How To Identify An Ephemeral Port

Hi,

So, I am learning meteor.js and signed up for a (cheap, i.e no support) VPS to host my Meteor app. Everything is running fine but I am trying to understand better how Linux works so here is my question:

I am running CentOS 7 on the VPS but it still uses iptables for its firewall.

I had to enable port 80 to access the web server. However, if I reboot the server, it stops working until I do
Code:

iptables -F

Then everything works. But I am thinking that -F might not be the best thing. I have changed the default SSH port from 22 to something else and that also works but I don't think I ever added it to the iptables rules.

If I do a port scan, the new SSH port is indicated as open as well as port 80 but others are closed as they are supposed to be.

Any idea what is doing on behind the scenes that requires iptables -F for the web access to work properly and if I shouldn't be doing iptables -F (I have it in the rc.local file), what is the right way of doing it?

(BTW, I am computer literate but not that familiar with Linux, which I am trying to learn now.)


Kamal

I just find my server have the below link , it use port 1328 , I checked it called ewall , would advise what is the use of 1328 ewall port in my case ? why it need to use port to access the web , why it can not direct access without the port ? thanks

https://mydomain.com:1328/xxx/xxx/test.html

Hi I'am newbie here,can somebody help me to fix accessing port 22 using ssh anywhere. Please see the sshd_config below:

# Package generated configuration file
# See the sshd(8) manpage for details

# What ports, IPs and protocols we listen for
Port 22
# Use these options to restrict which interfaces/protocols sshd will bind to
#ListenAddress ::
#ListenAddress 0.0.0.0
Protocol 2
# HostKeys for protocol version 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes

# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 768

# Logging
SyslogFacility LOCAL3
LogLevel INFO

# Authentication:
LoginGraceTime 120
PermitRootLogin yes
StrictModes yes
AllowUsers root

RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys

# Don't read the user's ~/.rhosts and ~/.shosts files
IgnoreRhosts yes
# For this to work you will also need host keys in /etc/ssh_known_hosts
RhostsRSAAuthentication no
# similar for protocol version 2
HostbasedAuthentication no
# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
#IgnoreUserKnownHosts yes

# To enable empty passwords, change to yes (NOT RECOMMENDED)
PermitEmptyPasswords no

# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no

# Change to no to disable tunnelled clear text passwords
PasswordAuthentication yes

# Kerberos options
#KerberosAuthentication no
#KerberosGetAFSToken no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
#UseLogin no

#MaxStartups 10:30:60
#Banner /etc/issue.net

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

Subsystem sftp /usr/lib/openssh/sftp-server

UsePAM yes

Hey All,

Is there a way to present a path or other block device to a USB port on a Linux server then have that port connected to a USB port of another device (ie USB to USB) and have it look like a flash disk?

I can plug a USB flash disk to a router just fine. But if I wanted a device to access a path off of another device int he absence of NFS or CIFS capability, that would be handy.

In other words, anyway to assign storage to a USB port in Linux? It would be akin to something like SAN with a target and source just with USB.

Cheers,
DH

Hello,

I have ubuntu server 14.04 running elasticsearch and I'm trying to communicate with elasticsearch from another machine via the browser and http. I believe my problem is that port 9200 is listening for tcp6 not tcp4. Does someone know how to make it listen for ipv4 addresses as well as ipv6?

thanks,
Austin

Hello,
I am using my raspberry pi with Linux 3.18+ installed. I changed the default ssh port from 22 to 16022. This is my sshd_config file:
Code:

# Package generated configuration file
# See the sshd_config(5) manpage for details

# What ports, IPs and protocols we listen for
#Port 22
Port 16022
# Use these options to restrict which interfaces/protocols sshd will bind to
#ListenAddress ::
#ListenAddress 0.0.0.0
Protocol 2

PAM auth is disabled and I only login using password. Now, I checked the authentication log file: /var/log/auth.log. This is a snippet of what it contains:
Quote:
Apr 23 23:44:55 raspberrypi sshd[6473]: Accepted password for pi from 50.252.93.50 port 51978 ssh2
Apr 23 23:52:22 raspberrypi sshd[6477]: Received disconnect from 50.252.93.50: 11: Normal Shutdown
May 5 01:51:02 raspberrypi sshd[4551]: Accepted password for pi from 50.153.109.28 port 30222 ssh
May 5 09:43:47 raspberrypi sshd[6033]: Accepted password for pi from 50.153.110.150 port 21551 ssh2
May 5 09:43:53 raspberrypi sshd[6039]: Received disconnect from 50.153.110.150: 11: Normal Shutdown
May 5 14:09:23 raspberrypi sshd[6783]: Accepted password for pi from 50.153.109.23 port 28684 ssh
May 5 14:32:43 raspberrypi sshd[7008]: Accepted password for pi from 50.153.109.23 port 28689 ssh
May 5 14:37:21 raspberrypi sshd[7014]: Received disconnect from 50.153.109.23: 11: Normal Shutdow
May 8 02:01:41 raspberrypi sshd[24468]: Accepted password for pi from 50.153.110.150 port 30862 ssh2
How is this possible? Why is it showing these random ports for ssh?

This is what 'sudo netstat -nlp' gives:
Code:

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 127.0.0.1:6010          0.0.0.0:*               LISTEN      7923/0
tcp        0      0 0.0.0.0:16022           0.0.0.0:*               LISTEN      2501/sshd
udp        0      0 0.0.0.0:37851           0.0.0.0:*                           2019/dhclient
udp        0      0 0.0.0.0:68              0.0.0.0:*                           2192/dhclient
udp        0      0 0.0.0.0:68              0.0.0.0:*                           2019/dhclient
udp        0      0 192.168.1.82:123        0.0.0.0:*                           2419/ntpd
udp        0      0 192.168.1.78:123        0.0.0.0:*                           2419/ntpd
udp        0      0 127.0.0.1:123           0.0.0.0:*                           2419/ntpd
udp        0      0 0.0.0.0:123             0.0.0.0:*                           2419/ntpd
udp        0      0 0.0.0.0:44953           0.0.0.0:*                           2192/dhclient
Active UNIX domain sockets (only servers)
Proto RefCnt Flags       Type       State         I-Node   PID/Program name    Path
unix  2      [ ACC ]     SEQPACKET  LISTENING     3880     168/udevd           /run/udev/control
unix  2      [ ACC ]     STREAM     LISTENING     8018     2341/dbus-daemon    /var/run/dbus/system_bus_socket

Plus, I am accessing my machine from outside my home network. My router is configured to block all ports, except 16022, whose tcp traffic is forwarded to my raspberry pi. So I don't understand why the log file has these weird ports listed.

SIR

I HAVE RECENTLY INSTALLED CENTOS7 AND CONFIGURED SQUID ON IT . I AM FACING A TYPICAL PROBLEM I AM ABLE TO BROWSE THE NORMAL PAGES BUT WHEN ANY PAGE THAT STARTS WITH HTTPS:\\ IS NOT ALLOWED TO BROWSE.
I HAVE CHECKED MY SQUID.CONF FILE BUT AM UNABLE TO FIND THE PROBLEM.
I HAVE DISABLE SELINEX AND THERE ARE NO RULES IN IPTABLES ALSO.

KINDLY HELP

PASTING MY SQUID.CONF FILE

#
# Recommended minimum configuration:
#

# Example rule allowing access from your local networks.
# Adapt to list your (internal) IP networks from where browsing
# should be allowed
#acl all src all
#acl manager proto cache_object
#acl localhost 127.0.0.1/32
#acl to_localhost dst 127.0.0.0/8 0.0.0.0/32

acl localnet src 191.254.178.0/24 191.254.28.0/24 10.0.43.0/24 10.0.42.0/24
http_access allow localnet
icp_access allow all

acl SSL_ports port 443
acl Safe_ports port 80 # http
acl Safe_ports port 21 # ftp
acl Safe_ports port 443 # https
acl Safe_ports port 70 # gopher
acl Safe_ports port 210 # wais
acl Safe_ports port 1025-65535 # unregistered ports
acl Safe_ports port 280 # http-mgmt
acl Safe_ports port 488 # gss-http
acl Safe_ports port 591 # filemaker
acl Safe_ports port 777 # multiling http
acl CONNECT method CONNECT

#
# Recommended minimum Access Permission configuration:
#
# Deny requests to certain unsafe ports
http_access deny !Safe_ports

# Deny CONNECT to other than secure SSL ports
http_access deny CONNECT !SSL_ports

# Only allow cachemgr access from localhost
#http_access allow localhost manager
http_access allow localnet manager
http_access deny manager

# We strongly recommend the following be uncommented to protect innocent
# web applications running on the proxy server who think the only
# one who can access services on "localhost" is a local user
#http_access deny to_localhost

#
# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
#

# Example rule allowing access from your local networks.
# Adapt localnet in the ACL section to list your (internal) IP networks
# from where browsing should be allowed
#http_access allow localhost

# And finally deny all other access to this proxy
http_access deny all


# Squid normally listens to port 3128
http_port 8899

# Uncomment and adjust the following to add a disk cache directory.
#cache_dir ufs /var/spool/squid 100 16 256

# Leave coredumps in the first cache dir
coredump_dir /var/spool/squid

cache_peer 191.254.178.76 parent 3128 0 no-query no-digest
#icp_access allow all

#
# Add any of your own refresh_pattern entries above these.
#
refresh_pattern ^ftp: 1440 20 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
refresh_pattern . 0 20% 4320

On my firewall I have mapped external port 2022 with internal port 22 for my public ip.
But when i do #ssh <my public ip> 2022
It shows error that verification failed.

Hi

We are going to move some servers from one location to another. How to verify whether the cables are connected to the right interface port?

like one server has eth0 active and eth1 is down. now if the tech guys connect the cable on eth1 port then how to know that

Is it /sys/class/net/eth1 and look for carrier or there is a better way ?

thanks in advance

Hi All,
We have some shell scripts which will send emails about backup, alerts etc using mail command. Example.
Code:

echo "Test Mail" | mail -s "Test" me@mydomain.com

I guess the above command just connect port number 25 of our mail server even if we do not define any port number. Now I would like add smtp port number as 587 in all of the bash scripts. I googled for this but could not get whatever I am expecting. So expecting your kind reply to define smtp port number as 587 in all of the bash scripts.

Thanks in advance.