[RndTbl] Shaw blocking port 25 on business line

Trevor Cordes trevor at tecnopolis.ca
Tue Feb 11 16:18:40 CST 2020

On 2020-02-05 Gerald Brandt wrote:
> I have no problem having a tech in here. When they lost my multihome 
> config, I had a tech on-site for 4.5 hours before it was resolved.

Multihome?  Make sure your telnet tests are going out over the
interface you are thinking they are... I would possibly disable/unplug
the 2nd route out so you're absolutely positive you are testing the
Shaw path when you run your tests.

I fully trust that what you are saying is correct, and I'm very sure
the problem is on Shaw's side, but it's prudent to make sure you're not
overlooking something on the periphery.

> Reverse DNS is correct, DHCP is disabled... Shaw sees me pulling my 
> "static" IPs.

That's odd.  Might just be the terminology, but when you setup a static
IP, your ISP cannot see you "pull" anything.  There is no pulling.
Maybe you (or Shaw) just worded it weirdly.

The only way Shaw "seeing" you "pull" a "static" is if they have you
use DHCP but have your MAC assigned to a static IP in their DHCP
server.  I'm not sure Shaw ever does that.

Of course, you can confirm definitively if any DHCP is going on by
tcpdump -i <interface> ... on port 67/68 udp then unplug and replug
your lan cable and/or power cycle your modem.

Keep in mind that in modern Linuxes, NetworkManager pervasiveness makes
it very hard to be 100% positive the network is behaving as you expect.
So much so that on router/firewall boxes of mine I fight very hard to
make sure it's disabled and stays that way.  However, old-style net
configs are deprecated and we're all supposed to use nm and nm-cli
going forward (probably by the next Fedora).  Sigh.

More information about the Roundtable mailing list