On Monday 23 March 2009 16:57:45 JohnS wrote: > On Mon, 2009-03-23 at 16:26 +0000, Anne Wilson wrote: > > On Monday 23 March 2009 15:29:53 JohnS wrote: > > > On Mon, 2009-03-23 at 14:31 +0000, Anne Wilson wrote: > > > > On Tuesday 23 December 2008 15:38:17 Warren Young wrote: > > > > > Michael Simpson wrote: > > > > > >> GRC reports that ports are stealthed > > > > > > > > > > > > Try www.auditmypc.com or nmap-online.com rather than grc to look > > > > > > for open ports > > > > > > > > > > What advantages do they have, in your opinion? > > > > > > > > > > >> there a better way than opening port 143? > > > > > > > > > > > > ssh tunnelling? > > > > > > > > > > I agree, though the default CentOS sshd configuration requires some > > > > > tightening down to trust it on Internet-facing servers, IMHO: > > > > > > > > > > 1. In /etc/ssh/sshd_config, set "PasswordAuthentication no". No > > > > > matter how good your password, it isn't as good as using keys. > > > > > Remember, forwarding ssh opens it to pounding 24x7 from any of the > > > > > millions on zombie boxes on the Internet. > > > > > > > > > > 2. On the machine(s) that you want to allow logins from, run > > > > > "ssh-keygen -t rsa" to generate a key pair, if you haven't already. > > > > > Then copy the contents of ~/.ssh/id-rsa.pub into > > > > > ~/.ssh/authorized_keys on your home server. These keys are used to > > > > > authenticate the remote system, in lieu of a password or physical > > > > > token. You could put these keys on a USB stick instead, if you > > > > > didn't want to keep them permanently on the remote hosts. > > > > > > > > > > 3. Disable SSHv1 protocol support in /etc/ssh/sshd_config: > > > > > "Protocol 2", not "Protocol 2,1". SSHv1 has known weaknesses. > > > > > Boggles my mind that it's still enabled by default.... > > > > > > > > > > 4. Same file, set "PermitRootLogin no" if it isn't already. > > > > > > > > > > (Aside: I also like to set up sudo with one account allowed to do > > > > > anything, then lock the root account, so the only way to get root > > > > > access is to log in as a regular user then sudo up, reducing the > > > > > risk of passwordless keys.) > > > > > > > > > > Having done all this, you're ready to allow remote access: > > > > > > > > > > 5. In your router, forward a high-numbered port to 22 on the > > > > > server. If it's not smart enough to use different port numbers on > > > > > either side, you can change the sshd configuration so it listens on > > > > > a different port instead. I like to use 22022 for this. > > > > > > > > > > This is *not* security through obscurity. It's simply a way to > > > > > reduce the amount of log spam you have to dig through when > > > > > monitoring your system's behavior. Everything that appears in your > > > > > logs should be *interesting*. Constant port knocking from worms > > > > > and script kiddies is not interesting. > > > > > > > > > > In case you've not done ssh tunelling, Anne, the command that does > > > > > what you want, having done all the above is: > > > > > > > > > > $ ssh -p22022 -L10143:my.server.com:143 anne@xxxxxxxxxxxxx > > > > > > > > > > This sets up port 10143 on the local system to be redirected > > > > > through the ssh session to the IMAP port on your home server. You > > > > > don't want to redirect 143 to 143 because that would require you to > > > > > run ssh as root. It also prevents you from using this on a system > > > > > that itself has an IMAP server. > > > > > > > > > > With the tunnel up, you can set up your mail client to connect to > > > > > port 10143 on localhost, and you'll be looking at your remote mail > > > > > server. > > > > > > > > Hello again. You were kind enough to give me this advice last > > > > December. I've another holiday approaching and thought it was time > > > > that I got this sorted. Unfortunately, I'm not sure that I can do > > > > this, so I'm asking your opinion. > > > > > > > > My router is a Netgear DG834G. I can create a service, tell it which > > > > ports to open, and say which local IP I want it sent to. However, I > > > > can't see any way to set the port to which it should be forwarded as > > > > anything other than the incoming port. IOW, I can enable the new > > > > service Ext-ssh, which accepts incoming traffic on port 22022, and > > > > direct it to my server on 192.168.0.40, but I can't see how to make > > > > it send that traffic to port 22 on the server. > > > > > > > > Am I totally misunderstanding this? Really all I want is to be able > > > > to log in to the server if I get an email alert that there is a > > > > problem or security updates pending. If I can get this sorted, I'll > > > > look again at how to route the IMAP mail through the tunnel too. > > > > > > --- > > > http://kbserver.netgear.com/kb_web_files/n101145.asp > > > http://kbserver.netgear.com/kb_web_files/n101145.asp#FR114PAnchor > > > > Sure, but those pages are very much like the router's doc pages. I don't > > see any info about forwarding to ports different from the incoming one. > > --- > Her's another example it will do what you want, your just > misunderstanding it. I have 2 customers that use Netgear routers. I > think your not setting up the Nat - Add Page. > http://portforward.com/english/routers/port_forwarding/Netgear/DG834G/eMule >.htm One thing are you using it for the DSL or another modem/router for dsl? > If your using two only one can be Natted and the other Main router in > Bridged Mode. The router is also the DSL modem. OK - I'm thick. I've looked at that page and seen only what I'm already familiar with. Please, in plain English, how do I set ssh to come in on port 22022 (service called ext-ssh already set up for that) to be forwarded to 192.168.0.xx port 22? Anne -- New to KDE4? - get help from http://userbase.kde.org Just found a cool new feature? Add it to UserBase
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