IBM Certification Study Guide AIX V4.3 System Support

12.2 Setting Up the PPP Control Link

12.3 Assigning the PPP IP Addresses

The following information is needed for this procedure: the IP address, gateway, and netmask for the host.

To get this information do the following:

Enter smitty tcpip
Select Minimum Configuration & Startup.
Choose the Available Network Interface, such as en0 or tr0.
Make note of the information required.

For the purposes of this discussion, the settings you will use are:

Hostname: mickey
Internet Address: 9.3.1.45
Network Mask: 255.255.255.0
Nameserver: 9.3.1.74
DOMAIN Name: itsc.austin.ibm.com
GATEWAY Address: 9.3.1.74

You will need to do the following:

Choose an unused address in the same domain: 9.3.1.46.
Add an entry in the /etc/hosts file with the new address and hostname for the PPP client.
Add the PPP addresses by entering the command smitty ppp.
Choose the option PPP IP Interfaces.
Choose the option Add a Server Interface.
Fill in the fields, shown in Figure 114, with information provided previously.

Figure 114: PPP IP Configuration
Press Enter to add the IP Server configuration. This creates a file entry in /etc/ppp/if_conf. The file can be viewed using the following:
```
# cat /etc/ppp/if_conf
interface
server
local_ip 9.3.1.45
remote_ip 9.3.1.46
netmask 255.255.255.0
```
Make sure ipforwarding is on. By default in AIX 4, ipforwarding is turned off. If you want your server to act as a router, you need to turn ipforwarding on. Check the value of ipforwarding with:
```
# no -a |grep ipf
                ipfragttl = 60
             ipforwarding = 0
```
If ipforwarding is 0, change it to 1 with:
```
no -o ipforwarding=1
```

Because you are adding the client to the same subnet as the server, you will want the server to respond to arp requests from other hosts in the network, so that all traffic to the client will get routed through the hosts. You can do this with a proxy arp.

Find the hardware address of the local adapter for the client using:


# netstat -i
Name  Mtu   Network     Address            Ipkts Ierrs    Opkts Oerrs  Coll
lo0   16896 link#1                          203625     0   203773     0     0
lo0   16896 127         loopback            203625     0   203773     0     0
lo0   16896 ::1                             203625     0   203773     0     0
en0   1500  link#2      2.60.8c.2f.47.42    712193     0   712606     0     0
en0   1500  9.3.5       goofy_en0           712193     0   712606     0     0
tr0   1492  link#3      10.0.5a.a8.3b.fa   1088842     0   769364     0     0
tr0   1492  9.3.1       goofy              1088842     0   769364     0     0
tr1   1492  link#4      10.0.5a.a8.d1.f3   1076155     0   726539     0     0
tr1   1492  9.3.4       goofy_stby         1076155     0   726539     0     0

Add an arp entry for the remote host using:

arp -s type hostname hardware address pub

where:

type: The type of your network adapter. Valid types are: ether, 802.3, fddi, 802.5 (token ring).
hostname: Hostname of the client.
hardware address: From netstat -i. Use colon separators.
pub: Indicates public and permanent.

The token ring (tr0) hardware address is used for this example.

For server mickey, this command is:

arp -s 802.5 goofy 10:0:5a:8c:3b:fa pub

Verify the arp entries with an arp -a command, the output is as follows:

goofy (9.3.1.46) at 10:0:5a:8c:3b:fa [token ring] permanent published

12.4 Adding a PPP Login User