Making A Port Listen For Ipv4

Hello,

I try to use a ftp daemon and a Telnet daemon with inetd and the BusyBox v1.19.0 on a linux 2.6.24.

When running inetd and then checking what is listening with "netstat -an |grep LISTEN" i have :
Code:

netstat: /proc/net/tcp6: No such file or directory
netstat: /proc/net/udp6: No such file or directory
netstat: /proc/net/raw6: No such file or directory
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN

tcp        0      0 0.0.0.0:21              0.0.0.0:*               LISTEN

tcp        0      0 0.0.0.0:23              0.0.0.0:*               LISTEN

ftp port 21 and Telnet port 23 seems to be listening.

My inetd.conf file is :

Code:

#<service_name>    <sock_type>    <proto>    <flags> <user>     <server_path>     <args> 

21 stream tcp nowait root ftpd ftpd /etc
telnet            stream        tcp        nowait    root    /usr/sbin/telnetd

I have no rule in my hosts.deny so nothing should be stopped and i have no iptables firewall in place too.

When typing "ftp://ipofthetarget" in a web browser i have a error :

Code:

504 Gateway Timeout
Gateway timeout expired while waiting for server response.

And when trying to Telnet from another computer or "Telnet localhost" from the board i have :
Code:

# telnet 10.2.29.201
Trying 10.2.29.201...
connected to 10.2.29.201.
Escape character is '^]'

Connection closed by foreign host.

This would mean that the connection for Telnet exist but why is it closing ?

Thank you for your future answers !

UPDATE 1 :
If i try to run telnetd like this :
/usb/sbin/telnet -l /bin/sh
i can connect anonymously from another computer, not perfect because i would like a user/password but still of use.
The problem with the ftp daemon still exist.

UPDATE 2 :
Trying from Windows cmd or linux terminal : ftp ipofthetarget seems to work
Not perfect because i would like a user/password too but still of use.

I am still open for suggestion for the user/password thing. I am not deleting the thread in case someone interested about this exist.

Hi all,

I understand that Linux by default will limit its Ephemeral port allocation between 32768 to 61000.

I need to identify the applications running on my box (around 500 of them) which are intentionally using a port which happens to be in Ephemeral port range. Objective is to get a list of those apps and flag it so that the developers get to know of it and change their application port.

When I run netstat -nap to get a list of listen ports, I am unable to figure out if the port in Ephemeral range is actually allocated by OS or one of my apps has done it.


Thanks,
linux_it_is

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.

I am trying to allow local users to us the ftp for my site (really, any user would work, I just thought this would be easiest). I am trying to make it so that I can upload themes, install plugins, etc on a WordPress site hosted on my Ubuntu 14.04 machine. Here is the contents of my vsftpd.conf file from /etc/

# Example config file /etc/vsftpd.conf
#
# The default compiled in settings are fairly paranoid. This sample file
# loosens things up a bit, to make the ftp daemon more usable.
# Please see vsftpd.conf.5 for all compiled in defaults.
#
# READ THIS: This example file is NOT an exhaustive list of vsftpd options.
# Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's
# capabilities.
#
#
# Run standalone? vsftpd can run either from an inetd or as a standalone
# daemon started from an initscript.
listen=YES
#
# Run standalone with IPv6?
# Like the listen parameter, except vsftpd will listen on an IPv6 socket
# instead of an IPv4 one. This parameter and the listen parameter are mutually
# exclusive.
#listen_ipv6=YES
#
# Allow anonymous FTP? (Disabled by default)
anonymous_enable=NO
#
# Uncomment this to allow local users to log in.
local_enable=YES
#
# Uncomment this to enable any form of FTP write command.
write_enable=YES
#
# Default umask for local users is 077. You may wish to change this to 022,
# if your users expect that (022 is used by most other ftpd's)
local_umask=022
#
# Uncomment this to allow the anonymous FTP user to upload files. This only
# has an effect if the above global write enable is activated. Also, you will
# obviously need to create a directory writable by the FTP user.
#anon_upload_enable=YES
#
# Uncomment this if you want the anonymous FTP user to be able to create
# new directories.
#anon_mkdir_write_enable=YES
#
# Activate directory messages - messages given to remote users when they
# go into a certain directory.
dirmessage_enable=YES
#
# If enabled, vsftpd will display directory listings with the time
# in your local time zone. The default is to display GMT. The
# times returned by the MDTM FTP command are also affected by this
# option.
use_localtime=YES
#
# Activate logging of uploads/downloads.
xferlog_enable=YES
#
# Make sure PORT transfer connections originate from port 20 (ftp-data).
connect_from_port_20=YES
#
# If you want, you can arrange for uploaded anonymous files to be owned by
# a different user. Note! Using "root" for uploaded files is not
# recommended!
#chown_uploads=YES
#chown_username=whoever
#
# You may override where the log file goes if you like. The default is shown
# below.
#xferlog_file=/var/log/vsftpd.log
#
# If you want, you can have your log file in standard ftpd xferlog format.
# Note that the default log file location is /var/log/xferlog in this case.
#xferlog_std_format=YES
#
# You may change the default value for timing out an idle session.
#idle_session_timeout=600
#
# You may change the default value for timing out a data connection.
#data_connection_timeout=120
#
# It is recommended that you define on your system a unique user which the
# ftp server can use as a totally isolated and unprivileged user.
#nopriv_user=ftpsecure
#
# Enable this and the server will recognise asynchronous ABOR requests. Not
# recommended for security (the code is non-trivial). Not enabling it,
# however, may confuse older FTP clients.
#async_abor_enable=YES
#
# By default the server will pretend to allow ASCII mode but in fact ignore
# the request. Turn on the below options to have the server actually do ASCII
# mangling on files when in ASCII mode.
# Beware that on some FTP servers, ASCII support allows a denial of service
# attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd
# predicted this attack and has always been safe, reporting the size of the
# raw file.
# ASCII mangling is a horrible feature of the protocol.
#ascii_upload_enable=YES
#ascii_download_enable=YES
#
# You may fully customise the login banner string:
#ftpd_banner=Welcome to blah FTP service.
#
# You may specify a file of disallowed anonymous e-mail addresses. Apparently
# useful for combatting certain DoS attacks.
#deny_email_enable=YES
# (default follows)
#banned_email_file=/etc/vsftpd.banned_emails
#
# You may restrict local users to their home directories. See the FAQ for
# the possible risks in this before using chroot_local_user or
# chroot_list_enable below.
#chroot_local_user=YES
#
# You may specify an explicit list of local users to chroot() to their home
# directory. If chroot_local_user is YES, then this list becomes a list of
# users to NOT chroot().
# (Warning! chroot'ing can be very dangerous. If using chroot, make sure that
# the user does not have write access to the top level directory within the
# chroot)
#chroot_local_user=YES
#chroot_list_enable=YES
# (default follows)
#chroot_list_file=/etc/vsftpd.chroot_list
#
# You may activate the "-R" option to the builtin ls. This is disabled by
# default to avoid remote users being able to cause excessive I/O on large
# sites. However, some broken FTP clients such as "ncftp" and "mirror" assume
# the presence of the "-R" option, so there is a strong case for enabling it.
#ls_recurse_enable=YES
#
# Customization
#
# Some of vsftpd's settings don't fit the filesystem layout by
# default.
#
# This option should be the name of a directory which is empty. Also, the
# directory should not be writable by the ftp user. This directory is used
# as a secure chroot() jail at times vsftpd does not require filesystem
# access.
secure_chroot_dir=/var/run/vsftpd/empty
#
# This string is the name of the PAM service vsftpd will use.
pam_service_name=vsftpd
#
# This option specifies the location of the RSA certificate to use for SSL
# encrypted connections.
rsa_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
# This option specifies the location of the RSA key to use for SSL
# encrypted connections.
rsa_private_key_file=/etc/ssl/private/ssl-cert-snakeoil.key

I am facing problem in enabling the DNS Log making in named.conf file.
My /etc/named.conf file structure is as follows:
-------------------------------------------------------------
//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//

options {
listen-on port 53 { 127.0.0.1; 10.40.124.2; };
listen-on-v6 port 53 { ::1; };
directory "/var/named";
dump-file "/var/named/data/cache_dump.db";
statistics-file "/var/named/data/named_stats.txt";
memstatistics-file "/var/named/data/named_mem_stats.txt";
allow-query { localhost; 10.40.124.2; };
recursion yes;

dnssec-enable yes;
dnssec-validation yes;
dnssec-lookaside auto;

/* Path to ISC DLV key */
bindkeys-file "/etc/named.iscdlv.key";

managed-keys-directory "/var/named/dynamic";
};

logging {
channel default_debug {
file "/var/log/named.run";
severity dynamic;
print-time yes;
};

channel queries_channel {
file "/var/log/queries.log";
severity dynamic;
print-time yes;
print-severity yes;
};
channel security_channel {
file "/var/log/security.log" versions 3 size 5m;
severity debug 3;
print-category yes;
print-severity yes;
print-time yes;
};

channel update_security_channel {
file "/var/log/updates.log" versions 3 size 5m;
severity debug 3;
print-category yes;
print-severity yes;
print-time yes;
};

channel dnssec_channel {
file "/var/log/dnssec.log" versions 3 size 5m;
severity debug 3;
print-category yes;
print-severity yes;
print-time yes;
};

channel xfers_channel {
file "/var/log/zone_transfers.log" versions 3 size 5m;
severity debug 3;
print-category yes;
print-severity yes;
print-time yes;
};

category queries { queries_channel; };
category security { security_channel; };
category update-security { update_security_channel; };
category dnssec { dnssec_channel; };
category xfer-out { xfers_channel; };
};
zone "." IN {
type hint;
file "named.ca";
};

include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";
----------------------------------------------------------------
My DNS Server works fine. Only it cannot make the log.
when I will run this command:
#dig -x 10.40.124.2
the result comes fine but the log is not make in /var/log/queries.log file.
The named is running without chroot enviroment.
Please help me in solving this.

Ok I'm really new at this . Not the old DOS I'm used to. I'm trying to setup my home server using Ubuntu 12.0.4, I've had no success. I have an actual raid sever I'm using. Loaded first HD with Ubuntu 12.0.4, now trying to setup so I can access from anywhere. Remember I'm a newbie so try and keep it simple until I learn Linux. I have my router setup for port forward using 192.168.100 port 21. everything I looked at so far is pretty complicated for a new user. Any help would be great.

I suspect this is not possible but I'll ask.

For machine where SSHd is listening on multiple IP addresses, is it possible to block certain users logging in based on the IP address they are connecting to?

Example:
Listening on 1.2.3.4 and 5.6.7.8
User amir should be allowed to log in on 1.2.3.4 but NOT 5.6.7.8
User mary is allowed on 5.6.7.8 but not on 1.2.3.4

Again, these are the IP addresses the user is connecting TO not FROM.

I think I could do this by running multiple sshd instances but can I do it with a single one?

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

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