You can create URL redirection service for your blog within five minutes using nothing but web server’s mod_redirect module. For example, when you type or share a url io9.in/t/5159 you will be automatically redirected to http://www.cyberciti.biz/tips/my-10-unix-command-line-mistakes.html. In this quick post I will explain how to create url shortener and integrate your wordpress based blog without installing any new scripts.
SMTP is used to send mail. Sendmail, Qmail, Postfix, Exim etc all are used on Linux as mail server. Mail server uses the TCP port 25. Following two iptable rule allows incoming SMTP request on port 25 for server IP address 188.8.131.52 (open port 25):
iptables -A INPUT -p tcp -s 0/0 –sport 1024:65535 -d 184.108.40.206 –dport 25 -m state –state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p tcp -s 220.127.116.11 –sport 25 -d 0/0 –dport 1024:65535 -m state –state ESTABLISHED -j ACCEPT
In order to block port 25 simply use target REJECT instead of ACCEPT in above rules.
And following two iptables rules allows outgoing SMTP server request for server IP address 18.104.22.168:
iptables -A OUTPUT -p tcp -s 22.214.171.124 –sport 1024:65535 -d 0/0 –dport 25 -m state –state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -p tcp -s 0/0 –sport 25 -d 126.96.36.199 –dport 1024:65535 -m state –state ESTABLISHED -j ACCEPT
You would like to block outgoing access to particular remote host/ip or port for all or selected service/port. In this quick tutorial I will explain how to use iptables to block outgoing access.
So how do you set DNS namserver under Sun Solaris UNIX system? The resolver is a set of routines in the C library that provide access to the Internet Domain Name System (DNS). The resolver configuration file contains information that is read by the resolver routines the first time they are invoked by a process. The file is designed to be human readable and contains a list of keywords with values that provide various types of resolver information.
Internet address (in dot notation) of a name server that the resolver should query. Up to MAXNS (currently 3, see ) name servers may be listed, one per keyword. If there are multiple servers, the resolver library queries them in the order listed. To configure Solaris nameserver edit or modify /etc/resolv.conf file.
DNS Client Setup
First Create the file called /etc/resolv.conf – which includes the primary and secondary DNS server IP address for Solaris system, it can be your own DNS server or your ISPs DNS server:
# touch /etc/resolv.conf
Open /etc/resolv.conf using vi text editor:
# vi /etc/resolv.conf
Add the following lines to it:
- nameserver IP : It is IP of first DNS server
- search nixcraft.in : Default domain name to search. For example, if you type command nslookup www, it will search it as www.nixcraft.in
2) Enable the name resolving using DNS as follows:
# cp /etc/nsswitch.dns /etc/nsswitch.conf
3) Test new name server by running the nslookup command as follows:
# nslookup nixcraft.in
# /usr/sfw/sbin/nslookup nixcraft.in