Block direct SSH to root, but not to root equivalent

The PermitRootLogin no option of /etc/ssh/sshd_config will block all the users with UID 0. Below is an option to overcome this.

# vi /etc/ssh/sshd_config

###PermitRootLogin no
AllowUsers newuser guest psychotux hari
DenyUsers root

# /etc/init.d/sshd restart

Here users listed along with AllowUsers can be normal user or root equivalent.

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Check remote UDP connectivity from Linux

Hi there, You all know how to check TCP port connectivity from a Linux or UNIX machine to a remote machine using telnet as per th example below $ telnet 127.0.0.1 25 but we can't adopt TELNET to check UDP connectivity. Linux and most of the UNIXes come with a network layer utility called nc (abbreviation for netcat) which is very useful to check UDP connectivity and to explore a lot with both TCP and UDP. An example is shown below # nc -v -u -z -w 3 172.24.16.131 123 Connection to 172.24.16.131 123 port [udp/ntp] succeeded!

The best putty package available

Bored of Black screened Task bar filling putty? Issues with porting Saved sessions from machine to machine? Do you like tabbed SSH sessions? Start using portaputty instead of normal putty and link it with puttycm . Puttycm supports sessions to be saved in its own Database files. You can use the Putty sessions you have saved already right inside putty. You can have any number of databases which allow you to arrange Remote servers in folders and convenient namings. I personally recommend creating Database with puttycm rather than using the sessions saved in putty which doesn't offer any option to create folders and saving sessions under that directory tree. You can even save username/password to get it logged automatically and there is an option to pass commands to be run soon after login. I can't recommend this since some bug was found with these options. Portaputty is a variant of putty which stores all the Configuration data in text files instead of MS Window

PING.sh

#!/usr/bin/env bash ## Ping all machines in a Network PING="$(which ping) -c 1 -W 1" echo "Enter Subnet(eg:192.168.0)" read Subnet echo "Do you want to PING the entire network or a RANGE of IPs ? Enter your choice" echo 1. Ping Entire Network echo 2. Ping a RANGE read choice if [ $choice = 1 ]; then { echo Pinging..... for((i=1;i<255;i++)); do ${PING} ${Subnet}.${i} > /dev/null 2> /dev/null if [ $? -eq 0 ]; then echo -e "${Subnet}.${i} is up" fi done } fi if [ $choice = 2 ]; then { echo Enter the Starting IP of Range read a echo Enter the Last IP of Range read b echo Pinging..... for((i=$a;i<$b;i++)); do ${PING} ${Subnet}.${i} > /dev/null 2> /dev/null if [ $? -eq 0 ]; then echo -e "${Subnet}.${i} is up" fi done } fi exit 0

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