[Nut-upsuser] NUT Client Not Working, Server OK
wolfy at nobugconsulting.ro
Wed Feb 16 23:29:08 GMT 2022
On 2/16/22 17:06, William Cole via Nut-upsuser wrote:
> Hello All,
> I ran telnet on both machines:
> First from the server  to the client 
> Then from the client  to the server 
> The result in both cases:
> Trying 192.168.1.xxx
> telnet: Unable to connect to remote host: Connection refused.
I am 90% sure that you have a firewall that blocks TCP connections. Many
modern linux distros come with a default firewall which blocks all
incoming connections or allow a very limited subset of ports, like ssh
( port 22 ) and web ( port 80 and/or 443 ).
You can do a quick test by running as root ( or via sudo if needed ) one
of the following two commands on the server machine:
iptables -I INPUT -p tcp --dport 3493 -j ACCEPT <== this will
enable access to port TCP/3493
iptables -F <=== this should disable the firewall completely. Note
that depending on the distribution that you use, a more civilized way to
( temporary ) disable the firewall exists, for instance in recent
Debian/Ubuntu you'd run /ufw disable/ while on CentOS/RHEL you'd use
/systemctl stop firewalld ( /with the obvious /ufw enable/ resp
/systemctl start firewalld/ to enable the firewall back )
If I am right, once you've allowed the incoming connection, repeating
the telnet command should succeed. In this case you must modify the
firewall and add a permanent rule to allow the connection.
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