Search found 1216 matches

by palinka
2019-11-20 23:11
Forum: General discussions
Topic: Database maintenance
Replies: 11
Views: 63

Re: Database maintenance

I think it makes more sense to migrate the database to mysql or other "real" database. No?
by palinka
2019-11-19 22:09
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Ok. Awesome. I will update the instructions. Thanks for the heads up.
by palinka
2019-11-19 16:25
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

The type [MySql.Data.MySqlClient.MySqlConnection] can not be found.

You said you re-downloaded the powershell file. Did you forget to change the database variables st the top? :D
by palinka
2019-11-18 23:28
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

and from the now created DBError.log (in parts): Der Typ [MySql.Data.MySqlClient.MySqlConnection] kann nicht gefunden werden. Stellen Sie sicher, dass die Assembly, die diesen Typ enthält, geladen wird. Es ist nicht möglich, eine Methode für einen Ausdruck aufzurufen, der den NULL hat. Der Typ [MyS...
by palinka
2019-11-18 21:08
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Arrrrggg! In the mysqlquery function, put the $ in front of DBError.log Missing the $.... you'd be up and running if it weren't for my typos. :lol: However, there must be a database error still, so when you get that sorted out, let me know what's actually in the error log. Edit No! Quotes are missin...
by palinka
2019-11-18 17:43
Forum: General discussions
Topic: Fake SURBL DNSBL from local network
Replies: 16
Views: 235

Re: Fake SURBL DNSBL from local network

You have corporate dns or Google dns? My computer is set to Google dns. The machine that hmailserver is on has Google or local dns? What happens when you do nslookup from that machine? It should not be different for hmailserver than for any other program on the server. Hmailserver is only using the...
by palinka
2019-11-18 05:29
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

I moved the table creation to the powershell script so it automatically created the tables.
by palinka
2019-11-18 01:48
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

And let me know when its working. :D
by palinka
2019-11-18 01:28
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Done - the hmailserver - part seems to be running now. At least there are currently no errors. I will have an eye on the logs. Now ... to the powershell - file. There are also some problems in it: D:\hMailServer\Addons\HMSFirewallBan\hmsFirewallBan.ps1 Es ist nicht möglich, eine Methode für einen A...
by palinka
2019-11-17 22:52
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Changed the code for FWBan with the one above and now there is another error: "SMTPD" "103.4.94.178" "RECEIVED: EHLO 103.4.94.178.pern.pk" "ERROR" "Severity: 2 (High), Code: HM5032, Source: DALConnection::Execute, Description: MySQL: Field 'ID' doesn't have a default value (Additional info: INSERT ...
by palinka
2019-11-17 14:57
Forum: General discussions
Topic: Refetch remaining POP3 Mails from external account
Replies: 7
Views: 100

Re: Refetch remaining POP3 Mails from external account

If you can access it by imap, you can log in to both accounts in Thunderbird and copy whatever you need from one account to the other.
by palinka
2019-11-17 12:01
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Call FWBan(oClient.IPAddress, "GeoIP", oClient.HELO) Function FWBan(sIPAddress, sReason) "ERROR" 652 "Script Error: Source: Runtime error in Microsoft VBScript - Error: 800A01C2 - Description: Wrong number of arguments or invalid property assignment: 'FWBan' - Line: 254 Column: 2 - Code: (null)" Ah...
by palinka
2019-11-17 01:54
Forum: Scripting
Topic: Mailbox Function Start Program
Replies: 3
Views: 85

Re: Mailbox Function Start Program

I wonder if this would work. It did not work for me, but I do not have any printer installed on my hmailserver machine. I did the cmd line portion from my laptop and it did work like a charm. https://superuser.com/questions/477895/printing-from-windows-7-command-line From the link, I worked out this...
by palinka
2019-11-17 00:49
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

I may have added this after you downloaded it. I made several changes today. It should go at the top of EventHandlers.vbs (below "option explicit", of course). ' COM authentication Private Const ADMIN = "Administrator" Private Const PASSWORD = "supersecretpassword" Private Const EVENTDIR = "C:\Prog...
by palinka
2019-11-16 23:05
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Hi, thx for your efforts. I deleted everything and started all over again with the latest version from github. Now another error is occuring: "ERROR" 3516 "Script Error: Source: Runtime error in Microsoft VBScript - Error: 800A01A8 - Description: Object required: 'LockFile(...)' - Line: 142 Column:...
by palinka
2019-11-16 18:15
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Try this to get country info into IDS: Function idsAddIP(sIPAddress) Include("C:\Program Files (x86)\hMailServer\Events\VbsJson.vbs") Dim ReturnCode, Json, oGeoip, oXML Set Json = New VbsJson On Error Resume Next Set oXML = CreateObject ("Msxml2.XMLHTTP.3.0") oXML.Open "GET", "http://ip-api.com/json...
by palinka
2019-11-16 17:05
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Line 261: Call FWBan(oClient.IPAddress, "HELO-Inv", oClient.HELO) Hmm - but "helo" is used in this function: Function idsAddIP(sIPAddress, sCountry, sHELO) Dim strSQL, oDB : Set oDB = GetDatabaseObject strSQL = "INSERT INTO hm_ids (timestamp,ipaddress,hits,country,helo) VALUES (NOW(),'" & sIPAddres...
by palinka
2019-11-16 15:47
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

hMailserver-User wrote:
2019-11-16 15:11
I still post my experience in setting this up - i hope you don't mind :-)
Absolutely. I haven't had a lot of feedback so yours is very helpful. I'm revising as you find things. So thank you for that.
by palinka
2019-11-16 15:35
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

I still post my experience in setting this up - i hope you don't mind :-) There is another line (114) which is using "idsTable". Changed it to hm_ids because in your project its not defined as variable. Another thing is that on the example for adding the three MSSQL tables on the hm_ids - table the...
by palinka
2019-11-16 14:28
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Also, you should check for updates often because most of the changes are in the web interface pages which you can just drop in without worrying about changes. Speaking of which, I just added a php version of BlockCount.ps1 to the web interface. Demo here: http://hmsfirewallbandemo.ddns.net/blocks.ph...
by palinka
2019-11-16 13:40
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

hi palinka, currently i'm running into another problem, error message: "ERROR" 2556 "2019-11-16 12:07:16.696" "Script Error: Source: Runtime error in Microsoft VBScript - Error: 800A01F4 - Description: Variable is not defined: 'idsTable' - Line: 107 Column: 4 - Code: (null)" referencing to (my) lin...
by palinka
2019-11-16 13:27
Forum: User-submitted tutorials
Topic: Hardening hMailServer - The ongoing saga!
Replies: 59
Views: 6741

Re: Hardening hMailServer - The ongoing saga!

Thank you, I appreciate this. I have one more question, how do I know if botnet has been banned? Is there a way I can check this? That depends on what you mean by ban. If you autoban rejections, then you can look in your ip ranges. If you firewall ban using my firewall ban project, there's a whole ...
by palinka
2019-11-15 20:07
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Hello palinka! trying to get things sorted with my hmailserver - installation so i downloades .48 from your GitHub Is it possible that in EventHandlers.vbs at line 180 a ' is missing? ("Exclude Backup-MX & local LAN from test" -> " ' Exclude Backup-MX & local LAN from test" at line 302 a ) is missi...
by palinka
2019-11-15 16:41
Forum: General discussions
Topic: Fake SURBL DNSBL from local network
Replies: 16
Views: 235

Re: Fake SURBL DNSBL from local network

Try changing to open DNS instead on the server. what? i already have corporate DNS on ip=192.168.0.12 tested: C:\Users\1>nslookup seal.com server: dns.google Address: 8.8.8.8 answer:  : seal.com Address: 174.129.25.170 You have corporate dns or Google dns? If it's Google DNS (which you reported in ...
by palinka
2019-11-15 15:12
Forum: Scripting
Topic: Mailbox Function Start Program
Replies: 3
Views: 85

Re: Mailbox Function Start Program

Since you have some kind of printer executable, it should be easy. Just call it the same way in eventhandlers.vbs. I looked around the documentation and it appears you can call the message filename.

https://www.hmailserver.com/documentati ... onsmtpdata
by palinka
2019-11-15 13:41
Forum: General discussions
Topic: Fake SURBL DNSBL from local network
Replies: 16
Views: 235

Re: Fake SURBL DNSBL from local network

Try changing to open DNS instead on the server.

I've read reports that firewalls can be hacked to fake dns queries.

http://www.rawinfopages.com/tips/2016/0 ... -settings/
by palinka
2019-11-13 14:05
Forum: Scripting
Topic: MaxMinds GeoIP for local MySQL
Replies: 18
Views: 914

Re: MaxMinds GeoIP for local MySQL

This week's update was a success. Everything worked and I got the email notification: GeoIP update start: 11/13/2019 1:30:01 AM 339,851 : (A) Records in database prior to update 5,809 : (B) Records removed from database 7,637 : (C) Records inserted into database ======= : 341,679 : Tabulated (A - B ...
by palinka
2019-11-13 13:37
Forum: General discussions
Topic: Autoban weirdness
Replies: 16
Views: 292

Re: Autoban weirdness

Has he also changed the default internet and Localhost rages Priority Only the 'My computer' range is higher, eg: 30 instead of the 15 it was before.... 'Internet' range is still 10 Nothing changed for me - meaning I upgraded and my old settings remained the same, but the new autoban = 100 was unkn...
by palinka
2019-11-13 00:53
Forum: General discussions
Topic: Autoban weirdness
Replies: 16
Views: 292

Re: Autoban weirdness

RvdH wrote:
2019-11-13 00:50
palinka wrote:
2019-11-13 00:47
I guess that's the answer. Problem solved.
I know :)
Some of us are a little slower... :lol:
by palinka
2019-11-13 00:47
Forum: General discussions
Topic: Autoban weirdness
Replies: 16
Views: 292

Re: Autoban weirdness

Autoban priority is changed in 5.7.x https://www.hmailserver.com/forum/viewtopic.php?f=7&t=34313 ONLY on the version used by that user ie Dravion's version hMailserver still sets them at 20 No, maybe your used scripts do, but hmailserver 5.7.x internally set them to 100 (eg: a faulty login via webm...
by palinka
2019-11-13 00:01
Forum: General discussions
Topic: Autoban weirdness
Replies: 16
Views: 292

Re: Autoban weirdness

For some reason, despite the priority elevation, 127.0.0.1 was denied access, therefore, my script was denied access and that Can you show logs of this happening please I will as soon as I get back to my computer, but they don't show anything other than "denied access due to ip range policy" or som...
by palinka
2019-11-12 23:18
Forum: General discussions
Topic: Autoban weirdness
Replies: 16
Views: 292

Re: Autoban weirdness

RvdH wrote:
2019-11-12 21:41
Autoban priority is changed in 5.7.x

https://www.hmailserver.com/forum/viewt ... =7&t=34313
Screenshot_20191112-161547_Brave.jpg

My autoban entries are being reported as priority 20. Are they actually 100? Is this a bug or a setup problem?
by palinka
2019-11-12 21:18
Forum: User contributed hMailServer 5 scripts
Topic: Check Service Status, Take Action, Notify
Replies: 5
Views: 1668

Re: Check Service Status, Take Action, Notify

Updated to cover a logic/sequence of events issue. $ErrorActionPreference = 'silentlycontinue' # USER VARIABLES $StartTime = (Get-Date 00:20) # check telnet start time - sometime after nightly backup ends $EndTime = (Get-Date 23:55) # check telnet end time - sometime before nightly backup begins $Ba...
by palinka
2019-11-12 16:17
Forum: General discussions
Topic: Autoban weirdness
Replies: 16
Views: 292

Autoban weirdness

Something strange happened last night. Its actually happened a couple of times before but this is the first time I investigated it. I run a script every 5 minutes to check telnet with the logic that if there is no response, something must be wrong and therefore, restart hmailserver service. That scr...
by palinka
2019-11-12 01:05
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

I re-ran the 40 day+ test with percentages. Its more readable, I think. I would say - completely arbitrarily - that 10% is a good number to look at. The 10% threshold is 4+ days, non-consecutively. What its not telling us is how many blocks are actually occurring. Its only counting IPs and the numbe...
by palinka
2019-11-12 00:32
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

20191111_172844.jpg
For example, this is the most recent block on the list - not the most recent to be blocked, but rather the most recent banned IP that was blocked (last drop in the firewall log). This one is kind of random. Not once per week, but nonetheless...
by palinka
2019-11-12 00:25
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

So just blocking for 14 days would catch most of them? No. They are not consecutive days. I counted distinct days. They could be consecutive, but experience shows they are not. Most are bots programmed for 5 hits per day, once per week. So a blocked IP that reappeared 14 times is likely to be once ...
by palinka
2019-11-11 20:45
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

I ran an experiment. How many IPs have returned and been blocked by the firewall for a given number of days? Lots. :D The "days" need not be consecutive. Some are, of course, but most are spread out once or twice a week. I only counted distinct days. Blocks are parsed from the firewall log. 12,810 :...
by palinka
2019-11-11 19:50
Forum: User-submitted tutorials
Topic: Hardening hMailServer - The ongoing saga!
Replies: 59
Views: 6741

Re: Hardening hMailServer - The ongoing saga!

Only check PTR on port 25. The logic behind that is only "real" mailservers should be connecting on port 25 and all of them should have a valid PTR. If you check the PTR on submission ports or IMAP/POP3 ports, you'll be checking all kinds of legitimate mail clients and nearly none will pass the no/d...
by palinka
2019-11-11 18:19
Forum: User-submitted tutorials
Topic: Hardening hMailServer - The ongoing saga!
Replies: 59
Views: 6741

Re: Hardening hMailServer - The ongoing saga!

Also, I just looked at my script and see that I did not strip out some of my custom stuff. This: If (oClient.Port = 25) Then If PTR_Record = "No.PTR.Record" Then Result.Value = 2 Result.Message = ". 03 Your access to this mail system has been rejected due to the sending MTA's poor reputation. If you...
by palinka
2019-11-11 18:14
Forum: User-submitted tutorials
Topic: Hardening hMailServer - The ongoing saga!
Replies: 59
Views: 6741

Re: Hardening hMailServer - The ongoing saga!

You probably don't have the disconnect function. Function Disconnect(sIPAddress) With CreateObject("WScript.Shell") .Run """C:\Program Files (x86)\hMailServer\Events\Disconnect.exe"" " & sIPAddress & "", 0, True REM EventLog.Write("Disconnect.exe " & sIPAddress & "") End With End Function You also n...
by palinka
2019-11-10 21:28
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Hello palinka, this would also work with version 5.6.8 of hMailserver? because according to GitHub version 5.7.0 of hMailserver is required. Thx! It will work with any version of hmailserver. However, one of the key features - recording the HELO greeting - requires either 5.7 or one of RvdH's custo...
by palinka
2019-11-10 04:19
Forum: General discussions
Topic: Cannot connect to mysql when setting bind-address=localhost
Replies: 10
Views: 368

Re: Cannot connect to mysql when setting bind-address=localhost

, today was the first time I've ever seen it :mrgreen: I've not ever seen it either Is that in the hmailserver.ini ? (hmailserver.ini doesn't get overwritten when you upgrade) Can someone please post the default 'hmailserver.ini' as it is currently created in a clean install It's in mysql my.ini, n...
by palinka
2019-11-10 03:07
Forum: General discussions
Topic: Cannot connect to mysql when setting bind-address=localhost
Replies: 10
Views: 368

Re: Cannot connect to mysql when setting bind-address=localhost

If I comment this line in my.ini ... Which line? # Change here for bind listening # bind-address="127.0.0.1" # bind-address = ::1 # for ipv6 I believe its commented out by default. By the documentation, it works exactly like the bind option in hmailserver. Binding to localhost should not allow any ...
by palinka
2019-11-09 23:43
Forum: General discussions
Topic: Cannot connect to mysql when setting bind-address=localhost
Replies: 10
Views: 368

Re: Cannot connect to mysql when setting bind-address=localhost

https://mariadb.com/kb/en/library/configuring-mariadb-for-remote-client-access/ bind-address requires a little bit of background information. A given server usually has at least two networking interfaces (although this is not required) and can easily have more. The two most common are a Loopback net...
by palinka
2019-11-09 04:24
Forum: Scripting
Topic: Pickup folder
Replies: 5
Views: 1507

Re: Pickup folder

I was poking around and saw this was never updated. Version below will authenticate and also use ssl. It can connect to any mail server now. Looks for NEW (not modified) files and emails them. Delete "-UseSsl" if you don't want encrypted connection. Powershell: ### Email Variables ##################...
by palinka
2019-11-07 13:34
Forum: Development & alpha discussions
Topic: DNS
Replies: 30
Views: 1136

Re: DNS

Well... Some of this gear is carrier grade and pretty damn expensive... https://tools.cisco.com/security/center/publicationListing.x Regarding firmware... xDSL residential customers in Denmark cannot use other equipment than the box provided by the ISP/ITSP. They can configure a DMZ and put their o...
by palinka
2019-11-07 02:25
Forum: Development & alpha discussions
Topic: DNS
Replies: 30
Views: 1136

Re: DNS

https://www.symantec.com/blogs/threat-intelligence/vpnfilter-iot-malware[quote] If you care about the security of your router, and you should, it is best to avoid consumer grade routers. On the whole, the software in these routers is buggy as heck. Personally, my opinion is that I wouldn't trust Sy...
by palinka
2019-11-05 04:23
Forum: General discussions
Topic: Where is treshold setting for SURBL filter?
Replies: 7
Views: 296

Re: Where is treshold setting for SURBL filter?

I guess I am missing something or I am dumb. I have problem with SURBL setting. Here is exception from log: "DEBUG" 4576 "2019-11-04 00:00:20.510" "SURBL: Execute" "DEBUG" 4576 "2019-11-04 00:00:20.510" "SURBL: Found URL: groups.io" "DEBUG" 4576 "2019-11-04 00:00:20.511" "SURBL: 1 unique addresses ...
by palinka
2019-11-05 02:11
Forum: Development & alpha discussions
Topic: DNS
Replies: 30
Views: 1136

Re: DNS

You could send me an email and have me click on it but that would be cheating and you hacking my network from the inside out ... Like how CIA/NSA and the Israeli infiltrated the Iranien nuclear power plants with Stuxnet ... That will only work once in my book :mrgreen: Didn't someone break in and p...
by palinka
2019-11-05 02:03
Forum: Development & alpha discussions
Topic: DNS
Replies: 30
Views: 1136

Re: DNS

mattg wrote:
2019-11-04 23:56
I get multiple IPs per day that try SMTP connections on my server via a custom port? How do they know which port and what service to try?
Firewall Ban those suckers!!! :mrgreen:

That's what I do.
by palinka
2019-11-04 17:47
Forum: General discussions
Topic: Configure internal server for email.
Replies: 34
Views: 1133

Re: Configure internal server for email.

is Horde Groupware Webmail compatable with outlook calender? also can we migrate existing appointments to the new system? Thanks. Yes. I connect outlook via activesync (a component in the horde framework). I think outlook can also connect via caldav, but activesync is a lot simpler with autodiscove...
by palinka
2019-11-04 17:35
Forum: General discussions
Topic: Where is treshold setting for SURBL filter?
Replies: 7
Views: 296

Re: Where is treshold setting for SURBL filter?

gmail sent the message successfully. "DEBUG" 10160 "2019-11-04 10:22:37.054" "SURBL: Execute" "DEBUG" 10160 "2019-11-04 10:22:37.054" "SURBL: Found URL: b99mon.com" "DEBUG" 10160 "2019-11-04 10:22:37.054" "SURBL: 1 unique addresses found." "DEBUG" 10160 "2019-11-04 10:22:37.070" "SURBL: Lookup: b99m...
by palinka
2019-11-04 17:05
Forum: General discussions
Topic: Where is treshold setting for SURBL filter?
Replies: 7
Views: 296

Re: Where is treshold setting for SURBL filter?

That's not correct palinka I think that the SURBL checks give a total score just for them after checking There was likely to be another score that isn't shown "DEBUG" 4576 "2019-11-04 00:00:20.511" "Spam test: SpamTestSURBL, Score: 4" "DEBUG" 4576 "2019-11-04 00:00:20.512" "Total spam score: 4" "SM...
by palinka
2019-11-04 15:11
Forum: General discussions
Topic: Where is treshold setting for SURBL filter?
Replies: 7
Views: 296

Re: Where is treshold setting for SURBL filter?

https://www.hmailserver.com/documentati ... urblserver

This is interesting. It appears that any hit on surbl causes rejection. Although the documentation is a little unclear. What's the point of scoring if it's going to be rejected no matter how high or low the score is?
by palinka
2019-11-04 14:54
Forum: General discussions
Topic: Configure internal server for email.
Replies: 34
Views: 1133

Re: Configure internal server for email.

Domain/DNS records - We currently host a windows exchange server managed by an external company. My concern is changing the DNS will result in the current email system not working. Is it possible to set up hamil in parralell to the exiting system? eventually transfering data to hmail and running hm...
by palinka
2019-11-04 14:49
Forum: General discussions
Topic: Configure internal server for email.
Replies: 34
Views: 1133

Re: Configure internal server for email.

There is no calendar/contact sync built into hMailServer. This means that - if using outlook as your mail client - all contact and calendars will be stored locally only. They will not be synced between devices (mobile, outlook, etc.). For this you will need some sort of groupware. I use Horde for th...
by palinka
2019-11-04 14:29
Forum: Scripting
Topic: Firewall Ban
Replies: 97
Views: 7142

Re: Firewall Ban

Screenshot_20191104-072024_Brave.jpg Here's how I know things are working well. Yesterday I cleaned up the blocks pages. One of the things I did was group blocks by day instead of a big giant list of individual hits. The information presented is more useful this way. Blocks are parsed from the fire...
by palinka
2019-11-02 04:18
Forum: General discussions
Topic: Configure internal server for email.
Replies: 34
Views: 1133

Re: Configure internal server for email.

Iam curious how manged to make hMailServer work in your own corporate Network without your own DNS-Server? Did you say to your Users "please insert the ip address joe@192.168.100.x"" or local Email will not work? My router handles dns in the simple way consumer routers do. I can call mydomain.tld f...
by palinka
2019-11-01 19:26
Forum: Scripting
Topic: oApplication.Stop hanging
Replies: 27
Views: 899

Re: oApplication.Stop hanging

http://infogalactic.com/info/SYN_cookies Drawbacks The use of SYN cookies does not break any protocol specifications, and therefore should be compatible with all TCP implementations. There are, however, two caveats that take effect when SYN cookies are in use. Firstly, the server is limited to only ...