From a distance, the cluster of mud huts that cling to the side of a mountain gorge high above the Asam River would hardly appear to be a major military center.

Only the armed sentries posted along the narrow trail leading toward the settlement and the barely visible profile of antiaircraft guns perched high above it that there is something different about the village of Torabora. The heavily guarded enclave is the command center for one of the biggest groups of Islamic fighters operating inside Afghanistan, the Hezbi Islami led by Younis Khalis.

"Torabora's our Kabul," one insurgent leader said with pride. In addition to a command and disbursement center, Torabora serves as the group's only medical aid station in the area and a modest supply staging area.

Although Torabora is barely 25 miles south of major Soviet and Afghan Army troop concentrations at Jalalabad, the steep, narrow Asam River gorge protects the village from ground assault.

Repeatedly attacked from the air by helicopter gunships and Soviet Mig fighter jets, Torabora survives, much as the insurgency itself, despite the enemy's superior firepower.

The few minutes' advance warning of an attack given by the sound of advancing aircraft is all that is necessary for the 200 guerrillas living at Torabora to take shelter among the boulders and crevasses that cover the mountainside.

During a recent raid, several mud and rock huts were destroyed, but no one was killed. New huts were quickly built nearby and work at Torabora resumed.

Recently, the group substantially beefed up Torabora's air defenses by adding a pair of twin-barreled 20mm antiaircraft batteries to the existing three Chinese-made 14.5-mm guns. One of the batteries, obviously new, had just been installed and test-fired. Thirteen cases of ammunition were stacked in a small cave 20 yards away.

"Next time it will be a bit harder for them," said Abdul Khayum, 30, the former geography teacher who commands the outpost.

Apart from the weaponry, there is little hardware at Torabora more sophisticated than a tailor's portable sewing machine. Consequently, there is virtually nothing here that cannot easily be replaced other than the lives of the troops.

This rudimentary nature of operating, which is characteristic of the entire Afghan insurgency, is what makes it so difficult for the Soviets to combat, even with the most modern weaponry.

Khayum communicates with his field leaders by messengers. The ability of these runners to traverse the rugged Afghan terrain like mountain goats makes this communications system relatively efficient and virtually impossible for the Soviets to intercept.

But aside from the small packets of message paper carefully covered in waterproof wrapping carried by most commanders, there are few official documents or other secret communications at the guerrilla headquarters.

Khayum lives and works from a dimly lit 15-by-20-foot hut, headed by a wood stove. Sitting on the blanket-covered floor, he talks with his colleagues and dispatches an occasional message.

As with many leaders of the Afghan insurgency, there is little in Khayum's dress or bearing to distinguish him as a leader. Privilege and protocol do not accompany Afghan rebel commands.

The total absence of women in the village, the roughly constructed mud structures and disheveled Mujaheddin (Freedom Fighters) who live in them, create an atmosphere more in keeping with an outlaw gang's mountain hideout than a military command center.

The ground is strewn with the litter of war: empty, rusting ammunition tins with Soviet markings, broken wooden boxes that once contained hand grenades and an occasional spent rocket round from a previous air attack.

Much of the debris, however, is put to use. At the cookhouse, ventilated as much by ragged holes from Soviet air strikes as by the few carefully constructed vents, the baker shapes coarse, unleavened bread on an overturned wooden ammunition box.

Other ordnance containers serve as crude legs for the tailor's work platform and medicine chests for Torabora's resident doctor, a 24-year-old Kabul University graduate named Mahmud Kadir.

Kadir trained for three months at the group's main hospital in Peshawar before coming to Torabora last year. Now with a modest assortment of medicines ranging from Vitamin B complex injections to Valium, antibiotics and disinfectants, he treats patients on a blanket spread over the dirt floor of his small hut.

During a three-day period early last week, the young physician removed shrapnel from the leg of one insurgent soldier, stitched up gashed fingers and dispensed several containers of medicine.

"Many people simply have colds," he explained. A lack of equipment prevents him from dealing effectively with serious wounds. With more comprehensive medical treatment available only in Pakistan, an arduous march away even for a healthy man, few with such injuries survive. Most ingredients for the adequate but spartan diet of bread and vegetables are grown locally in terraced fields around Torabora. Sugar and tea, the two mainstays of the Afghan diet, plus occasional luxuries such as Kyayum's filter-tip cigarettes, come by donkey from the bazaars in government-controlled Jalalabad.

Between air attacks, time passes slowly here. Daily working parties go out in search of wood, Torabora's only heating and cooking fuel. Prayers and group readings from the Koran take up much of the early evening hours. Later in the evenings, guerrillas cluster around the few pocket transistor radios in the village.

Invariably these radios are tuned into a special frequency, apparently beamed from Pakistan, which chronicles the guerrillas' successes in other parts of Afghanistan.

But by 9 p.m., most radios are silent and Torabora's handful of kerosene lamps have been snuffed out. Then the only sound is that of the Asam River roaring through the gorge hundreds of feet below as the command post rests in preparation for predawn prayers and another day of war.