Luke 22:31-32
And the Lord said, “Simon, Simon! Indeed, Satan has asked for you, that he may sift you as wheat. But I have prayed for you, that your faith should not fail; and when you have returned to Me, strengthen your brethren.”

I always found it interesting when Jesus tells Peter that “Satan has asked for you.”
This has deep overtones of Job, where Satan asked to touch his life to get him to turn against God.
Does Satan need permission to go after someone?
In Luke 8 is a multi-demon possess man is free by Jesus. I cannot imagine God giving permission for multiple demons to attack someone.
So perhaps Satan needs permission for only believers.
Regardless of the answer, Peter would later say, “Be sober, be vigilant; because your adversary the devil walks about like a roaring lion, seeking whom he may devour. Resist him, steadfast in the faith, knowing that the same sufferings are experienced by your brotherhood in the world.” 1 Peter 5:8-9
What Peter faced in the hours before the crucifixion of Jesus is the same type of temptation others face around the world.
Satan seeks to devour your faith.
Jesus told Peter, “I have prayed for you, that your faith should not fail!”
Jesus seeks the best for you while Satan is a liar and murderer and wants the worse for you.
I like the final words Jesus said to Peter, “When you have returned to Me, strengthen your brethren.”
Those tempted by Satan to sin, and Peter did, learn a lesson of failure.
Repentance, which Peter did, gives a lesson of faith and strength you can share and help others with.