How to redirect port using IPTABLES
You can redirect the port in IPTABLES using the prerouting parameter.
Following is the command you can use to redirect the traffic of port 8080 to port 80.
$ /sbin/iptables -t nat -I PREROUTING -p tcp –dport 8080 -j REDIRECT –to-port 80
$ /etc/init.d/iptables save
$ /etc/init.d/iptables restart
You can change the ports in the above command according to your need.
Tcpdump command to monitor the SMTP activity from a IP or range of IP.
The tcpdump is a useful utility to monitor the network activity in the server.
You can monitor the SMTP activity to find out the mail account used by spammer.
tcpdump -i eth0 -n src 192.168.1.4 \or dst 192.168.1.4 -w smtp.tcpdump -s 2048
The above command will monitor the SMTP activity from the IP address 192.168.1.4 and will log to the file smtp.tcpdump.
Please use the following command to monitor a range of IP
tcpdump -i eth0 -n src net 219.91.0.0/16 \or dst net 219.91.0.0/16 -w smtp.tcpdump -s 2048
The above command will monitor the range of IP starting with 219.91. You can use less or Wireshark to analyze the dump file. You need to replace the network device with your network device EG : venet0:0 in a VPS.
Basic Requirements for cpgsd
* gcc
* Perl 5+
* OpenSSL (including headers, usually in a separate package called something like openssl-devel or ssl-dev)
* Net::SSLeay perl module
* IO::Socket::SSL perl module
* IPC::Run perl module
configure the sshd server to disable password login and enable keys.
First - We need to generate a pair of keys.
ssh-keygen -v -t rsa -b 2048
and then
cat /home/buddy/.ssh/buddy_rsa.pub > /home/buddy/.ssh/authorized_keys
Editing the config file /etc/ssh/sshd_config
login to remote server using the password to configure the sshd server to disable password login and enable keys.
And then edit…
PermitRootLogin no
#Disable Login password
#PasswordAuthentication no
ChallengeResponseAuthentication no
#Allow forwarding yes
AllowTcpForwarding no
# Uncomment ‘PasswordAuthentication no’ line only after making sure that the key authentication is working properly.
# Disabling root login is recommended anyway, though not useful after disabling login password.
# Allow forwarding is not recommended for multi user hosting envirnoment where keys could be exposed. Anyway, we should only allow it if we intend to forward keys from server to server but keep all our keys on the local machine.
SSH tunnel for Mysql
This will open a tunnel, listening on localhost:3308 and forwarding everything to yourdomain.com:3306
ssh -L 3308:yourdomain.com:3306 username@yourdomain.com
And then
mysql -u username -p -h 127.0.0.1 -P 3308 databasename
