Does the Asus RT-AC66U require ICMP for anything

As mentioned in a prior post I am having a problem connecting to
Verizon'a mail servers. In researching this I find I get as far as the
gateway to Verizon's internal servers but no further. I was told the
next server is probably blocking ICMP.

I can ping smtp.1and1.com but not smtp.verizon.net.

I can connect to Verizon's mail servers with my old Linksys router but
not with the Asus.

The Asus seems to do everything else with zero problems. It just won't
let me connect to verizon mail.

I can't see why blocking ICMP should be an issue unless the Asus somehow
requires it in the process of trying to connect to Verizon's servers.

 

That's a fair assumption. For the most part, I suggested traceroute to
verify that the connection attempt isn't dying at your router, on the way
out.

Same behavior here, but I can telnet equally well to both of them on port
465. I don't have login credentials, so my experiment ends there.

What if you change the order of the list of email accounts, or if you add a
dummy account to the end of the list? If that works, it rules out the
router.

Some admins disable ICMP replies. It doesn't mean anything more than that.

I mentioned it before, but I'll bring it up again. If you have access to a
packet capture utility and know how to use it, you can track the problem
down that way. Wireshark for the PC comes to mind, but I think you mentioned
Mac, so I'm not sure what you have available.

Google to the rescue: https://www.wireshark.org/download.html
Looks like Mac may be supported after all.

 

I just tried to post a reply and it didn't go! I will try again if I
can remember what I said before.

Telnet smtp.verizon.net 465 times out for me, probably because I am
being blocked by an intermediate server.

I cannot seem to do either.

I am at a loss as to how to re-order the list and it may not even be
possible. It seems to be kept in alphabetical order, which would make
it tough to come up with something below Verizon!

I cannot create a fictitious account because mail checks it before
creating it. Trying to create a duplicate doesn't seem to do anything.

An extra account below Verizon would be an interesting way to see if the
router is doing something.

I don't have one and have never used one so it probably wouldn't help me
much. The only reason I could use traceroute and telnet was I have used
them before and just had to refresh my memory from the man pages.

 

No worries. I'm just about out of ideas. Circling back to DNS for a moment,
it's possible that the two routers are configured to use different DNS
servers, and it's possible that you have your computers configured to use
whatever the router is using. If both of those conditions are true, one of
the two DNS servers could be resolving smtp.verizon.net to the wrong IP
address, but that doesn't help to explain anything regarding the list of
mail servers and the odd behavior by the one that happens to be last in the
list.

It's also possible that there are two issues in play because one part of the
problem description does point to the router (you swap it and the problem
goes away) while the other part of the problem description clearly points to
the computers (last email server in the list).

For me, smtp.verizon.net resolves to this:

Server: google-public-dns-a.google.com
Address: 8.8.8.8

Name: smtp.verizon.net
Address: 206.46.232.100


If you get something different on the computer that can't connect, try
changing your DNS server and see if you get a different answer.

 

It turns out to be worse than that. My IP was causing the problem but
it did it gradually instead of instantly. Initially I could use my
Linksys router, a direct connection to the modem or an unprotected WiFi
network in the area but not my Asus router. Eventually I could not
connect on anything but the local hotel network.

The WiFi network in a nearby hotel worked fine because it was on a
different block of addresses. When I got my ISP to move me to a
different block the problem went away.

What I can't figure out is why this happened gradually. If my address
was being blacklisted I think it should have just turned off. The
gradual fade led my down many blind alleys I could have avoided.

 

That's an interesting final twist to the story. Thanks for sharing, and good
luck going forward.