change ssh port

sandeepthug · 03-10-2010, 10:55 PM

Hi i need to change ssh port on the servers including centos and ubuntu

when i make changes to /etc/ssh/sshd.config and change the port to something else

restart sshd

then i can determine that port 22 is not working
but ssh does not connect to new port
it says "no route to the host"
Please help

sandeep

blacky_5251 · 03-10-2010, 11:06 PM

Your firewall on the server is probably blocking the new port. You need to modify your firewall to allow access to the new port, and close access to port 22.

sandeepthug · 03-11-2010, 12:02 AM

how do i modify the server firewall
i don't know iptables

thanks
sandeep

mario.almeida · 03-11-2010, 12:33 AM

Hi,

1) Is the server and the PC you want to connect are in the same network?
2) What is the OS on the server?

sandeepthug · 03-11-2010, 12:40 AM

yes they are on the same network

i am using ubuntu 9.10 and centos 5.3

blacky_5251 · 03-11-2010, 12:53 AM

Are you able to disable the firewall to confirm it is causing the problem? Obviously if this machine is facing the internet then this isn't a great idea.

I don't know Ubuntu, but you can control the CentOS firewall using the GUI without having to know iptables. Go to System, then Administration and you should find "Security Level and Firewall". If you don't have access to the GUI, then run system-config-security-level-tui from the command prompt.

mario.almeida · 03-11-2010, 02:07 AM

Hi,

On the server do the following

Post the output of

Quote:

cat /etc/sysconfig/network-scripts/ifcfg-<iface>

replace <iface> with the actual interface i.e eth0 or eth1 etc..

Verify if sshd is started with the new port

Quote:

netstat -pant | grep ":<new ssh-port>" | grep LISTEN

Stop iptables on the server

Quote:

/etc/init.d/iptables stop

On the Desktop
How have you configured your network settings command line or GUI

Verify your network settings with the below command

Quote:

ifconfig

I hope you are trying to connect to the server by mentioning the new port as below

Quote:

ssh -p <new ssh-port> <server-ip>

sandeepthug · 03-11-2010, 03:43 AM

Hi All
i tried to change the port once again from /etc/ssh/sshd-config
changed it and
restarted sshd
everything works like charm

i don't know what was happening yesterday

thanks all

nowonmai · 03-11-2010, 06:35 AM

Just FYI - 'no route to host' is a networking problem... most likely that the IP specified is not on the same subnet. If the problem was a port or firewall issue, the message would have been 'connection refused'.

blacky_5251 · 03-11-2010, 04:04 PM

Of course it is. I should read the OP more carefully