There are at the approaches of Medina angels so that plague and the Dajjal shall not penetrate into it.  

قَالَ رَسُولُ اللَّهِ ﷺ عَلَى أَنْقَابِ الْمَدِينَةِ مَلاَئِكَةٌ لاَ يَدْخُلُهَا الطَّاعُونُ وَلاَ الدَّجَّالُ  

Dajjal will come from the eastern side with the intention of attacking Medina until he will get down behind Uhud. Then the angels will turn his face towards Syria and there he will perish.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ يَأْتِي الْمَسِيحُ مِنْ قِبَلِ الْمَشْرِقِ هِمَّتُهُ الْمَدِينَةُ حَتَّى يَنْزِلَ دُبُرَ أُحُدٍ ثُمَّ تَصْرِفُ الْمَلاَئِكَةُ وَجْهَهُ قِبَلَ الشَّامِ وَهُنَالِكَ يَهْلِكُ