Thanks for the reply BuckWeet. Re trojans, no, all PCs run bang up-to-date antivirus software, so I'm sure that's not the answer. Also, having used the internet, I could disconnect the cable between hub and router, and the connection would stay up indefinitely. Here's my current config:-
Current configuration:
!
version 12.0
no service pad
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname ROUTER
!
logging buffered 8192 debugging
enable secret 5 xxxxxxxxxxxxxxxxxxxxxxxxxxxxx.
!
username ROUTER password 7 xxxxxxxxxxxx
!
!
!
!
ip subnet-zero
no ip source-route
!
ip name-server 194.152.64.34
ip name-server 194.152.64.35
ip name-server 194.152.64.68
isdn switch-type basic-net3
!
!
process-max-time 200
!
interface Ethernet0
ip address 10.150.120.154 255.255.255.0
ip access-group 121 in
no ip directed-broadcast
no ip proxy-arp
ip nat inside
!
interface BRI0
no ip address
no ip directed-broadcast
encapsulation ppp
dialer pool-member 1
isdn switch-type basic-net3
ppp authentication chap pap callin
!
interface Dialer1
description ISP
ip address negotiated
ip access-group 121 in
no ip directed-broadcast
no ip proxy-arp
ip nat outside
encapsulation ppp
no ip split-horizon
dialer remote-name Cisco1
dialer idle-timeout 119
dialer string xxxxxxxxxxx class DialClass
dialer hold-queue 10
dialer pool 1
dialer-group 1
pulse-time 0
ppp authentication chap pap callin
ppp chap hostname fred.bloggs.co.uk
ppp chap password 7 xxxxxxxxxxxx
ppp pap sent-username fred.bloggs.co.uk password 7 xxxxxxxxxxxx
!
ip nat inside source list 18 interface Dialer1 overload
no ip http server
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer1
!
!
map-class dialer DialClass
access-list 18 permit 10.0.0.0 0.255.255.255
access-list 121 deny udp any eq netbios-dgm any
access-list 121 deny udp any eq netbios-ns any
access-list 121 deny udp any eq netbios-ss any
access-list 121 deny tcp any eq 137 any
access-list 121 deny tcp any eq 138 any
access-list 121 deny tcp any eq 139 any
access-list 121 permit ip any any time-range TIME
dialer-list 1 protocol ip permit
!
line con 0
exec-timeout 0 0
transport input none
stopbits 1
line vty 0 4
exec-timeout 0 0
login local
!
time-range TIME
periodic daily 0:00 to 23:59
!
end
Note that dialer idle-timeout is currently set to 119, which is the highest setting that appears to "stay" in the config, and that will drop the line satisfactorily. The router interface configuration will accept my original time of 300 seconds when it's typed in, but after saving with "running-config startup-config", the "dialer idle-timeout" line no longer appears in the "show run" config listing, and line stays up indefinitely.
ROGER - GØAOZ.