NextTrace: How to Check a VPS Route to China

Install NextTrace

NextTrace is open source under the GPL-3.0 license. Its README gives these install commands:

System	Command
macOS	brew install nexttrace
Linux, macOS or BSD	curl -sL https://nxtrace.org/nt | bash
Debian or Ubuntu	add NextTrace’s APT repository, then sudo apt install nexttrace
Arch Linux	yay -S nexttrace-bin
Windows	winget install nexttrace, or scoop bucket add extras && scoop install extras/nexttrace

Prebuilt downloads are at nxtrace.org/downloads. Homebrew had version 1.7.4 on October 12, 2026.

Permissions differ by system. The README says that on macOS “only ICMP mode does not require elevated privileges”, so TCP and UDP traces need sudo. Our ICMP traces on macOS 14 ran without it, although Homebrew’s install note says to run NextTrace with sudo. On Windows, which the README calls experimental, normal users get ICMP only, and TCP or UDP traces need Administrator mode with WinDivert.

Read the output

This is a shortened trace we ran on October 12, 2026, from a Globalping probe on a China Telecom line in Guangzhou to a DMIT server in Los Angeles. The probe’s own network hops are left out.

 4  14.147.135.197   AS4134  [CHINANET-GD]    Guangzhou, China
 6  183.56.34.37     AS4134  [APNIC-AP]       Guangzhou, China
 7  202.97.43.78     AS4134  [CHINANET-BB]    Guangzhou, China       7.04 ms
 8  59.43.16.166     *       [CN2-BackBone]   Guangzhou, China
 9  59.43.181.94     *       [CN2-BackBone]   Guangzhou, China       8.30 ms
10  59.43.182.73     *       [CN2-BackBone]   Los Angeles, US      169.43 ms
11  218.30.48.142    AS4134  [CHINANET-US]    Los Angeles, US      164.30 ms
13  179.255.100.100  AS906                    Los Angeles, US      170.27 ms

Each line is one hop: its number, IP address, network number (ASN), network name in brackets, location and round-trip time. The full output also shows the network’s owner and three time samples per hop. A * hop didn’t reply.

Read this one from top to bottom. The trace leaves Guangzhou on China Telecom’s provincial network, touches the 163 backbone once (202.97.43.78), then rides CN2 (59.43.x.x) across the Pacific. The time jumps from about 8 ms to 169 ms at hop 10, which is the ocean crossing.

The CN2 hops show * instead of a network number. That’s because 59.43.0.0/16 isn’t announced in the global routing table, according to Hurricane Electric’s BGP Toolkit. APNIC registers the range as “CN2-BB”, and NextTrace labels it CN2-BackBone.

These names appeared in our traces. The network numbers are from APNIC’s registry and PeeringDB:

Name in NextTrace	Network	Network number
CN2-BackBone, CN2-Global (59.43.x.x)	China Telecom CN2	AS4809
CHINANET-BB	China Telecom’s 163 backbone	AS4134
CU169-BACKBONE	China Unicom’s standard backbone	AS4837
CNC-BACKBONE	China Unicom CUII, known as 9929	AS9929
CUG-BACKBONE	China Unicom Global	AS10099
CMNET	China Mobile inside China	AS9808
CMI-INT	China Mobile International	AS58453
CMIN2-NET	China Mobile’s premium CMIN2	AS58807

Only part of 202.97.x.x is the 163 backbone. APNIC registers 202.97.0.0 to 202.97.95.255 as “CHINANET-BB”; the upper half belongs to other networks. The CN2 GIA guide explains the networks in detail.

Trace from your server to China

On the server you want to check, run:

nexttrace -F

The -F option is NextTrace’s “One-Key Fast Trace to China ISPs”. Its source code lists the targets: endpoints in Beijing, Shanghai and Guangzhou for China Telecom 163 and CN2, China Unicom 4837 and 9929, China Mobile and CMIN2, and China’s education network. NextTrace’s README adds Hangzhou. The endpoints are hostnames such as ipv4.sha-4134.endpoint.nxtrace.org, China Telecom 163 in Shanghai.

This shows the route from your server into China, which Chinese hosting guides call the return route. It’s the direction that carries downloads to users in China. If ICMP is filtered, add -T to use TCP.

Trace from inside China

A traceroute only shows the forward path, as Richard Steenbergen explained at NANOG 47. The route from China to your server can be different. NextTrace’s --from option runs the trace through Globalping, “a global network of probes to run network tests like ping, traceroute and DNS resolve”, run by jsDelivr.

nexttrace --from "AS4134" 203.0.113.10

Replace 203.0.113.10 with your server’s IP. The location can be a country, city, network number or provider. AS4134 picks a probe on China Telecom, AS4837 on China Unicom and AS9808 on China Mobile. Anonymous users can run 250 tests an hour.

On October 12, 2026, Globalping’s probe list had 77 probes in mainland China:

• The largest groups are in Tencent Cloud and Alibaba Cloud data centers.
• A few run on carrier networks: China Telecom in Guangzhou, China Unicom in Wuhan, Changsha and Shanghai (one on 9929), and China Mobile in Nanning, Wuhan, Zhengzhou and Beijing.

Routes from data centers can differ from home broadband, so prefer the carrier probes.

Globalping says it “relies on the community to expand its probe network”, and sponsors can install hardware probes in their home or office. Use the probes to check your own servers. Don’t send them to blocked services, which could put the people hosting them at risk.

What our traces showed

We ran these traceroutes through Globalping on October 12, 2026, at about 8 am China time, which is off-peak. The targets were two DMIT looking-glass servers in Los Angeles: lax-pro.lg.dmit.sh on DMIT’s Pro line, which DMIT says uses China Telecom CN2 GIA, and lax-t1.lg.dmit.sh on its T1 line. Both addresses are on DMIT’s own network, AS906. The T1 server didn’t reply to the probes from China, so its times are to the last hop that did, in Los Angeles: DMIT’s router for China Telecom and China Mobile, GTT for China Unicom.

Probe in China	To the Pro server	To the T1 server
China Telecom, Guangzhou	One 163 hop, then CN2 (59.43.x.x) to Los Angeles. 170 ms	163 backbone to San Jose, then GTT. 165 ms
China Unicom, Changsha	4837, then 9929, then China Unicom Global to Los Angeles. 162 ms	4837 to Los Angeles, then GTT. 191 ms
China Mobile	CMIN2 to Los Angeles (Beijing probe). 155 ms	China Mobile International via Miami and Dallas (Nanning probe). 231 ms

The other direction, from probes on three hosting networks in Los Angeles to NextTrace’s Shanghai endpoints:

Probe in Los Angeles	To China Telecom	To China Unicom	To China Mobile
DMIT (AS906)	China Unicom Global and 9929, then the 163 backbone in Shanghai. 128 ms	China Unicom Global, then 9929. 124 ms	CMIN2. 129 ms
IT7 Networks (AS25820, BandwagonHost’s network)	CN2 into Shanghai. 126 ms	4837 via San Jose. 181 ms	Hurricane Electric, then China Mobile International. 193 ms
Vultr (AS20473)	GTT, then the 163 backbone. 135 ms	GTT, then 4837. 245 ms	China Mobile International. 140 ms

What to take from it:

• The China Telecom trace to the Pro server matched the textbook CN2 GIA pattern: one 202.97 hop, then 59.43 hops across the Pacific. The trace to the T1 server crossed on the 163 backbone instead (202.97.58.254 in San Jose).
• The premium routes were often faster even off-peak. Vultr’s route to China Unicom took 245 ms against DMIT’s 124 ms, and China Mobile’s route to the T1 server took 231 ms against 155 ms to the Pro server. Others were close: Vultr reached China Mobile in 140 ms.
• Telecom latency was close on both routes off-peak. The difference CN2 GIA makes shows up in congestion at busy times, as the studies in the CN2 GIA guide found.
• The DMIT probe didn’t use CN2 to reach China Telecom; it went through China Unicom’s premium network first.

These are single runs. Globalping doesn’t say which plan the DMIT and IT7 probes are on, and the two China Mobile traces came from different probes, so don’t read them as a verdict on either host. The raw output is kept with our records.

Options worth knowing

Option	What it does
-T / -U	Trace with TCP SYN (port 80) or UDP instead of ICMP
-P	Print the path by network and location
-t, -r	MTR mode: keep probing each hop, or print a report
-j, --table	JSON output, or a summary table
-c	Classic output “like BestTrace”
-g en	English labels (the default is Chinese)
-n	Skip reverse DNS lookups
-M	Don’t create the trace map
-d	Choose the location data provider, or disable-geoip

Privacy

By default, NextTrace sends each hop’s IP address to its own location service, at api.nxtrace.org. On our runs it picked a server it labeled “DMIT.NRT”. Its version banner lists DMIT.io, Misaka.io and Saltyfish.io as sponsors.

It also prints a link to a trace map on nxtrace.org after each trace. Add -M to turn the map off and -d disable-geoip to skip the lookups. Setting NEXTTRACE_ENABLEHIDDENDSTIP=1 hides the destination in the output, which helps before you share a trace.

NextTrace and BestTrace

BestTrace is IPIP.net’s visual traceroute. Its App Store listing was last updated in August 2025, and IPIP.net’s site didn’t load when we checked on October 12, 2026. NextTrace covers the same job, and -c prints its output in BestTrace’s classic layout.