A blacklist is a basic access control mechanism that rejects elements included in the list.

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21
votes
12answers
29k views

Which anti spam DNS blacklists should used?

i want to protect my mailserver with dns blacklists for fighting the spam. there a so many blacklists out there. currently i use: ix.dnsbl.manitu.net cbl.abuseat.org bl.spamcop.net safe.dnsbl.sorbs....
20
votes
4answers
2k views

What are the best methods for catching snowshoe spam?

I'm using Smartermail for my small mailserver. We've been having a problem lately of getting waves of snowshoe spam that follow the same pattern. They come in batches of 3 or 4 at a time. The ...
19
votes
6answers
8k views

Use IPtables or null route for blacklisting about 1 million IP addresses?

I've come across a situation where a client needs to blacklist a set of just under 1 million individual IP addresses (no subnets), and network performance is a concern. While I would conjecture that ...
15
votes
5answers
45k views

Whitelist allowed IPs (in/out) using iptables

I have a few ip ranges to which I want my server to able to connect and users to connect from. Everything else should be blocked. How should I do that with iptables? My OS is Debian based linux ...
12
votes
10answers
5k views

Where to go to see if my IP is blacklisted as a SPAM

This has happened before and some mail servers will tell you that your IP has been blacklisted (RBL, CBL, etc) but I can't find that site to check anymore and searches result in a site that may or may ...
12
votes
3answers
882 views

How to remove ourselves from nudity blacklists? [duplicate]

We recently bought our domain. It turns out, two generations ago, it was a porn site. Now we're still blocked in some filters, resulting in blocked pages at several corporate routers. I'm now ...
11
votes
7answers
4k views

Check public DNS health and RFC compliance

Every now and again I like to run checks on my DNS servers to make sure they are running right and to RFC spec. I used to use the DNSTools website to do this as it gave me a pretty good picture of ...
7
votes
2answers
2k views

Getting a domain name off of the blacklist

I have a friend who purchased a domain name recently that he found out (after buying it) is apparently blocked by many corporate firewalls or proxies b/c it's been tagged as porn by the blacklist db ...
7
votes
4answers
13k views

How to report spam to blacklists

Is there a central place to report spam to various blacklists ? I regularly report to spamcop, but I do not see the addresses I reported as listed. (I guess nobody else bothers with my regular ...
6
votes
2answers
20k views

Why is my email server in AT&T's blacklist?

I just got this bounce message: <████████@att.net>: host scc-mailrelay.att.net[204.127.208.75] said: 521-88.208.246.34 blocked by sbc:blacklist.mailrelay.att.net. 521 DNSRBL: Blocked ...
6
votes
2answers
325 views

Which DNS Black Lists would you recommend to discard spam in pre-queue?

There are many black lists out there, with bad and good reputations. Also, some people recommend to use RBL lists only in score-based systems (like spamassassin) while others (including commercial ...
5
votes
2answers
5k views

Refuse to send email to specific recipients with Postfix

So, right now I am halfway through trying to setup an outgoing-mail blacklist, by way of smtpd_recipient_restrictions. The problem I am experiencing is that my test emails are being delivered when I ...
4
votes
5answers
4k views

Best way to use large IP blacklist to deny access to a web server?

Is there efficient and easy way to use IP blacklist (like this one, but perhaps 2-3 times larger, which can't be simplified to CIDRs much) to deny access to a web server (either lighttpd or Apache) ...
4
votes
5answers
17k views

How do I get my server off the ivmSIP/24 blacklist?

I checked my server IP using this tool: http://www.mxtoolbox.com/SuperTool.aspx It's come up on the ivmSIP/24 list. What can I do to get my IP removed from this list? I have SPF records set to ...
4
votes
3answers
849 views

Customer's IP Listed on RBL - What steps do you use to prevent black listing?

Customer called saying their e-mail was bouncing from particular vendors. Investigated it and identified they were listed on more than one RBL/CBL. Restricted firewall to only allow traffic on port ...
4
votes
2answers
10k views

Gmail.com detect mail as spam, but the server is not on any BlackList

I have an issue with Google. (GMail to be exact) About 1 month ago, we had a security breach, and mail was relayed through our servers. we got listed in almost ALL Black-Lists :( we fixed the ...
4
votes
1answer
573 views

How to blacklist or whitelist lots or few ip ranges with ipset and iptables + fail2ban

EDIT: It's astonishing how the urge to find a solution sometimes is sufficient to slowly but steadily lead one towards a solution. Also, the more often I reread my question in order to clarify it, I ...
3
votes
2answers
10k views

Blocking apache access via user agent string

I've got a scripter who is using a proxy to attack a website I'm serving. I've noticed that they tend to access the site via software with a certain common user agent string (i.e. http://www....
3
votes
2answers
4k views

Where to place Nginx IP blacklist config file?

I have an Nginx web server hosting two sites. I created a blockips.conf file to blacklist IP addresses that are constantly probing the server and included this file in the nginx.conf file. However ...
3
votes
2answers
3k views

hotmail blacklist and rDNS questions

My company has recently purchased a VPS for email and webhosting. I am not an expert on email authentication but here is my story. After the VPS was purchased we started receiving bouncebacks with ...
3
votes
3answers
1k views

How do I prevent mail from my Exchange server from being blocked?

Recently one of our client machines was infected with a virus and I believe was spamming addresses in the user's contact list. Since then our server has been appearing on blacklists and it has been ...
3
votes
2answers
95 views

SMTP: Which IP should I monitor?

I use a relay server to deliver external mails. I use relay server's IP in SPF record. But I'm not sure about blacklist monitoring/checking. Should I check main server's IP or relay's IP?
3
votes
2answers
2k views

Unable to delist from SORBS blacklist [closed]

The IP address of one of my servers has been blacklisted by SORBS. The delisting process on their website does not work correctly for me. Asides from contacting SORBS directly, is there anything ...
3
votes
2answers
6k views

CBL This IP address is HELO'ing as “localhost.localdomain”

I am pretty lost here, my server somehow got into a blacklist. And I don't know why and how to solve it. Please take a look at the link below. CBL List - click here Anyone knows what is going on ...
3
votes
3answers
3k views

Postfix restrict recipients

how can I configure postfix to allow sending to a certain (external) domain only? I'm already using check_recipient_access. Content of my /etc/postfix/recipients_restrictions: domain.com OK My (...
3
votes
6answers
2k views

How to check, if IPs in your network are blacklisted?

I would like actively monitor, if any of my network IPs are on blacklists. Here I would like to collect links to instructions, how to sync blacklists, which allows that.
3
votes
1answer
154 views

Postfix reject_rbl_client Blacklists Not Working

I have a mail server (iRedMail) that uses Postfix. I've been getting a lot of spam, so I modified the /etc/postfix/main.cf file and have the smtpd_recipient_restrictions set to this: ...
2
votes
5answers
1k views

Blacklisting: IP's or domains?

I am implementing a blacklisting system on my website that monitors contact forms for suspicious usage (both spam content and excessive frequency). When I find somebody / robot that meets my criteria ...
2
votes
6answers
741 views

Eliminate Email Blacklist by switching IPs and Servers

We are a legitimate company. We have had some issues in the past with Virus attacks/ Spam bots getting our email server blacklisted. After the most recent attack I have been tasked at coming up with ...
2
votes
4answers
554 views

False IP blacklisting on CBL and Spamhaus ZEN

I've gone thru this: Spamhaus XBL keeps adding my IP I'm managing the server 23.239.30.81 on Ubuntu using Postfix. Since last 6 months or so I started forwarding all my: Cron Daemon logs ...
2
votes
2answers
54 views

Are only IP-Addresses Blacklisted or also Domains?

Unfortunately one of the forms of my website was used to send completely sensless spammails. As I found out through "http://mxtoolbox.com" that my IP-address is listed on two blacklists, I want to set ...
2
votes
3answers
7k views

Email Server IP Address is Blacklisted

we have a Zimbra Mail server that was being used for 2 months now. the last week we faced a problem that the Public IP that was being used for our mail server started to be blacklisted and we couldn't ...
2
votes
4answers
972 views

Best practices on how to send emails on clients behalf and avoid being black listed

I am starting a business providing some online customer relationship management functionality. I want to allow my clients to create their own email lists. I also want to allow my clients to be able ...
2
votes
2answers
1k views

Can I create a website blacklist with Group Policy?

I can create "whitelist" functionality for blocking all sites and allowing some via the GP setting: User Configuration > Windows Settings > Internet Explorer Maintenance > Connection/Proxy ...
2
votes
1answer
61 views

Spamassassin: Bypass /etc/resolv.conf DNS for querying DNSBL?

Question Is there a way to let spamassassin bypass my linux system's dns servers to query DNSBLs? Background Info When my Server receives email, it is checked by spamassassin. One of this checks ...
2
votes
1answer
148 views

Postfix thinks IP is in blacklist, but is not actually listed in blacklist

Got a bit of a weird problem here with Postfix. Been getting a whole bunch of notices where fail2ban has banned 69.164.196.21 (ryujin.darkdna.net) for failures against Postfix. Here is a relevant ...
2
votes
1answer
252 views

How do I implement IP-based export restrictions for my data stored on Amazon S3?

A little background: Corporate wants to make our downloads unavailable to U.S. export-restricted countries like North Korea, Iran, Syria, etc. Restriction by IP-block is considered good enough. (Yes, ...
2
votes
1answer
200 views

Will using google apps emailhosting get rid of blacklisting caused by a shared server account?

a client`s email addresses are constantly blacklisted due to other users who share the same server. the hoster does want him to switch to his own dedicated server, so he gets his own ip. my question ...
2
votes
1answer
523 views

How does IP blacklisting work on virtualized/shared hosting?

I have read that many blocks of IP addresses associated with Amazon EC2 have been blacklisted by various ISPs. Therefore, even if you never sent spam yourself, emails you send from an Amazon instance ...
2
votes
1answer
595 views

how to specify a partial domain in blacklist with SpamAssassin

is there a way to specify a partial domain in the spamassassin blacklist? I get spam from something like abc@something1.something2.xyz but I also get junk from abc@something3.xyz. if I specify @.xyz ...
2
votes
1answer
791 views

Postfix: Resend 'hard' bounces

I had a number of messages get rejected by the recipient's mail server with a status 550 code due to an IP address blacklist. I've sorted the problem that caused the host to become blacklisted, and ...
2
votes
1answer
669 views

How to whitelist CloudFlare IP ranges within iptables rules (multiport)?

There seem to be many different ways to setup whitelist rules within iptables. What is the wisest way to whitelist the CloudFlare IP address ranges below via SSH? 204.93.240.0/24 (204.93.240.0 - 204....
2
votes
3answers
264 views

Reporting Suspicious Traffic

Is anyone aware of a web service that allows people to publish ip addresses as having run vulnerability scanning tools to determine the signature of the target? I would like to have a scheduled job ...
2
votes
1answer
123 views

at what level modprobe operates ? - linux

I have a machine with Ubuntu 12.04 64 bit, i have the need for blacklisting a module, i have blacklisted it in blacklist.conf but nothing happened; i have solved my problem passing modprobe.blacklist=&...
2
votes
4answers
4k views

Where to find and how to block blacklisted IPs and proxies?

Good day everyone! I'm looking for a way to block incoming requests from blacklisted IPs and proxies (mostly anonymous) to my server. While it's quite obvious how to do it using Apache config the ...
2
votes
2answers
12k views

How to unblacklist an IP at Google?

I own a small business with two servers for webhosting. When setting up the primary (CentOS 5.5 + WHM, secondary is WHM DNS Only) server I kinda messed up the firewall, so the hackers could send stuff ...
2
votes
2answers
2k views

Blacklist preventing DNS lookups?

To make a long story short, some users at another company who I have a lot of email correspondence with started having problems sending me email, they would get a message from the mailer daemon at ...
1
vote
5answers
326 views

IP address blacklisting program

Are there any IP address blacklisting programs for Linux servers that allow the administrator to specify certain conditions that trigger an iptables blacklist on IP addresses scanning for ...
1
vote
5answers
148 views

Mail server blacklists

Recently I've had a few clients on a server having issues with a blacklist. I've been googling for about an hour and am a little tired of it, but maybe someone here can help me. What do blacklists ...
1
vote
2answers
740 views

Mac server infected with spam agent

We have a huge trouble :( .. Our mac server makes a spam delivery. Our IP already blacklisted in about a dozen of servers (checked with http://mxtoolbox.com/). We have another computers in the same ...