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Today's Topics:
1. Securing SSH --> Change ports (Theodor Sigurjon Andresson)
2. Re: Securing SSH --> Change ports (Karsten Wade)
3. Re: Securing SSH --> Change ports (Theodor Sigurjon Andresson)
4. Re: Securing SSH --> Change ports (PJ Welsh)
5. Re: Securing SSH --> Change ports (Theodor Sigurjon Andresson)
6. Re: Securing SSH --> Change ports (Manuel Wolfshant)
----------------------------------------------------------------------
Message: 1
Date: Thu, 2 Oct 2014 22:45:29 +0000
From: Theodor Sigurjon Andresson <theodors...@kvenno.is>
To: "centos-docs@centos.org" <centos-docs@centos.org>
Subject: [CentOS-docs] Securing SSH --> Change ports
Message-ID: <9C6DB64A0CF97645A5C90525A4C4C0CC0512C494@CRONUS>
Content-Type: text/plain; charset="us-ascii"
In there you are almost telling people that security through obscurity is a
good way.
That might sometimes be true but in this case it could mean that you would be
handing passwords and other data out.
When you start SSH on port 22 it is done with root privileges because the root user is
the only one that can use ports below 1024. Root is the only user that can listen to that
port or do something with it. If you move the port to 2222 for example you move SSH to a
port that can be used with out a privileged user. This would mean I could write a script
that listens to port 2222 and mimics SSH to capture the passwords. Changing the port of
SSH to 2222 or anything above 1024 makes SSH less secure. Pretty ironic that this is in
the "Securing SSH" chapter. This should never be done.
Location:
http://wiki.centos.org/HowTos/Network/SecuringSSH#head-3579222198adaf43a3ecbdc438ebce74da40d8ec
username: TheodorAndresson
------------------------------
Message: 2
Date: Thu, 02 Oct 2014 15:49:59 -0700
From: Karsten Wade <kw...@redhat.com>
To: centos-docs@centos.org
Subject: Re: [CentOS-docs] Securing SSH --> Change ports
Message-ID: <542dd697.3000...@redhat.com>
Content-Type: text/plain; charset=windows-1252
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On 10/02/2014 03:45 PM, Theodor Sigurjon Andresson wrote:
In there you are almost telling people that security through
obscurity is a good way. That might sometimes be true but in this
case it could mean that you would be handing passwords and other
data out.
When you start SSH on port 22 it is done with root privileges
because the root user is the only one that can use ports below
1024. Root is the only user that can listen to that port or do
something with it. If you move the port to 2222 for example you
move SSH to a port that can be used with out a privileged user.
This would mean I could write a script that listens to port 2222
and mimics SSH to capture the passwords. Changing the port of SSH
to 2222 or anything above 1024 makes SSH less secure. Pretty ironic
that this is in the "Securing SSH" chapter. This should never be
done.
Location:
http://wiki.centos.org/HowTos/Network/SecuringSSH#head-3579222198adaf43a3ecbdc438ebce74da40d8ec
username: TheodorAndresson
_______________________________________________ CentOS-docs mailing
list CentOS-docs@centos.org
http://lists.centos.org/mailman/listinfo/centos-docs
What do you think about using a privileged but unassigned port such as
101?
- - Karsten
- --
Karsten 'quaid' Wade .^\ CentOS Doer of Stuff
http://TheOpenSourceWay.org \ http://community.redhat.com
@quaid (identi.ca/twitter/IRC) \v' gpg: AD0E0C41
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------------------------------
Message: 3
Date: Thu, 2 Oct 2014 23:47:56 +0000
From: Theodor Sigurjon Andresson <theodors...@kvenno.is>
To: Mail list for wiki articles <centos-docs@centos.org>
Subject: Re: [CentOS-docs] Securing SSH --> Change ports
Message-ID: <9C6DB64A0CF97645A5C90525A4C4C0CC0512C4BF@CRONUS>
Content-Type: text/plain; charset="us-ascii"
To change it to unassigned privileged port would be a much better idea if the
user insists on changing it. I personally don't like the idea of security
through obscurity at all.
However if I remember correctly there are some programs that depend on SSH to
be run on port 22. Usually easily changed but sometimes it can't be. I might be
wrong though.
________________________________________
From: centos-docs-boun...@centos.org [centos-docs-boun...@centos.org] on behalf
of Karsten Wade [kw...@redhat.com]
Sent: Thursday, October 02, 2014 22:49
To: centos-docs@centos.org
Subject: Re: [CentOS-docs] Securing SSH --> Change ports
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 10/02/2014 03:45 PM, Theodor Sigurjon Andresson wrote:
In there you are almost telling people that security through
obscurity is a good way. That might sometimes be true but in this
case it could mean that you would be handing passwords and other
data out.
When you start SSH on port 22 it is done with root privileges
because the root user is the only one that can use ports below
1024. Root is the only user that can listen to that port or do
something with it. If you move the port to 2222 for example you
move SSH to a port that can be used with out a privileged user.
This would mean I could write a script that listens to port 2222
and mimics SSH to capture the passwords. Changing the port of SSH
to 2222 or anything above 1024 makes SSH less secure. Pretty ironic
that this is in the "Securing SSH" chapter. This should never be
done.
Location:
http://wiki.centos.org/HowTos/Network/SecuringSSH#head-3579222198adaf43a3ecbdc438ebce74da40d8ec
username: TheodorAndresson
_______________________________________________ CentOS-docs mailing
list CentOS-docs@centos.org
http://lists.centos.org/mailman/listinfo/centos-docs
What do you think about using a privileged but unassigned port such as
101?
- - Karsten
- --
Karsten 'quaid' Wade .^\ CentOS Doer of Stuff
http://TheOpenSourceWay.org \ http://community.redhat.com
@quaid (identi.ca/twitter/IRC) \v' gpg: AD0E0C41
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=y+y6
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------------------------------
Message: 4
Date: Thu, 2 Oct 2014 18:49:37 -0500
From: PJ Welsh <pjwe...@gmail.com>
To: Mail list for wiki articles <centos-docs@centos.org>
Subject: Re: [CentOS-docs] Securing SSH --> Change ports
Message-ID:
<camgrxtebcfrn3siwi29oz_nbh82y_b1_7a_qvpmhyxper68...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
The context for ssh !22 is about what others could/would do to a ssh
daemon. This includes script kiddies or some zero day exploit trolling for
*easy* targets. If you have someone creating a listener on the server, you
have an entirely different issue. How often do you randomly connect to some
system on port 2222 and provide *your* username and password? I am *not*
saying security through obscurity = security, but many IDS/IPS/anti-port
scanners will begin defensive actions when you plow through ports looking
for ssh connection. So instead of being an easier 1 port script kiddie
target you *layer* defenses (including possible STO). Basically anything to
slow down or deter or prevent an attack is good IMHO.
Just my 2cents of course.
pjwelsh
On Thu, Oct 2, 2014 at 5:45 PM, Theodor Sigurjon Andresson <
theodors...@kvenno.is> wrote:
In there you are almost telling people that security through obscurity is
a good way.
That might sometimes be true but in this case it could mean that you would
be handing passwords and other data out.
When you start SSH on port 22 it is done with root privileges because the
root user is the only one that can use ports below 1024. Root is the only
user that can listen to that port or do something with it. If you move the
port to 2222 for example you move SSH to a port that can be used with out a
privileged user. This would mean I could write a script that listens to
port 2222 and mimics SSH to capture the passwords. Changing the port of SSH
to 2222 or anything above 1024 makes SSH less secure. Pretty ironic that
this is in the "Securing SSH" chapter. This should never be done.
Location:
http://wiki.centos.org/HowTos/Network/SecuringSSH#head-3579222198adaf43a3ecbdc438ebce74da40d8ec
username: TheodorAndresson
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Message: 5
Date: Fri, 3 Oct 2014 01:17:09 +0000
From: Theodor Sigurjon Andresson <theodors...@kvenno.is>
To: Mail list for wiki articles <centos-docs@centos.org>
Subject: Re: [CentOS-docs] Securing SSH --> Change ports
Message-ID: <9C6DB64A0CF97645A5C90525A4C4C0CC0512C4DF@CRONUS>
Content-Type: text/plain; charset="us-ascii"
Yes, when securing your services you *layer* defenses that could include using
STO. But when STO is set up in a wrong way it can lead to a security issue. It
isn't good to protect your services to slow down or prevent an attack by
opening up a security risk. As in this case changing the port of SSH to 2222
isn't a good way to include STO. It doesn't matter how big the risk is, you
just don't want this issue to be there. If you want to include STO in your
security measures then you have to do it without opening up a security risk
because you might be opening up a security risk that could be dangerous. In my
opinion that is the case with SSH to port 2222. Changing the port to an
privileged unassigned or unused port is a better way to include STO in your
security measures for SSH. That way you don't have the risk of another user
listening on your SSH.
________________________________________
From: centos-docs-boun...@centos.org [centos-docs-boun...@centos.org] on behalf
of PJ Welsh [pjwe...@gmail.com]
Sent: Thursday, October 02, 2014 23:49
To: Mail list for wiki articles
Subject: Re: [CentOS-docs] Securing SSH --> Change ports
The context for ssh !22 is about what others could/would do to a ssh daemon.
This includes script kiddies or some zero day exploit trolling for *easy*
targets. If you have someone creating a listener on the server, you have an
entirely different issue. How often do you randomly connect to some system on
port 2222 and provide *your* username and password? I am *not* saying security
through obscurity = security, but many IDS/IPS/anti-port scanners will begin
defensive actions when you plow through ports looking for ssh connection. So
instead of being an easier 1 port script kiddie target you *layer* defenses
(including possible STO). Basically anything to slow down or deter or prevent
an attack is good IMHO.
Just my 2cents of course.
pjwelsh
On Thu, Oct 2, 2014 at 5:45 PM, Theodor Sigurjon Andresson
<theodors...@kvenno.is<mailto:theodors...@kvenno.is>> wrote:
In there you are almost telling people that security through obscurity is a
good way.
That might sometimes be true but in this case it could mean that you would be
handing passwords and other data out.
When you start SSH on port 22 it is done with root privileges because the root user is
the only one that can use ports below 1024. Root is the only user that can listen to that
port or do something with it. If you move the port to 2222 for example you move SSH to a
port that can be used with out a privileged user. This would mean I could write a script
that listens to port 2222 and mimics SSH to capture the passwords. Changing the port of
SSH to 2222 or anything above 1024 makes SSH less secure. Pretty ironic that this is in
the "Securing SSH" chapter. This should never be done.
Location:
http://wiki.centos.org/HowTos/Network/SecuringSSH#head-3579222198adaf43a3ecbdc438ebce74da40d8ec
username: TheodorAndresson
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CentOS-docs@centos.org<mailto:CentOS-docs@centos.org>
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------------------------------
Message: 6
Date: Fri, 03 Oct 2014 07:11:15 +0300
From: Manuel Wolfshant <wo...@nobugconsulting.ro>
To: Mail list for wiki articles <centos-docs@centos.org>
Subject: Re: [CentOS-docs] Securing SSH --> Change ports
Message-ID: <542e21e3.1030...@nobugconsulting.ro>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
On 10/03/2014 04:17 AM, Theodor Sigurjon Andresson wrote:
Yes, when securing your services you*layer* defenses that could include using
STO. But when STO is set up in a wrong way it can lead to a security issue. It
isn't good to protect your services to slow down or prevent an attack by
opening up a security risk. As in this case changing the port of SSH to 2222
isn't a good way to include STO. It doesn't matter how big the risk is, you
just don't want this issue to be there. If you want to include STO in your
security measures then you have to do it without opening up a security risk
because you might be opening up a security risk that could be dangerous. In my
opinion that is the case with SSH to port 2222. Changing the port to an
privileged unassigned or unused port is a better way to include STO in your
security measures for SSH. That way you don't have the risk of another user
listening on your SSH.
I agree with you on two things
- changing the default port is not a security measure, it just lowers
the noise in the logs and takes you a bit out of the path of automated
scripts looking for easy targets.
- changing the default port to anything above 1024 creates a greater
risk than using one below 1024
On the other hand, even if it's easier to start a rouge daemon
impersonating sshd to listen on a higher port, if you have a malevolent
user already sniffing on a port - any port - from my point of view you
already have bigger issues than the potential risk you mentioned.
Incidentally I am a fan of using iptables (recent match) to limit the
number of admissible attempts from any given IP to connect to sshd (
yes, I know, it has nothing to do with the initial concern you raised )
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