Invalid method in request \x16\x03\x01

hansbjarstal · 09-05-2014, 08:19 AM

Hi. I am not sure is this is a security issue or not, but anyhow, I post it here. the error.log for Apache 2 on Debian 6 shows "Invalid method in request \x16\x03\x01" repeatedly from 3 diffrent IP addresses. Then I found a pattern: 2 of the addresses are where my wife connects: at her workplace and in our home, and as long her computer is up running I have this message on the server. Yesterday it was exactly every 5 minutes but today the pattern is little different: There are 2 notes on exactly the same second and then there are 6 to 9 minutes to the next. The 3d IP address is to my own office and as long my office computer is up running the message is comming up in the log very frequently. NOTE; it is only from thsese 3 addresses. Does any one have any idea what it could be? I am quite noew on Debian and Linux.

unSpawn · 09-05-2014, 08:40 AM

Could https://www.linuxquestions.org/quest...centos-901115/ or https://www.linuxquestions.org/quest...01-4175456839/ help you shed a light on things? ;-p

hansbjarstal · 09-14-2014, 10:41 AM

Quote:

Originally Posted by unSpawn

Could https://www.linuxquestions.org/quest...centos-901115/ or https://www.linuxquestions.org/quest...01-4175456839/ help you shed a light on things? ;-p

Thank you UNspawn, I've seen these earlier but I don not understand why my and my wives computers are making freqvent calls to the server as soon as they are connected to the internet. Any idea about that?

unSpawn · 09-15-2014, 01:31 AM

Your follow up question was not a Linux Security question so I've moved it to its own thread here: https://www.linuxquestions.org/quest...ls-4175518778/

unSpawn · 09-15-2014, 01:35 AM

Quote:

Originally Posted by hansbjarstal

I don not understand why

Do these machines send any other requests to the web server? If yes, what are they asking for? Else what happens if you block the request? (You might want to choose your personal machine as guinea pig.)

hansbjarstal · 09-15-2014, 03:33 AM

Quote:

Do these machines send any other requests to the web server?

I cannot see any other requests.

Quote:

Else what happens if you block the request?

Hmm.., as I said, I'm a newbe. How do I block the request ?

unSpawn · 09-15-2014, 12:19 PM

Quote:

Originally Posted by hansbjarstal

How do I block the request ?

Post 'iptables-save' output (obfuscate your IP address if necessary) and we'll tell you where to add which rule, no problem.

hansbjarstal · 09-15-2014, 12:31 PM

Quote:

Post 'iptables-save' output (obfuscate your IP address if necessary) and we'll tell you where to add which rule, no problem.

Below this there are a few houndred lines of blocking China and some ohter countries. I didn't take that with, just the first line.

Code:

> iptables-save
# Generated by iptables-save v1.4.8 on Mon Sep 15 19:21:29 2014
*nat
:PREROUTING ACCEPT [2435:171982]
:POSTROUTING ACCEPT [3492:218124]
:OUTPUT ACCEPT [3492:218124]
COMMIT
# Completed on Mon Sep 15 19:21:29 2014
# Generated by iptables-save v1.4.8 on Mon Sep 15 19:21:29 2014
*mangle
:PREROUTING ACCEPT [106274:58222645]
:INPUT ACCEPT [106274:58222645]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [85240:111032439]
:POSTROUTING ACCEPT [85240:111032439]
COMMIT
# Completed on Mon Sep 15 19:21:29 2014
# Generated by iptables-save v1.4.8 on Mon Sep 15 19:21:29 2014
*filter
:INPUT ACCEPT [46214:49280372]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [85240:111032439]
-A INPUT -s 1.0.1.0/24 -j DROP

unSpawn · 09-15-2014, 01:34 PM

Sorry, I meant 'iptables-save' of your own office computer. (Less harm in breaking that compared to breaking a server.)

hansbjarstal · 09-15-2014, 01:48 PM

Quote:

Originally Posted by unSpawn

Sorry, I meant 'iptables-save' of your own office computer. (Less harm in breaking that compared to breaking a server.)

Hmm... It is a Windows 7.(By the way, I can't risk to mess this computer up either.)

Shall I make a setting in the Windows Firewall?

unSpawn · 09-15-2014, 01:51 PM

Yes, that would be best. Just block only the combination of specific outbound IP address of the server and port TCP/80. Ah, and since it's Windows it never hurts to run an antivirus / malware check.

hansbjarstal · 09-15-2014, 03:18 PM

Quote:

Originally Posted by unSpawn

Ah, and since it's Windows it never hurts to run an antivirus / malware check.

I'm running anti-virus scan every night and I use Malwarebytes Anti-Malware regulary.

Quote:

Yes, that would be best. Just block only the combination of specific outbound IP address of the server and port TCP/80.

If I got you right I shall in Windows Firewall on by office computer block the remote port TCP 80 on the IP address of the server?

I did so but it keeps on, every 5 minutes as you can see in the Apache error log below

Code:

[Mon Sep 15 20:39:51 2014] [error] [client xx.166.231.xx] Invalid method in request \x16\x03\x01
[Mon Sep 15 20:44:40 2014] [error] [client xx.166.231.xx] Invalid method in request \x16\x03\x01
[Mon Sep 15 20:49:42 2014] [error] [client xx.166.231.xx] Invalid method in request \x16\x03\x01
[Mon Sep 15 20:54:45 2014] [error] [client xx.166.231.xx] Invalid method in request \x16\x03\x01
[Mon Sep 15 20:59:48 2014] [error] [client xx.166.231.xx] Invalid method in request \x16\x03\x01
[Mon Sep 15 21:04:51 2014] [error] [client xx.166.231.xx] Invalid method in request \x16\x03\x01
[Mon Sep 15 21:09:54 2014] [error] [client xx.166.231.xx] Invalid method in request \x16\x03\x01

unSpawn · 09-17-2014, 03:42 PM

Quote:

Originally Posted by hansbjarstal

I did so but it keeps on, every 5 minutes as you can see

Hmm. Lets try another approach. Do cut me some slack because I don't have a Windows PC at hand so I have to do this from memory. Basically what you could do is load either Nirsoft "netstat" (or whatever its called) as it should give you Process Ids as well as remote addresses, IIRC you can even filter for IP address and port, to help you identify the process or Sysinternals Process Explorer.