LinuxQuestions.org

LinuxQuestions.org (/questions/)
-   Linux - Newbie (https://www.linuxquestions.org/questions/linux-newbie-8/)
-   -   Connect to ports Failed ? (https://www.linuxquestions.org/questions/linux-newbie-8/connect-to-ports-failed-4175620714/)

jojolendir 01-02-2018 06:26 AM
Connect to ports Failed ?
 
1 Attachment(s)
Hi

i just installed several application via yum, such as vnc,xrdp
and did opened the certain port needed by the application via iptables


And to be honest im still learning how things working in linux so i don't have any clue why this happen :D,

but basically i cant connect remotely to this port although it stated open and ready to receive connections

here is what netstat print

https://www.linuxquestions.org/quest...1&d=1514895706

Can any some one point me whats wrong?

here is my command during instalation
Code:
[root@server ~]# yum install xrdp tigervnc-server
[root@server ~]# service vncserver start
[root@server ~]# service xrdp start
[root@server ~]# chkconfig xrdp on
[root@server ~]# chkconfig vncserver on
Code:
iptables -I INPUT -p tcp -m state --state NEW -m tcp --dport 3389 -j ACCEPT
service iptables save
service iptables restart

keefaz 01-02-2018 07:12 AM
Why do you open tcp port 3389 while Xvnc is listening on tcp port 5801, 5901 & 6001 (as seen from your netstat output)?

edit
Oh I see, you plan on using xrdp protocol over vnc :study:
Did you check it's a firewall issue with flushing temporarly iptables rules? Maybe you need to start xrdp-sesman as well (not sure)

jojolendir 01-02-2018 08:27 AM
Quote:
Originally Posted by keefaz (Post 5800528)
Why do you open tcp port 3389 while Xvnc is listening on tcp port 5801, 5901 & 6001 (as seen from your netstat output)?

edit
Oh I see, you plan on using xrdp protocol over vnc :study:
Did you check it's a firewall issue with flushing temporarly iptables rules? Maybe you need to start xrdp-sesman as well (not sure)
well its not just remote desktop option ,webmin also not working (port 10000)
and yeah, i did that. also flushing the iptables just like you recommend, starting the service ( xrdp,sessman) but still i cant connect to all this port aside from ssh and apache

like i mention above, im new to linux os so i dont have any clue what causing this but im suspecting its on firewall?

keefaz 01-02-2018 11:25 AM
No, if nothing is filtered, nothing prevents remote hosts to connect to servers at this level

I note from your netstat output that the programs you mention that work listen on IP v4 & v6 traffic while the programs that don't work only listen on IP v4

Do you connect to server using a IP v6 network? If yes, that would explain things. In this case just configure servers so they listen also on IP v6

AwesomeMachine 01-02-2018 05:13 PM
Can you post the output of
Code:
$ iptables -L
. And, rather than taking photos of your monitor, could you please save the output to a file and just post it inside code tags? Are you allowing servers to run on all ports in question in the FW?

You might also want NEW,RELATED,ESTABLISHED in the new rule. And, you might need a rule in the OUTPUT table as well.

I'm not exactly sure how that works with just NEW but nothing else, but I think it might pass on all other traffic on the port, which might eventually be dropped or rejected.

jojolendir 01-06-2018 09:48 AM
Quote:
Originally Posted by AwesomeMachine (Post 5800778)
Can you post the output of
Code:
$ iptables -L
. And, rather than taking photos of your monitor, could you please save the output to a file and just post it inside code tags? Are you allowing servers to run on all ports in question in the FW?

You might also want NEW,RELATED,ESTABLISHED in the new rule. And, you might need a rule in the OUTPUT table as well.

I'm not exactly sure how that works with just NEW but nothing else, but I think it might pass on all other traffic on the port, which might eventually be dropped or rejected.
Hi AM

yes, i believed i can do that..and really sorry for that

Quote:
You have new mail in /var/spool/mail/root
[root@rms ~]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
[root@rms ~]#

keefaz 01-06-2018 01:27 PM
Any error on client side? Network configuration for client is ok?
When you connect via ssh, netstat from server shows client IP as IP v4 or IP v6?

jojolendir 01-06-2018 04:30 PM
Quote:
Originally Posted by keefaz (Post 5803005)
Any error on client side? Network configuration for client is ok?
When you connect via ssh, netstat from server shows client IP as IP v4 or IP v6?

Hi keefaz...


Umm, what is the actual command for this? and sorry for late replying.. to be honest ,you made your point there regarding the ip V6
but i wasn't unsure from the client side, but i think there is no problem i do use ip v4 for my connection (sory cannot use code tags and using screenshot Instead)

it using ipv4 right? and also im using my android Phone(which also failed to connect) , i believe most of Gsm Provider also using only ipv4 right?

And for the active connection on the server ,heres is the result
Code:
[root@rms ~]# netstat -natp
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address              Foreign Address            State      PID/Program name
tcp        0      0 127.0.0.1:199              0.0.0.0:*                  LISTEN      2454/snmpd
tcp        0      0 0.0.0.0:5801                0.0.0.0:*                  LISTEN      2847/Xvnc
tcp        0      0 0.0.0.0:3306                0.0.0.0:*                  LISTEN      2641/mysqld
tcp        0      0 0.0.0.0:5901                0.0.0.0:*                  LISTEN      2847/Xvnc
tcp        0      0 0.0.0.0:111                0.0.0.0:*                  LISTEN      2136/portmap
tcp        0      0 0.0.0.0:10000              0.0.0.0:*                  LISTEN      3020/perl
tcp        0      0 0.0.0.0:6001                0.0.0.0:*                  LISTEN      2847/Xvnc
tcp        0      0 127.0.0.1:3350              0.0.0.0:*                  LISTEN      2696/xrdp-sesman
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                  LISTEN      2484/sshd
tcp        0      0 127.0.0.1:631              0.0.0.0:*                  LISTEN      2497/cupsd
tcp        0      0 127.0.0.1:25                0.0.0.0:*                  LISTEN      2718/sendmail
tcp        0      0 0.0.0.0:665                0.0.0.0:*                  LISTEN      2179/rpc.statd
tcp        0      0 0.0.0.0:3389                0.0.0.0:*                  LISTEN      2692/xrdp
tcp        0  2040 172.16.2.195:22            my ip address:50764      ESTABLISHED 8000/sshd
tcp        0      0 :::80                      :::*                        LISTEN      2755/httpd
tcp        0      0 :::6001                    :::*                        LISTEN      2847/Xvnc
tcp        0      0 :::22                      :::*                        LISTEN      2484/sshd
tcp        0      0 :::443                      :::*                        LISTEN      2755/httpd
tcp        0      0 ::ffff:127.0.0.1:35383      ::ffff:127.0.0.1:25        TIME_WAIT  -
tcp        0      0 ::ffff:127.0.0.1:35384      ::ffff:127.0.0.1:25        TIME_WAIT  -
[root@rms ~]#

keefaz 01-06-2018 04:40 PM
You have multiple local networks? (172.16.2 and 192.168.100)

jojolendir 01-06-2018 05:10 PM
For the technical detail i haven't ask the server admin, but its possible

do you think that's the problem?

keefaz 01-06-2018 05:18 PM
Your posted image shows client configuration to connect on a network with address 192.168.100 while the server seems to be on network with address 172.16.2...

edit
But I see DHCP enabled, so maybe these client addresses are just Windows default addresses
(I don't know well Windows, sorry)

Do you have telnet in Windows? If yes try open a dos terminal and:
Code:
telnet 172.16.2.195 3389
See if it shows any output

jojolendir 01-07-2018 05:14 AM
Quote:
Originally Posted by keefaz (Post 5803077)
Your posted image shows client configuration to connect on a network with address 192.168.100 while the server seems to be on network with address 172.16.2...

edit
But I see DHCP enabled, so maybe these client addresses are just Windows default addresses
(I don't know well Windows, sorry)

Do you have telnet in Windows? If yes try open a dos terminal and:
Code:
telnet 172.16.2.195 3389
See if it shows any output
But keefaz my home connection or Net connection from GSM Provider isn't part of my server network ,i mean isn't 172.16.xxx or 192.168.xxx is an internal private ip address? as for 192.168 (my ip) ,it assigned by my router and on the netstat output. it wasn't 192.168.xxx but my real public ip

sorry if i make confusion

Code:
[root@rms ~]# netstat -natp
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address              Foreign Address            State      PID/Program name
tcp        0      0 127.0.0.1:199              0.0.0.0:*                  LISTEN      2454/snmpd
tcp        0      0 0.0.0.0:5801                0.0.0.0:*                  LISTEN      2847/Xvnc
tcp        0      0 0.0.0.0:3306                0.0.0.0:*                  LISTEN      2641/mysqld
tcp        0      0 0.0.0.0:5901                0.0.0.0:*                  LISTEN      2847/Xvnc
tcp        0      0 0.0.0.0:111                0.0.0.0:*                  LISTEN      2136/portmap
tcp        0      0 0.0.0.0:10000              0.0.0.0:*                  LISTEN      3020/perl
tcp        0      0 0.0.0.0:6001                0.0.0.0:*                  LISTEN      2847/Xvnc
tcp        0      0 127.0.0.1:3350              0.0.0.0:*                  LISTEN      2696/xrdp-sesman
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                  LISTEN      2484/sshd
tcp        0      0 127.0.0.1:631              0.0.0.0:*                  LISTEN      2497/cupsd
tcp        0      0 127.0.0.1:25                0.0.0.0:*                  LISTEN      2718/sendmail
tcp        0      0 0.0.0.0:665                0.0.0.0:*                  LISTEN      2179/rpc.statd
tcp        0      0 0.0.0.0:3389                0.0.0.0:*                  LISTEN      2692/xrdp
tcp        0  2040 172.16.2.195:22            202.167.44x.xxx:50764       ESTABLISHED 8000/sshd
tcp        0      0 :::80                      :::*                        LISTEN      2755/httpd
tcp        0      0 :::6001                    :::*                        LISTEN      2847/Xvnc
tcp        0      0 :::22                      :::*                        LISTEN      2484/sshd
tcp        0      0 :::443                      :::*                        LISTEN      2755/httpd
tcp        0      0 ::ffff:127.0.0.1:35383      ::ffff:127.0.0.1:25        TIME_WAIT  -
tcp        0      0 ::ffff:127.0.0.1:35384      ::ffff:127.0.0.1:25        TIME_WAIT  -
[root@rms ~]#
but anyway Here the output telnet from my Home Desktop
Code:
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Users\George B>telnet 172.16.2.195 3389
Connecting To 172.16.2.195...Could not open connection to the host, on port 3389
: Connect failed

C:\Users\George B>
But From server side maybe make sense if the telnet executed from my server ? and here's the out put

Code:
[root@rms ~]# telnet 172.16.2.195 3389
Trying 172.16.2.195...
Connected to 172.16.2.195 (172.16.2.195).
Escape character is '^]'.
it does connected to the specific port

keefaz 01-07-2018 05:23 AM
Ah I didn't realize you want to connect from outside the local network...

How the external connections are routed to the server? With a router?
If yes, is tcp port 3389 forwarded to the server in the router?

jojolendir 01-07-2018 06:11 AM
Regarding Forwarded port, to be honest i have no idea :D

(from my isp line >> OpenWrt Luci default configuration >> Desktop or any device ).

i just know it work i mean, it didn't have any problem connecting to other server aside this one

This is really make me curious to find out whats is the culprit especially when you mention about 172.16

Code:
tcp        0  2040 172.16.2.195:22            202.167.44x.xxx:50764      ESTABLISHED 8000/sshd
isnt 172.16.2.195:22 one should also my real public server ip address?

keefaz 01-07-2018 10:53 AM
No,172.16.2.xxx is ip range reserved for local network
https://en.wikipedia.org/wiki/Private_network

I think it could be a routing issue here (tcp port 3389 not routed to local server)


All times are GMT -5. The time now is 04:24 PM.