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Full Discussion: 3 public servers: middle machine for traffic forwarding
Special Forums IP Networking 3 public servers: middle machine for traffic forwarding Post 303008256 by pedroz on Wednesday 29th of November 2017 10:36:31 AM
Old 11-29-2017
3 public servers: middle machine for traffic forwarding
With the following machines...
Server 1: PPTP client windows; Public IP: 1.1.1.1
Server 3: PPTP server centos6; Public IP: 3.3.3.3
Connecting VPN server3 from server1 works correctly!

Goal is to have a middle server forwarding traffic in both ways
Server 1: PPTP client windows; Public IP: 1.1.1.1
Server 2: Traffic forwarding centos6; Public IP: 2.2.2.2
Server 3: PPTP server centos6; Public IP: 3.3.3.3

Server1 connects with PPTP client to 2.2.2.2 and this server2 redirects to 3.3.3.3 (server3)
Is it possible to have that scenario?


Tried the following setup in Server2
1. Routing enabled
Code:
# echo "1" > /proc/sys/net/ipv4/ip_forward
# nano /etc/sysctl.conf
net.ipv4.ip_forward = 1
# sysctl -p

2. Iptables forward
Code:
# iptables -F -t nat
# iptables -F
# iptables -A FORWARD -d 3.3.3.3 -i eth0 -j ACCEPT
# iptables -t nat -A PREROUTING -i eth0 -d 2.2.2.2 -j DNAT --to-destination 3.3.3.3
# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
# iptables save
# iptables reload

When trying to connect with Server1 VPN PPTP client to 2.2.2.2, it redirects correctly to 3.3.3.3.
However, in server3 (3.3.3.3) it does not assign a PPTP client to 2.2.2.2.
Here is the connection log at server3

Code:
# tail -f /var/log/messages
Nov 29 09:53:39 office pptpd[2121]: CTRL: Client 2.2.2.2 control connection started
Nov 29 09:53:39 office pptpd[2121]: CTRL: Starting call (launching pppd, opening GRE)
Nov 29 09:53:39 office pppd[2122]: Plugin /usr/lib64/pptpd/pptpd-logwtmp.so loaded.
Nov 29 09:53:39 office pppd[2122]: pppd 2.4.5 started by root, uid 0
Nov 29 09:53:39 office pppd[2122]: Using interface ppp2
Nov 29 09:53:39 office pppd[2122]: Connect: ppp2 <--> /dev/pts/3
Nov 29 09:54:09 office pppd[2122]: LCP: timeout sending Config-Requests
Nov 29 09:54:09 office pppd[2122]: Connection terminated.
Nov 29 09:54:09 office pppd[2122]: Modem hangup
Nov 29 09:54:09 office pppd[2122]: Exit.
Nov 29 09:54:09 office pptpd[2121]: GRE:  read(fd=6,buffer=6124a0,len=8196) from PTY failed: status = -1 error =  Input/output error, usually caused by unexpected termination of pppd,  check option syntax and pppd logs
Nov 29 09:54:09 office pptpd[2121]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
Nov 29 09:54:09 office pptpd[2121]: CTRL: Client 2.2.2.2 control connection finished

Any ideas to setup the server2 working as middle traffic forwarder?
 

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LEARN ABOUT SUSE

pppd-radius

PPPD-RADIUS(8)						      System Manager's Manual						    PPPD-RADIUS(8)

NAME

       radius.so - RADIUS authentication plugin for pppd(8)

SYNOPSIS

       pppd [ options ] plugin radius.so

DESCRIPTION

       The  RADIUS  plugin for pppd permits pppd to perform PAP, CHAP, MS-CHAP and MS-CHAPv2 authentication against a RADIUS server instead of the
       usual /etc/ppp/pap-secrets and /etc/ppp/chap-secrets files.

       The RADIUS plugin is built on a library called radiusclient which has its own configuration files (usually in  /etc/radiusclient),  consult
       those files for more information on configuring the RADIUS plugin

OPTIONS

       The RADIUS plugin introduces one additional pppd option:

       radius-config-file filename
	      The  file  filename  is  taken  as  the  radiusclient  configuration  file.   If	this  option  is  not  used,  then the plugin uses
	      /etc/radiusclient/radiusclient.conf as the configuration file.

       avpair attribute=value
	      Adds an Attribute-Value pair to be passed on to the RADIUS server on each request.

       map-to-ifname
	      Sets Radius NAS-Port attribute to number equal to interface name (Default)

       map-to-ttyname
	      Sets Radius NAS-Port attribute value via libradiusclient library

USAGE

       To use the plugin, simply supply the plugin radius.so option to pppd, and edit /etc/radiusclient/radiusclient.conf appropriately.   If  you
       use  the  RADIUS  plugin,  the  normal  pppd authentication schemes (login, checking the /etc/ppp/*-secrets files) are skipped.	The RADIUS
       server should assign an IP address to the peer using the RADIUS Framed-IP-Address attribute.

SEE ALSO

       pppd(8) pppd-radattr(8)

AUTHOR

       David F. Skoll <dfs@roaringpenguin.com>

																    PPPD-RADIUS(8)
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