2011/5/17 Aleksey Tsalolikhin atsaloli.tech@gmail.com:

[root@hwdltsaloli ~]# cat /etc/sysconfig/iptables # Firewall configuration written by system-config-securitylevel # Manual customization of this file is not recommended. *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] :RH-Firewall-1-INPUT - [0:0] -A INPUT -j RH-Firewall-1-INPUT -A FORWARD -j RH-Firewall-1-INPUT -A RH-Firewall-1-INPUT -i lo -j ACCEPT -A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT -A RH-Firewall-1-INPUT -p 50 -j ACCEPT -A RH-Firewall-1-INPUT -p 51 -j ACCEPT -A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT -A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited COMMIT

http://en.wikipedia.org/wiki/IPsec ?

-- Eero

Hi,

On Tue, 2011-05-17 at 11:13 -0700, Aleksey Tsalolikhin wrote:

[root@hwdltsaloli ~]# cat /etc/sysconfig/iptables # Firewall configuration written by system-config-securitylevel # Manual customization of this file is not recommended. *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] :RH-Firewall-1-INPUT - [0:0] -A INPUT -j RH-Firewall-1-INPUT -A FORWARD -j RH-Firewall-1-INPUT -A RH-Firewall-1-INPUT -i lo -j ACCEPT -A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT -A RH-Firewall-1-INPUT -p 50 -j ACCEPT -A RH-Firewall-1-INPUT -p 51 -j ACCEPT -A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT -A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited COMMIT [root@hwdltsaloli ~]# lsof -i:50 [root@hwdltsaloli ~]# lsof -i:51 [root@hwdltsaloli ~]#

/etc/services says:

re-mail-ck 50/tcp # Remote Mail Checking Protocol re-mail-ck 50/udp # Remote Mail Checking Protocol

la-maint 51/tcp # la-maint 51/udp # IMP Logical Address Maintenance

Google turns up RMCP is a simple lightweight DP protocol for checking if you have mail on a server

A quick Google search failed to turn up what is "IMP Logical Address Maintenance"

The -p you are referring to is NOT a port, but a protocol (number), 50 and 51 stand for IPSEC protocols (AH and ESP).

[michel@deltaflyer ~]$ cat /etc/protocols | grep 51 ah 51 AH # Authentication Header ipv6-auth 51 IPv6-Auth # Authentication Header for IPv6 (not in official list) [michel@deltaflyer ~]$ cat /etc/protocols | grep 50 esp 50 ESP # Encap Security Payload ipv6-crypt 50 IPv6-Crypt # Encryption Header for IPv6 (not in official list)

Please read 'man iptables' :)

Regards,

Michel