MoonPoint Support Logo


Shop Amazon Warehouse Deals - Deep Discounts on Open-box and Used ProductsAmazon Warehouse Deals

Advanced Search
Sun Mon Tue Wed Thu Fri Sat

Tue, Feb 21, 2017 11:21 pm

Dovecot not responding

A user reported that she wasn't receiving any email. When I logged into the mail servers, which runs Dovecot for POP3/POP3S and used Telnet to connect to port 110, the well-known port for POP3, I didn't get any response after I entered the user command, so I exited to the telnet prompt with Ctrl-].

$ telnet 110
Connected to
Escape character is '^]'.
user nell
telnet> quit
Connection closed.

I logged into the root account and checked today's and yesterday's maillog files for any references to Dovecot or POP3 issues, but saw none.

# grep -i dovecot /var/log/maillog
# grep -i dovecot /var/log/maillog.1
# grep -i pop3 /var/log/maillog.1
# grep -i pop3 /var/log/maillog

[ More Info ]

[/network/email/dovecot] permanent link

Tue, Feb 21, 2017 9:09 pm

Viewing the list of IP address ranges for AmazonAWS

If you need to create firewall rules for outgoing connectivity to Amazon Web Services (AWS) addresses, you can obtain a complete listing of the IP address ranges that Amazon uses in JavaScript Object Notation (JSON) format from AWS IP Ranges Are Now Available in JSON Format - the download URL for the file is

I downloaded the IP address range file from using cURL, which is present on Apple OS X/macOS systems and is available for Linux and many other operating systems, including Microsoft Windows - see Releases and Downloads.

$ curl -o ip-ranges.json
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   99k  100   99k    0     0   191k      0 --:--:-- --:--:-- --:--:--  191k

The following Python script can be used to extract just the Classless Inter-Domain Routing (CIDR) address blocks, i.e., the ip_prefix information from the JSON data stored in the ip-ranges.json file downloaded from the Amazon website and display it.

import json

data = json.load(open('ip-ranges.json'))
for d in data["prefixes"]:
    print d["ip_prefix"]

[ More Info ]

[/languages/python] permanent link

Valid HTML 4.01 Transitional

Privacy Policy   Contact

Blosxom logo