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1. UNIX for Advanced & Expert Users
Hi guys, just need a opinion from you.
I found anti ddos script from github
Script
What is your opinion about it? Is it usefull? Do you have some similar? I want to protect my servers on all levels, why not in the servers via script.
I assume I must fix this script to be useful for me, but... (1 Reply)
Discussion started by: tomislav91
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2. Emergency UNIX and Linux Support
Dear community,
my site was recently attacjed by DDOS technique and goes down in a few minutes. My site runs under Debian/Apache2/Mysql.
I identified the IPs who attack me and block it through iptable firewall from debian.
Something like:
iptables -D INPUT -s xxx.xxx.xxx.xxx -j DROP
This... (7 Replies)
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I want to test the effectiveness of sshguard on some of my systems so I'm trying to write a script that simulates a brute force attack by sending a bunch of different username and password combinations to the servers being tested. So far I have this:
#!/usr/local/bin/expect
set timeout 3... (5 Replies)
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4. Cybersecurity
are there any popular DDoS simulation tools to test my own infrastructure? Anyone tried to setup all these in AWS EC2? (1 Reply)
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5. UNIX for Advanced & Expert Users
Im currently experiancing a brute force attack on my server
Nov 26 15:27:04 ws096 saslauthd: do_auth : auth failure:
Nov 26 15:27:13 ws096 saslauthd: do_auth : auth failure:
Nov 26 15:27:22 ws096 saslauthd: do_auth : auth failure:
Nov 26 15:27:29 ws096... (4 Replies)
Discussion started by: mcraul
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6. UNIX for Advanced & Expert Users
Hi,
I'm trying find out if there is a way to stop a brute force attack on a Webmail site. I'm trying to setup a webmail access, but I would like to prevent too many invalid logins from the same IP.
I've looked into Snort, but I was wondering if there was an application level firewall that can... (1 Reply)
Discussion started by: nitin
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7. Cybersecurity
heloo
today i have DDos Attack in my server
what is the better way to secure my server from DDos Attack
i use CentOS 4&5
i try every firewall and talk to softlayer - iweb i've Tried every possible solutions but I can not find a solution to the problems
Give Me The best way plzz (4 Replies)
Discussion started by: a7medo
4 Replies
LEARN ABOUT CENTOS
pam_fail_delay
PAM_FAIL_DELAY(3) Linux-PAM Manual PAM_FAIL_DELAY(3)
NAME
pam_fail_delay - request a delay on failure
SYNOPSIS
#include <security/pam_appl.h>
int pam_fail_delay(pam_handle_t *pamh, unsigned int usec);
DESCRIPTION
The pam_fail_delay function provides a mechanism by which an application or module can suggest a minimum delay of usec micro-seconds. The
function keeps a record of the longest time requested with this function. Should pam_authenticate(3) fail, the failing return to the
application is delayed by an amount of time randomly distributed (by up to 25%) about this longest value.
Independent of success, the delay time is reset to its zero default value when the PAM service module returns control to the application.
The delay occurs after all authentication modules have been called, but before control is returned to the service application.
When using this function the programmer should check if it is available with:
#ifdef HAVE_PAM_FAIL_DELAY
....
#endif /* HAVE_PAM_FAIL_DELAY */
For applications written with a single thread that are event driven in nature, generating this delay may be undesirable. Instead, the
application may want to register the delay in some other way. For example, in a single threaded server that serves multiple authentication
requests from a single event loop, the application might want to simply mark a given connection as blocked until an application timer
expires. For this reason the delay function can be changed with the PAM_FAIL_DELAY item. It can be queried and set with pam_get_item(3) and
pam_set_item (3) respectively. The value used to set it should be a function pointer of the following prototype:
void (*delay_fn)(int retval, unsigned usec_delay, void *appdata_ptr);
The arguments being the retval return code of the module stack, the usec_delay micro-second delay that libpam is requesting and the
appdata_ptr that the application has associated with the current pamh. This last value was set by the application when it called
pam_start(3) or explicitly with pam_set_item(3). Note, if PAM_FAIL_DELAY item is unset (or set to NULL), then no delay will be performed.
RATIONALE
It is often possible to attack an authentication scheme by exploiting the time it takes the scheme to deny access to an applicant user. In
cases of short timeouts, it may prove possible to attempt a brute force dictionary attack -- with an automated process, the attacker tries
all possible passwords to gain access to the system. In other cases, where individual failures can take measurable amounts of time
(indicating the nature of the failure), an attacker can obtain useful information about the authentication process. These latter attacks
make use of procedural delays that constitute a covert channel of useful information.
To minimize the effectiveness of such attacks, it is desirable to introduce a random delay in a failed authentication process. Preferable
this value should be set by the application or a special PAM module. Standard PAM modules should not modify the delay unconditional.
EXAMPLE
For example, a login application may require a failure delay of roughly 3 seconds. It will contain the following code:
pam_fail_delay (pamh, 3000000 /* micro-seconds */ );
pam_authenticate (pamh, 0);
if the modules do not request a delay, the failure delay will be between 2.25 and 3.75 seconds.
However, the modules, invoked in the authentication process, may also request delays:
module #1: pam_fail_delay (pamh, 2000000);
module #2: pam_fail_delay (pamh, 4000000);
in this case, it is the largest requested value that is used to compute the actual failed delay: here between 3 and 5 seconds.
RETURN VALUES
PAM_SUCCESS
Delay was successful adjusted.
PAM_SYSTEM_ERR
A NULL pointer was submitted as PAM handle.
SEE ALSO
pam_start(3), pam_get_item(3), pam_strerror(3)
STANDARDS
The pam_fail_delay function is an Linux-PAM extension.
Linux-PAM Manual 09/19/2013 PAM_FAIL_DELAY(3)