If you are flying in to Asmara, you will need a permit from the Tourist Bureau on Liberation Avenue if you consider traveling outside Asmara's city limits. This permit needs to be applied for 10 days before travel. There are very few places other than Asmara, Keren and Massawa/Dahlak Islands that foreigners can travel to as of January 2010 other than those on a designated mission working with the Eritrean government. If you are coming by land or ferry/private boat to Massawa, you can get a travel permit at the locality of your arrival, to transit the country, given you have a valid entry visa to Eritrea. As long as you notify and consult with the Eritrean mission issuing your entry visa about your point of entry and travel plans well ahead of time, getting the travel permit is no problem.
The most common form of intercity transportation in Eritrea is bus and/or minibus. The most frequent services, consisting of several buses/minibuses a day run between Asmara and Keren, Asmara and Massawa as well as between Asmara and the towns of the southern highlands such as Debarwa, Mendefera, Adi Quala as well as Dekemhare, Segeneiti, Adi Caieh and Senafe reaching the Ethiopian border. It is not possible for foreign nationals to approach the Ethiopian border and travel beyond the towns of Senafe and Adi Quala as it is a heavily militarized warzone. There are also daily bus services on the road between Teseney On the Sudanese border close to Kassala and Asmara traversing Barentu, Agordat and Keren as well as an alternative route traversing Barentu and Mendefera. Once a day, buses/minibuses also run between Asmara and some of the villages of the southern highlands as well. Buses to the north of the country Nakfa are less frequent and travel between once weekly to a couple of times weekly between Asmara and Nakfa traversing Keren and Afabet. The buses to the southern coast Assab from Asmara are equally infrequent, once weekly only, traversing Massawa. Tickets are bought on the bus and a first-come-first-served rule applies. Some state-run bus lines traveling to remote frontier areas do allow for tickets to be bought in advance at the Asmara bus station, where you can also inquire about the bus-schedule. There will always be some people who speak English and are more than willing to help translate.
Nasair connects Asmara with remote Assab twice weekly, and it flies between Asmara and Massawa twice weekly. However the latter flight route may not be a necessary option since the distance between the latter two cities is only 120 km 75 mi along one of Eritrea's best and most scenic roads. There are also buses several times a day running between the two cities, which cost a fraction of the flight and take little more than two hours while making time for refreshing stops in the mountains.
The only rail line in Eritrea runs between Asmara and Massawa, and it is only served by a museum railway steam engine and all with currently no regular service except for freight. It only caters to chartered tour groups, and it takes a daunting 5 hours to complete just the one way journey.