Security Basics mailing list archives
RE: SSH connection attempts in logs.
From: "Nick Vaernhoej" <nick.vaernhoej () capitalcardservices com>
Date: Tue, 2 Oct 2007 08:38:11 -0500
Good morning, Thank you everyone. I am realizing that I didn't ask the right question. I am not concerned about the connection. The log entry is from the firewall where this isn't an allowed connection. We do not have any ssh servers accessible from the outside. I am curious about the connection closing on tcp/0 and I failed to say that initiating the connection on tcp/22 was one of a number I could have chosen. There are a lot of different port numbers being hit where they close on tcp/0 Thanks Nick Vaernhoej "Quidquid latine dictum sit, altum sonatur." -----Original Message----- From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of jason Sent: Sunday, September 30, 2007 8:02 PM To: security-basics () securityfocus com Subject: Re: SSH connection attempts in logs. I have encountered similar issues and chances are, if you do not know who is trying to connect to you, safer to block first and respond later. If a an 'admin' or a 'staff' member is idiotic enough to screw it up more then 3 times, they need a lesson in security and whatnot. after a good row, I sincerely doubt they will login erroneously too often. At that point, no harm no foul. Honestly. As an administrator of an SSH running machine, if you don't recognize an IP or even the range that it's coming from, what choice do you have but to block it? Even if you do recognize the range and there are multiple failures? See previous response. Why would you need a secure shell if you didn't care who was connecting to your boxen? What I typically do to circumvent the default for scanners and similar ilk is to just change the port that ssh is on or to forward from the firewall a specific port. I have also seen mention of 'knock' style programs but have not had the spare time to implement a working 'knock' setup. At that point what do you care (for the most part) is hitting port 22? This just falls under basic security steps though and I am guessing is far from new information. Jason Tarbet Computer Nerd Bangor Humane Society ChromeSilver wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Dan Denton schrieb:Well, I wouldn't lean toward anything that tries to connect on port
22 as
noise. I would verify that the src IP address isn't some legitimate
attempt
to connect by an application that is simply misconfigured. If it's
not
legit, block it. In that case it's most likely an attack, or it could
be a
port scanner. Just my two cents.xxx.xxx.xxx.xxx = them yyy.yyy.yyy.yyy = me c=262144 m=98 msg="Connection Opened" n=187596 src=xxx.xxx.xxx.xxx:32881:X1 dst=yyy.yyy.yyy.yyy:22:X1 proto=tcp/22 c=1024 m=537 msg="Connection Closed" n=139129 src=xxx.xxx.xxx.xxx:32881:X1 dst=yyy.yyy.yyy.yyy:0:X1 proto=tcp/0Yep, that's my guess too. It's some kind of port scanner very likely. Since it isn't probing weak accounts (like root /w empty pw), so it cant be
a
vuln scanner. But I wouldn't suggest blocking that IP, it could be a dial-up conn. Better do a whois on that IP and then tell the ISP that you're most likely being scanned from it. Then you could, eg. contact that person via snailmail and let it know that there's an aware admin online... Grz, ChromeSilver - -- "If light be the brightest light... Wherfore then doth it shadows cast?" - -R.Rohonyi -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (MingW32) iD8DBQFG+0FCDZBprASGxfQRAmZ5AKCUOfJqIrxhlAUkrpfrMdNOHe0X+wCeL8oE +NQu5JZ+eKqnQMlw8ZkPHvE= =46vA -----END PGP SIGNATURE-----
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Current thread:
- Re: SSH connection attempts in logs. jason (Oct 01)
- RE: SSH connection attempts in logs. Dan Denton (Oct 01)
- Message not available
- RE: SSH connection attempts in logs. Nick Vaernhoej (Oct 02)