- Virtual Machine: Ubuntu 14.04.1 LTS
- I'm using putty to access Ubuntu from my Windows 7 PC.
- This Ubuntu machine does not have a registered domain name.
- Setting up a local SMTP server on this Ubuntu VM requires a full MTA which requires a registered domain name, which isn't going to happen.
- On the Ubuntu VM I'm using the Google name servers of 126.96.36.199 and 188.8.131.52.
- For old SMTPServer1, there is a limit if about 100 outgoing emails per day per account/username, and I'm the only one who uses this SMTP username and I don't generate 250 emails every day. I do about 25-30 max on certain days.
- I'm using Perl 5.18.2 to talk directly to the SMTP server, so I don't need an MTA.
- On my Ubuntu VM, doing
nslookup email.abc.comgives me a non-authoritative IP address of the correct IP for the new SMTP server, which is, say 184.108.40.206.
This Ubuntu VM runs on our network and I've been making reports and sending outbound email only via SMTPServer1 for a while now. SMTPServer1 has poor service so I'm changing SMTP servers to an SMTP server internal to our network, something our company runs. When I try to test my connection from Ubuntu to the new SMTP server, I telnet in to the name like this:
telnet email.abc.com 2525 because we use a non-standard port for SMTP.
What I get every time is
"Trying email.abc.com..." and it just hangs there until I get a timeout error. The same thing happens when I try to telnet directly to the IP address. The other guy running the new (to me) SMTP server claims it's open for my IP of the Ubuntu server and his SMTP server is running.
- First, what do I need to check? I'm on my own here, IT doesn't know anything about Ubuntu.
- How do I set up my machine, and/or DNS, to access the new SMTP server? I already know how to set up my Perl program to do it, but my test is not working, hence my question.
EDIT: I just added our internal DNS servers to
/etc/network/interfaces. The first 2 entries for
dns-nameservers are 10.19.* and they are our internal DNS servers. The next 2 entries are Google DNS servers, the last is a OpenDNS server. It now looks like this:
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
iface lo inet loopback
# The primary network interface
iface eth0 inet static
dns-nameservers 10.19.1.66 10.19.1.67 220.127.116.11 18.104.22.168 22.214.171.124
# See /home/chuck/perl/stuff/setiptable.
pre-up iptables-restore < /etc/iptables/rules.v4
After the edit (using sudo nedit /etc/network/interfaces) I did:
sudo service network-manager restart.
I also edited
sudo /etc/resolvconf/resolv.conf.d/base which now has our 2 internal DNS servers first, followed by 2 Google DNS servers, and it now looks like this:
After editing I did
sudo resolvconf -u.
So then I did ping and nmap. Ping works. Nmap returns this. If someone could help me decipher the nmap output, then I can learn. I don't mind learning. But I'm new at this part. Everyone is at one point.
Starting Nmap 6.40 ( http://nmap.org ) at 2015-06-23 06:39 EDT
Nmap scan report for email.abc.com (126.96.36.199)
Host is up.
rDNS record for 188.8.131.52: acmkokisco.gs01.gridserver.com
PORT STATE SERVICE
2525/tcp filtered ms-v-worlds
Nmap done: 1 IP address (1 host up) scanned in 2.12 seconds
If I'm doing nmap from my Ubuntu server to the SMTP server, why does it say "filtered"? Did the guy running the SMTP server not allow my Ubuntu IP correctly? I know when you make changes to Ubuntu you sometimes have to restart services. I wonder if he didn't restart the service correctly. I am trying to figure out what to tell him, i.e. if the problem is at my end or his.
Non-authoritative answer: Name: email.abc.com Address: 184.108.40.206
Doesn't this mean it used the 220.127.116.11 (Google) DNS server to get the IP?
10.19.3.13 is the IP of my Ubuntu machine, and I'm trying to access the SMTP server from there. Output of
$ tcptraceroute email.abc.com 2525
Selected device eth0, address 10.19.3.13, port 57049 for outgoing packets
Tracing the path to email.abc.com (18.104.22.168) on TCP port 2525, 30 hops max
1 * * *
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30 * * *
Destination not reached
sudo apt-get install nmap, then
nmap -sS -P0 -p 2525 email.abc.com. If it returns the state as "filtered", there's likely a firewall in the way (or you're not in an IP allowed email server config). It should return the state as "open".