Can't SSH from outside

Article Details
URL: http://support.rhinoequipment.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=94
Article ID: 94
Created On: 24 Jun 2009 04:23 PM

Answer

TroubleShooting SSH

 Often for troubleshooting we will require an SSH connection. In some cases we will be unable to establish a connection due to some configuration issue. This article hopes to provide some troubleshooting direction. Please note this article is for informational purposes only and contains things not supported by Rhino


To establish an SSH connection the unit needs to either be directly on a public ip or have port 22 routed through NAT to the unit. Most routers have some form of a port forwarding option. You should check your operating manual on how to foreword ports. Information on forwarding for most consumer routers can be found at http://portforward.com/ .

If you are able to access SSH locally but not remotely it is usually for 1 of 3 reasons.

 1. The ports are not forwarded correctly or the firewall is not honoring the forward try restarting the firewall.
 2. Your system has no default gateway set.
       -- See http://www.cyberciti.biz/faq/linux-setup-default-gateway-with-route-command/ for information.
 3. Your box may have an IPTables rule set to deny people outside your subnet
      --you can try:
             iptables -A INPUT -p tcp --dport 22 -j ACCEPT
         iptables -A OUTPUT -p tcp --sport 22 -j ACCEPT
         ==OR==
         /etc/init.d/iptables stop

 4. SSH may be blocked by certain ISP's

If you can not SSH in locally it is possible your configurations are wrong.

1.  Try to ping the Internet from a local terminal.
      -- ping -c 3 google.com
      If you can't ping out check your physical connections and the items mentioned above.
2. Make sure your IP settings are all correct. If you are set to  static IP try switching to DHCP.

3. Check to make sure the system is configured for port 22.
     -- netstat -atnp | grep sshd

With any luck the above information should be enough to find your issue and/or resolve it.