Does an internation student on student visa in uk need a visa to visit Ireland for 3-4 days?

No ,just passport.

You will need an Irish visa.

hallo, visa is required for you. contact the Irish embassy in the UK Ireland Embassy , United Kingdom 17 Grosvenor Place London United Kingdom SW1X 7HR Phone: +44-20-72352171 Fax: +44-20-72356961 Ireland Consulate , United Kingdom Montpelier House, 106 Brompton Road London United Kingdom SW3 1JJ Phone: +44-20-72257700 Fax: +44-20-72357777/8 Ireland Consulate , United Kingdom 16 Randolph Crescent Edinburgh United Kingdom EH3 7TT Phone: +44-131-2267711 Fax: +44-131-2267704 Ireland Consulate , United Kingdom Brunel House, 2 Fitzalan Road Cardiff United Kingdom CF24 0EB Phone: +44-29-20662000 Fax: +44-29-20662006

Yes

Depends on your passport. There is something called the "Free Travel Area", but the Garda (Irish Police) still checks uninformed non EU citizens. You can be on the safe side and get a visa, you can just say "I'm flying from the UK" and the officer SHOULD (no guarantee) let you pass.... but your best bet, if you want to avoid the hassle is: take a flight to Northern Ireland and from there a bus to Newry and then a taxi to Dundalk, or ask for a ride. You can obviously take a bus/train to Dublin but you might get checked, while cars are never checked across the border, simply because there is no physical border.