shell script, that's a little less practical.