Security Basics mailing list archives
RE: Is this normal?
From: "Shawn Jackson" <sjackson () horizonusa com>
Date: Fri, 22 Oct 2004 08:26:39 -0700
I'm not very experienced with this sort of thing so please bear with me.
Seaming I don't know jack, please bear with me.
Checking my logs today I was a bit surprised to find about 80 refused connection attempts to my sshd during the last month like: Oct 7 21:22:27 firewall sshd[9710]: refused connect from xxx.xxx.xxx.xxx
It's common. They are, most likely, automated scans trying to find vulnerable OpenSSH systems. Remember to always keep it patched. Also I recommend that if you know where you would be logging in from, i.e. from work, etc, to explicitly deny everything and allow access to your known login points.
I did reverse lookups on the IP's with dig and found that the attemts originated from a variety of hosts from Italy, Polen, Russia, Sweden and Pakistan to name but a few.
Yep, it's time to kick them all off the Internet.
One particular host had tried connecting 19 times with just a few seconds between tries (is he/she just trying different commonly used passwords?)
Automated system, yes, common passwords. Like guest, root with blank pass, root with root, etc, etc.
Is this Normal?
Yes.
Should I be concerned?
Always.
Any security tips, suggestions, thoughts? (I update regularly with swaret (SlackwareTool), use strong random passwords, tcp wrappers) Anyone know a good guide to hardening Slackware? Anything else you'd like to mention?
First, use only Version 2 of SSH. Second firewall (Netfilter or hardware) access to SSH, allow only the host/systems you know that you will use to gain access to SSH. Third, deny root login from SSH, remember to only use SU or limited sudo. Shawn Jackson Systems Administrator Horizon USA 1190 Trademark Dr #107 Reno NV 89521 www.horizonusa.com Email: sjackson () horizonusa com Phone: (775) 858-2338 (800) 325-1199 x338 Fax: (775) 858-2330
Current thread:
- Is this normal? Erlend Lorentzen (Oct 21)
- Re: Is this normal? Joe Polk (Oct 22)
- Re: Is this normal? Barrie Dempster (Oct 27)
- Re: Is this normal? Kluge (Oct 27)
- Re: Is this normal? Kenneth R Swain II (Oct 27)
- Re: Is this normal? Barrie Dempster (Oct 27)
- Re: Is this normal? Adam Jones (Oct 22)
- Re: Is this normal? Callan K L Tham (Oct 25)
- Re: Is this normal? xyberpix (Oct 25)
- <Possible follow-ups>
- RE: Is this normal? Shawn Jackson (Oct 22)
- RE: Is this normal? Andrew Shore (Oct 22)
- Re: Is this normal? bp1974 (Oct 22)
- Re: Is this normal? Jonathan Loh (Oct 25)
- Re: Is this normal? xyberpix (Oct 26)
- Re: Is this normal? Jonathan Loh (Oct 26)
- Re: Is this normal? Jonathan Loh (Oct 25)
- Re: Is this normal? Joe Polk (Oct 22)
- Re: Is this normal? H Carvey (Oct 26)