Recognized

So, get up now wise Eurykleia, and wash the feet of one of like age to your king! Even such as his are this man's feet, and even such are his hands.

Penelope must have recognized Odysseus because of this:
Penelope really appreciates Odysseus's words and information and offers to get his feet washed and a bed to sleep on. Odysseus asks for a wise and old lady to wash his feet. Penelope then turns to an old slave woman who nourished and suckled Odysseus as a child to do so and says:

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Eurykleia recognizes Odysseus

Despite Odysseus' disguise Penelope has determent his real age. And she asks the old slave woman who knows Odysseus the best to 'check him out'. Although it isn't her usual task, Eurykleia did approach Odysseus and says:

Many long-suffering strangers have come here, but not ever do I think I have seen a man so like another as you are like Odysseus in your stature, your voice, and in the shape of your feet.

She washed him, coming close to her king, and immediatly she recognized the scar, which once a boar had driven in with his white tusks when he went to Parnassos, to Autolykos.

Then Eurykleia is taking hold of Odysseus chin.

Eurikleia glanced over to Penelope.

Truly you are Odysseus, my child!

Meaning that Penelope was wise enough not to make contact with Eurykleia and avoided that Eurykleia would speak out about it and so did Odysseus. He seized her by the throat and pulled her in close:

But Penelope could not see here, nor understand, because Athena had turned her thoughts aside.

Old lady, why do you want to destroy me? You yourself nursed me at your tit. Now after suffering many pains I have returned in the twentieth year to the land of my fathers. But because you have found out and a god has placed this in your heart- keep quiet!
Let no one else in these halls take notice.

Now both leading women of the house know that Odysseus has returned. And that they can not reveal this fact to the others. The slaves are still close by, cleaning the hall after the suitors left. Eurykleia replies:

If some god allows you to overcome the bold suitors, then I will tell you in detail which women in the halls dishonner you, ....