Address Translation

Posted on 2000-02-07
Medium Priority
Last Modified: 2010-03-18
I am running RedHat 6.1 with 2 LAN cards, ipchains & Masq. through the cards to the internet.  I need to open a port comming in to see my Web Server on my internal network.  How do I do this?

Please help.
Question by:byrona
  • 3

Author Comment

ID: 2499824
Edited text of question.

Expert Comment

ID: 2506906
1) Go to Linuxconf
2) Select firewall
3) Select forwarding
4) Select IP Masquerade
5) From <internal net no>, mask <internal net mask> Interface Any
6) To, Interface Any

Make sure you setup the network cards correctly and can ping outside from the Linux before you go for the steps

You can add the "firewall" module in linuxconf under:

Control -> Control File ans System -> Configure Linuxconf Modules

Then next time you will see it under:
Config -> networking -> server tasks


Author Comment

ID: 2511382

Thank you for the answer.  It is not what I am looking for or maybe I do not understand.

On my eth0 I am on the local network and on eth1 I am on the internet (i.e plugged into my router). I need to point a port comming from outside into my local network to an WebServer that has got an illegal IP Address. (eg if I type I want it to go to on my local network.

I am not to sure why the from has got the internal network number and not the external?  This may be where I am going wrong.

Please can u help me further with this.

Author Comment

ID: 2530077
Is there nobody that can do this out there?

Accepted Solution

redhat2 earned 800 total points
ID: 2533566
This is so easy!

Download the package ftp://www.mirror.ac.uk/sites/ftp.redhat.com/pub/contrib/libc6/i386/ipmasqadm-0.4.2-3.i386.rpm
1) Install this package with "rpm -i ipmasqadm-0.4.2-3.i386.rpm"
2) Create a file called /etc/rc.d/rc.firewall containing this ---

/sbin/depmod -a
/sbin/modprobe ip_masq_ftp
/sbin/modprobe ip_masq_raudio
/sbin/modprobe ip_masq_irc
/sbin/modprobe ip_masq_quake
/sbin/modprobe ip_masq_quake 26000,27000,27910,27960
/sbin/modprobe ip_masq_cuseeme
/sbin/modprobe ip_masq_vdolive

#CRITICAL:  Enable IP forwarding since it is disabled by default since
# Redhat Users:  you may try changing the options in /etc/sysconfig/network from:
#   FORWARD_IPV4=false
#    to
#   FORWARD_IPV4=true
echo "1" > /proc/sys/net/ipv4/ip_forward

# Dynamic IP users:
#   If you get your IP address dynamically from SLIP, PPP, or DHCP, enable this following
#  option.  This enables dynamic-ip address hacking in IP MASQ, making the life
#  with Diald and similar programs much easier.
#echo "1" > /proc/sys/net/ipv4/ip_dynaddr
/sbin/ipchains -M -S 7200 10 160

/sbin/ipchains -P forward DENY
#This line will forward traffic from your internal network to the outside MASQed
/sbin/ipchains -A forward -s -j MASQ

#echo "Enabling IPPORTFW Redirection on the external LAN.."
/usr/sbin/ipmasqadm portfw -f
/usr/sbin/ipmasqadm portfw -a -P tcp -L 9000 -R 80

#End of rc.firewall

3) make the file executable using the command "chmod 750 /etc/rc.d/rc.firewall"
4) edit the file /etc/rc.d/rc.local using "vi /etc/rc.d/rc.local"
5) press these keys exactly, press esc, ":", 7000, "Insert", /etc/rc.d/rc.firewall, esc, ":wq"
NOTE: If you have trouble with vi, email me and I can help..., also try kedit or emacs or any other text editing program
6) Now reboot your computer... Test and see if you can get into the webserver from the outside, you should be able to.
7) If you have trouble with this, http://members.home.net/ipmasq/ipmasq-HOWTO-1.81.html might help you, also post what you can and can not do as part of the rejection.

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