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New Contributor

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14 Messages

Sun, May 2, 2021 8:05 PM

Modem suddenly broadcasting SSDP packets (UPnP)

I keep a pretty close eye on my network and have noticed in the last couple days a new behavior I've not seen before. It seems like my Comcast modem (two different ones at different locations actually, both Technicolor) is started broadcasting SSDP packets:

22:15:33.468459 IP (tos 0x0, ttl 4, id 33878, offset 0, flags [DF], proto UDP (17), length 183)
    (a 169 LAN IP).50759 > (the 239 multicast IP).1900: UDP, length 155

etc etc. It's not shown here but they are coming from the MAC of the modem though I'm not sure why it's using that LAN IP block (I am trying obfuscating the actual IPs above because twice I've tried to post this and it keeps getting marked as "Private" but doesn't tell me why.)

Did Comcast push a firmware update and turn on something new and annoying? What is this thing doing?

Responses

Official Employee

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22 Messages

2 m ago

Hi there, ManChicken. Thanks for posting! It's possible an update could have gone through that may have caused this change. When you noticed this, did you notice any impact on your service? Are you noticing any new symptoms with your network, beyond the packets looking different?