17th December 2001Tim Adye1 Using a Cable Modem at Home Tim Adye Particle Physics Department Rutherford Appleton Laboratory PPD Christmas Lectures 17 th December 2001

Tim Adye2 Home Internet Options Traditional dialup modem Maximum baud rate 56 kbits/s (often less) Can be unreliable Dialup times ~30s “Free” services available, but often heavily oversubscribed ISDN 64 kbits/s (can be doubled by using two lines) Fast dialup: ~1s Available anywhere ADSL 500/250 kbits/s (download/upload) Only available in some areas? Various companies

17th December 2001Tim Adye3 Home Internet Options Cable modem 512/256 kbits/s (cheaper 64 kbits/s option available) “Always on” Only available in some areas NTL and Telewest Cheapest “broadband” option, if available I have a 512 kbits/s NTL Cable Modem (Oxford). Everyone I know with broadband internet access has an NTL Cable Modem The rest of this talk is on this option only

17th December 2001Tim Adye4 Cable Modem Availability and Price NTL claims to be available in Abingdon, Bicester, Oxford, Wallingford, Wantage, Newbury, Reading Not everywhere in those areas Check you area at uses your postcode Could also check NTL Cable Modem cost £35/month (includes cable modem box rental); or £30/month + £149 (to buy cable modem box) Includes phone line Can also be combined with cable TV better deal if you have both Installation is £25

17th December 2001Tim Adye5 My experience of the NTL service Arranging for an engineer to call (installation or service) is really slow and frustrating Notoriously bad call centre NTL engineers were excellent Installed phone, cable TV, cable modem sockets just where I wanted them (at different ends of the house) Took a couple of hours Service has been pretty reliable ~4 overnight outages since February One longer problem Took several days to arrange for an engineer to call Fix was trivial (removing an attenuator on the coax cable) – now I know what to try

17th December 2001Tim Adye6 Installation Cable modem box Size of a large paperback (single edition LotR?) Coax cable to socket in the wall Socket does not need to be near TV/phone sockets Requires ethernet (10Base-T) or USB on your PC Works with Windows, Linux, or Mac I’ve only used Windows Brief tests with Manny’s Linux PC were unsuccessful USB only with Windows 98/ME/2000+ Supports DHCP, so software setup is simple just like a laptop at RAL Using more than one PC is complicated Even switching PCs isn’t trivial

17th December 2001Tim Adye7 Documentation NTL Documentation is really basic Usually enough to get you started It took me some time to discover more details Firewall configuration Transparent web cache Cable modem diagnostics Speed tests … until I discovered these excellent pages

17th December 2001Tim Adye8 Speed Bandwidth limited at 512 kbits/s download 128 kbits/s upload Could be slower if demand is heavy I usually see the full rate, but maybe Oxford is a luddite area

17th December 2001Tim Adye9 What it feels like With a 56kbits/s modem (usually connecting at 33 kbits/s) Convenient ssh connections to RAL/CERN/SLAC Unreliable connection could interrupt work at the wrong time Most X-Windows applications (eg. xterm, emacs) unusable PAW possible, but slow No problem downloading small files (up to ~1 MB) With cable modem Reliable ssh connections X-windows mostly OK xterm, emacs, PAW nearly as good as at RAL “Heavy” applications still sluggish, but many normally run locally, eg. Netscape, Acrobat No problem downloading medium-sized files (up to ~20 MB) Accessing PPD NT disk shares can still be slow 

17th December 2001Tim Adye10 Advantages of being “Always On” No dial up time No contention with phone Can run servers Allows access to your home machine from work Useful to pick up files you forgot to bring to work Can run ftp, web, login – I just use sshd IP address changes every few days, so need to use DNS service, eg. DNS2Go NTL forbid high bandwidth ftp/web servers

17th December 2001Tim Adye11 Security implications of being “Always On” Need to be more careful about security Hackers scan for security holes More chance they’ll find you if you are always connected, and have the same address Unless you really know what you’re doing, make sure you disable “File and printer sharing” (Windows) All unused inetd services (Linux) Consider setting up a firewall After trying several firewalls for Windows (eg. ZoneAlarm), I use Tiny Personal Firewall ( ) Virus checking is even more important

17th December 2001Tim Adye12 Accessing RAL RAL “internal” web pages and services are not directly available Eg. PPD internal page, RAL Information for Staff, PPD Unix systems, NT disk shares Sometimes there are alternatives RAL Notices can be accessed with a password ssh to csf and then to PPD Unix NT disks can be read via ftp You can also set up a “virtual private network” connection to RAL (AKA “PPTP”) …

17th December 2001Tim Adye13 Accessing RAL: VPN After logging in with your Federal ID/password, you tunnel “inside the firewall” See RAL PC Support pages (Network services : PPTP) NB. PC Support pages only accessible within RAL! Slower than a direct connection Also useful when at CERN, SLAC, etc.

17th December 2001Tim Adye14 Conclusions Once installed, cable modem is fast and reliable If you have £35/month to spare Be careful of hackers PPTP to RAL can be very useful