Centos 6: csf blocking whois

symptom:

# whois google.com

[Querying whois.verisign-grs.com]

[Unable to connect to remote host]

To solve this problem, edit /etc/csf/csf.conf, make sure outgoing to port 43 and 53 are allowed.

# vi /etc/csf/csf.conf

...

# Allow outgoing TCP ports

TCP_OUT = "20,21,22,25,43,53,80,110,113,443,587,993,995"

...

# Allow outgoing UDP ports

# To allow outgoing traceroute add 33434:33523 to this list

UDP_OUT = "20,21,43,53,113,123"

...

Restart your csf

# csf -r

Done!